Taco circulator pump repair


  #1  
Old 10-04-15, 12:17 PM
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Taco circulator pump repair

Woke up this a.m. to hearing a clicking coming from my R7284U controller. On a call for heat, the burner was not getting a spark. The R7284U was just cycling trying to initiate spark.

The Taco circulator pump was also leaking.

I turned off the boiler for about an hour and then came back to investigate. Upon turning on the boiler switch and calling for heat at the thermostat, the system came to life and worked just fine. So what happened?

The top of the aquastat was wet; ditto a few droplets on the R7284. I believe water from the circulator pump leak got onto the aquastat wires and caused them to not send the proper signal to the controller on the call for heat.

So now on to fixing the Taco circulator, Model 007-F5.

The pump is working just fine, and no whine from the motor. I first tried tightening up the 4 bolts that connect the motor to the circulator casing body; that did nothing. I then took apart an old Taco (same model) and found the metal gasket that sits between the motor and the pump casing, and the replaceable cartridge. Under the cartridge, there is a small rubber gasket for the casing that the impeller sends the water through.

Given the pump is working fine with no noise, I believe it is this rubber gasket that has worn out.

Taco calls it an o-ring. The Taco part # for the casing o-ring is 008-005RP. My local hardware store had a 2 3/16" ID x 2 3/8" OD o-ring that fitted perfectly in the old casing. However, it does sit a slightly higher in there.

Questions:

1. Given my symptoms, does my diagnosis seem correct?

2. This is not a Taco 008-005RP o-ring. Any reason it will not work for me when I bolt it all back together, given it is slightly high?

3. Other than just remove the old gasket, aka o-ring, and clean off any remnants of the o-ring, is there anything else I need to do there, e.g. a little bit of lubricant (of some type??) on the o-ring?

4. The Taco circulator pump directions say to drop the system pressure to 0 PSI, etc. But I have a gate valve on both ends of the pump. Yes, I with I had used ball valves 20 years ago. Oh well! Any reason I can not turn the system off to let it cool a bit, close these 2 valves, catch the little water between them with a towel and avoid dropping the system pressure to 0 first?

I plan on doing this work tomorrow morning. For now a rag that drips into a bucket is keeping the water from getting on the boiler components; and I covered up the aquastat and controller each with a plastic container.

While at it, I'll also change put the 2 flange gaskets on either end of the circulator pump.

Thanks for the quick reply.
 
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Old 10-04-15, 12:36 PM
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Isolation valves on either side of the pump are ideal but seldom actually seen in most installations. Taco tells you to empty the system as they have no idea if you have isolation valves.

I like to use a little bit of silicone grease on o rings.
 
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Old 10-05-15, 04:22 AM
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Thanks for the quick reply.

It is the little things that can mess up the easy jobs, so 2 followup questions just to be sure:

The Taco is mounted vertically on the system. It is easy enough to just leave the unit in place, unbolt the motor portion, pull it off and change the o-ring. Is this okay, or might it easily lead to getting water in the motor portion?

Also, how tight should the bolts be when retightened? They were surprisingly easy to unbolt on the old unit I had.
 
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Old 10-05-15, 05:46 AM
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I can't answer the question of whether or not a thicker O-ring will cause a problem but because it might I would be reticent about trying it. The bolts do not need to be "gorilla tight" but definitely wrench tight.

Certainly no reason to drain the system if the isolation valves hold tight. Many reasons to NOT drain the system.

You MAY have a problem with the ignition transformer or ignitor starting to fail or it could be as simple as the ignitor electrodes need to be cleaned, pointed and adjusted.
 
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Old 10-05-15, 03:08 PM
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Leak resolved – now WHAT is that noise?

You MAY have a problem with the ignition transformer or ignitor starting to fail or it could be as simple as the ignitor electrodes need to be cleaned, pointed and adjusted.
Not sure what prompted this comment. However, the boiler was just cleaned a few days ago, the Carlin transformer is 1 year old and functioning properly, the electrodes were replaced and adjusted to spec.

Back to the Taco circulation pump.

I talked with Taco tech support this a.m. to see if it was an issue using the o-ring I picked up at the local hardware store. Taco stated that their o-ring is made to fit. I noted mine also fit; the feedback was paraphrasing “well if you want to use it, go ahead, but then it's not our (Taco) problem if it doesn't work.”

So I spent 2 hours trying to source their casing o-ring (part # 008-005RP). Two local plumbing supply stores (F. W. Webb and Peabody) did not have it in stock. The special order cost was ~$15 plus ~$13 for shipping. $28 for an o-ring? I then called Emerson and Swan, the distributor for Taco; they were not able to identify any place that sold it.

I did find out that the Taco o-ring is made by Minnesota Rubber Company. It is 103” thick, 2.175” in length (I did not translate my 2 3/16” ID x 2 3/8” OD into a circumference length), and is rated for 1.015 PSI tensile strength. Other than the one I bought fitting, I have no idea how well it matches with these spec numbers. But I include it here because possibly it is relevant.

The installation went smoothly. Post installation, I purged the 2 zones and turned the boiler on. No leaks from the pump – good! And the pump sounded good; its normal hum when it is running.

But then I started to get a rattle or chatter from the pump area. I could still hear the hum of the pump under the chatter, but am perplexed as to what it is. This chatter typically will go away if 1) the pump stops cycling water through the zone, or 2) the boiler burner comes back on.

However, once the burner goes off, the pump will sound fine for the first 2 – 2.5 minutes and then start to rattle or chatter again. Once the chatter starts, it continues until, as noted, either the burner goes back on, or the system naturally stops circulation water. And so on.

I called Taco; the tech had no idea what it might be. He could hear it with my cell held by the pump area. His only thought was possibly some debris in there, or air. Debris is unlikely; I cleaned off the casing where the new o-ring went; ditto for the area around the impeller. Plus any debris would be from the old rubber o-ring that was mostly disintegrated.

The air pocket theory is more plausible since initially there is no chatter, then it starts up. But this would imply the air pocket moved through the zone, got to the pump, and somehow each time got trapped there. And when I call for heat and listen to the pipes on the downstairs, I do not hear any air pocket going through the pipes.

Possibly something to do with the o-ring I used? Possibly the motor starting to go, but then why is it ok after the burner runs for 2 – 2.5 minutes and then chatters? Possibly ???

I'm at a loss as to what it is, and how to get rid of it.

Anyone?

Thanks.
 
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Old 10-05-15, 03:15 PM
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Woke up this a.m. to hearing a clicking coming from my R7284U controller. On a call for heat, the burner was not getting a spark. The R7284U was just cycling trying to initiate spark.
That is what prompted Furds reply.... from your first post.

You're basically on your own when you rebuild a circulator pump. I've always just replaced them.

I have noticed them rattle when they get air in the impeller. I don't think your o ring has anything to do with the problem.
 
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Old 10-05-15, 03:16 PM
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You MAY have a problem with the ignition transformer or ignitor starting to fail or it could be as simple as the ignitor electrodes need to be cleaned, pointed and adjusted.

Not sure what prompted this comment.

Maybe THIS?


Woke up this a.m. to hearing a clicking coming from my R7284U controller. On a call for heat, the burner was not getting a spark. The R7284U was just cycling trying to initiate spark.

A bad pump isn't going to prevent the boiler from firing... unless of course you think that the water dripping on the controls was the cause, in which case I hope there isn't any latent damage ... they may be working NOW, but what about in a month or two? That's the way it goes sometimes when stuff gets wet.
 
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Old 10-05-15, 03:21 PM
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I started to get a rattle or chatter from the pump area
Cavitation sounds like marbles rattling around inside the pump. Does it sound like that?

Are you sure you opened all the valves you might have closed?
 
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Old 10-05-15, 04:06 PM
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Is the pump mounted so the motor is horizontal? Taco does not recommend the motor to be vertical unless the water pressure exceeds some figure that I have forgotten. Having the motor vertical and on the upper side will allow air to collect in the motor casing. When the burner is firing the pressure might rise enough to compress the air bubbles and allow proper water flow through the pump motor casing.

And yes, it was your original comment about the burner not igniting that prompted my remarks about the transformer and spark points.
 
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Old 10-05-15, 06:27 PM
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The Taco is mounted vertically on the system.
Following Furd's last post, yes, we need to know what you mean by this.

There is only one instance that Taco allows a pump mounting with the motor shaft NOT horizontal.

Name:  mounting position.jpg
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So are you saying that the motor shaft is vertical?
 
  #11  
Old 10-05-15, 07:26 PM
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Cavitation sounds like marbles rattling around inside the pump. Does it sound like that? Are you sure you opened all the valves you might have closed?
Marbles - yes, probably. Opened valves - yes, all were opened.

Is the pump mounted so the motor is horizontal?
Yes, the motor/motor shaft is horizontal. Sorry for the confusion when I said it was mounted veritcally. It sits on the vertical supply pipe from the boiler, but the motor/motor shaft is horizontal, as per the standard position in the picture of the 3 positions.

it was your original comment about the burner not igniting that prompted my remarks about the transformer and spark points.
Ah, yes, the behavior I saw did not return. I kept a a plastic container over the aquastat and controller until I installed the new o-ring today. Hopefully, the pump leak did not do any lasting damage as per NJT's comment.

Now where to go from here?
 

Last edited by jdbs3; 10-05-15 at 07:45 PM.
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Old 10-06-15, 05:51 PM
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Update - still looking for input on how best to proceed

Cavitation sounds like marbles rattling around inside the pump. Does it sound like that?
Yes, marbles good describe it. I spent some time today reading up on cavitation. Found some interesting web sites; see:

Diagnosing Hydronic Heating System Noise

http://websupport.completewatersyste...g-System-Noise

and

Is this pump cavitation or something else?
Am I experiencing pump cavitation or something else? | PumpScout

With limited time today, I decided to see if additional purging would help. I did get a little more air out of the 2 zones for the main floor and second floor. This changed the symptom. Now I get what sounds like a babbling brook (but not real loud), and it is not until 6-7 minutes that I get the rattling or marbles sound. So it looks like there was some air in the system, albeit not much.

I then decided to also purge the boiler itself. Up to now, I had isolated it by closing 2 gate valves on the inlet and outlet side. I left these valves open, and hooked a hose to the drain by the floor, and then purged the whole system by opening up, one at a time, each of the 2 zones. I got an initial spirt of air, but that was all. It also did not make any additional improvement on the babbling brook and marbles sounds. Arg!

What I have not done is purged the water heater zone; I've never purged this before. I also have a zone in the basement that is never used. I had removed the zone valve head years ago, but never bought a new head since we never use the basement.

Questions:

1. Does it seem like I am on the right track? Or are there other suggestions?

2. Does it matter when I am purging how fast I let the water circulate? Today, I was opening the drain about a 1/4 turn, then increased it to a 1/2 turn. If the flow is too fast, might the water "ride over" an air pocket?

3. Is there a need to purge the water tank zone in the same way, by opening up the zone valve?

4. Does it matter if I skip the basement zone that I have not used in 25 years and has never had an impact on purging before?

The irony is that I replaced a number of components this summer (expansion tank, back flow preventer, pressure regulator, etc.) and the purging was fast and uneventful. Now I open up about an inch of pipe and have all kinds of problems.

If more purging does not work, then I will remove the cartridge to see if i have any partlcle of debris on it.

If all else fails, I have a new pump.

All feedback appreciated.

Thanks
 
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Old 10-06-15, 06:13 PM
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If more purging does not work, then I will remove the cartridge to see if i have any partlcle of debris on it.
Check for damage to the impeller - it can be caused by cavitation.

I wouldn't rush into installing a new pump. Cavitation, if that is the problem, isn't caused by the pump itself as much as the suction piping into the pump. If the suction piping is clogged or not properly arranged, or the expansion tank isn't keeping the pressure up at the pump, or the system pressure is too low, the pressure at the pump's suction can drop below the vapor pressure of the water - causing vaporization and then explosive collapse of the bubbles - like marbles.

What is the system pressure according to the boiler gauge?
 
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Old 10-06-15, 06:44 PM
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Just for the heckuvit, can you post some pictures of the system? I'm not saying it will help, but maybe we'll see something...
 
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Old 10-07-15, 05:14 AM
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What is the system pressure according to the boiler gauge?
The system pressure is 16 - 18 PSI. Fairly constant given we are now into the beginning of the heating system.

Picture of system attached. Since this picture was taken, I installed a new expansion tank, back flow protector/pressure reducer, pressure relief valve, and new air vents, all about 6 months ago.

the pressure at the pump's suction can drop below the vapor pressure of the water - causing vaporization
Given the only thing that has changed is my 5 minutes of opening up the circulator pump, cleaning off the old o-ring smuge around the impeller, and where the o-ring sits in the casing, and installing a new o-ring, why would this now suddenly happen?

If all else fails, then I have the new pump.

1. BUT, if I can't solve this problem, then won't I encounter the same problem with the new pump???

I feel I should start by assuring I have 0 air left in the system. I'd appreciate feedback on my purging questions from 2 days ago. Possibly I am not being aggressive enough in the purging.

2. Does it matter when I am purging how fast I let the water circulate? Today, I was opening the drain about a 1/4 turn, then increased it to a 1/2 turn. If the flow is too fast, might the water "ride over" an air pocket?

3. Is there a need to purge the water tank zone in the same way, by opening up the zone valve?

4. Does it matter if I skip the basement zone that I have not used in 25 years and has never had an impact on purging before?

Check for damage to the impeller
5. And if the impeller has been damaged, should I then switch to the new pump, or use the old pump until it just does not work?
 
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Old 10-09-15, 11:54 AM
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Update – progress, but …

Finally got back to the boiler today. Googled everything I could find on boiler noises, cavitation, and purging tips.

In the past when I purge, I had not increased the boiler pressure using the PRV rapid fill lever. This was due to 2 bad experiences where when this lever was used, the 1156F PRV subsequently leaked. And yet when not using the lever, the purging always worked.

But after talking with a Watts tech who noted that if the water flow entering the system is less than the drain flow out, then I am just introducing more air into the system. Given the 1156F was just recently installed, I decided to use the rapid fill lever.

I increased the flow from the drain valve and kept the lever up. Took about 20 gallons of water out while purging the first and second floor zones. And yes, got a little bit more air. I continued to purge both zones for an extra couple of buckets to assure no more air in the system, and no noise of air in the return pipe.

I did not purge the hot water boiler zone; for some reason the lever would not pull down, and I did not want to force it. Most likely due to the awkward position of this zone valve. I also skipped the basement zone which is never used.

Turned the boiler back on and initially it appeared that I had eliminated the marbles/rattling sound. There was a very slight 'running brook' like sound, but you could only here this standing right next to the pump. This pump noise stayed constant through the next boiler burn cycle (call it 6 minutes before burn + 5 minutes burn), and continued after the burner went off. But then 6 - 7 minutes after, the marbles/rattling sound came back. Arg!

And yet, the marbles/rattle sound goes away when the burner comes back on, and stays off for another 6 – 7 minutes.

Oh, I also tightened up the 4 bolts holding the motor to the pump casing in case some air was leaking in that way.

So now I'm more than frustrated. Sunday I'll remove the motor and check for pitting damage or debris on the impeller, and try it again. If this does not work, then I'll install the new pump.

While I did not get any reply to my last questions, I would appreciate feedback on each of the following.

1. The only thing that is different is that I used an o-ring form the local hardware store. Might this not be creating a good seal or ? even though the pump is no longer leaking? Possibly the only o-ring that works is the Taco $28 one.

2. What explains why the marbles/rattling sound goes away each time the burner comes on, and for 6 – 7 minutes after it goes off? The boiler pressure does not change during this time.

3. I've always purged when the boiler service switch is off. Can I purge when a zone is calling for heat and the boiler is cycling? If so, would it be better to use the boiler drain on the return pipe just above the boiler, or the drain at the base of the boiler, or does it not matter?

4. Before each purge, I closed the gate valves to the boiler on the supply and return sides. I'd also like to purge the boiler piping, but do not want to introduce cold water into the boiler that could possibly crack the cast iron 'pipes' in the boiler. Should I try to purge the boiler itself, and if so how? Possibly by purging when the whole system is running?

Signed,
Determined to resolve this issue.
 
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Old 10-09-15, 03:06 PM
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Try to do a little better with the pics please... and a couple more from different angles and a little further back. Let's see the whole thing.

if the water flow entering the system is less than the drain flow out
How would this even be possible? Is he thinking that air will pass the exiting water and enter the system?

The system pressure is 16 - 18 PSI.
With what gauge?

Read this:

http://www.doityourself.com/forum/bo...ure-gauge.html

Your expansion tank is pretty old... when was the last time it was properly recharged?

Read this:

http://www.doityourself.com/forum/bo...sion-tank.html

It appears that you've got GATE VALVES above and below the pump. How certain are you that they are opening again after you've closed them? Gate valves have a nasty habit of the gate getting wedged into the slots and when the valve is opened again the 'knob' that turns in the gate to pull it up actually breaks out of the gate. The gate stays where it is and the knob feels like the valve is opening.
 
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Old 10-09-15, 03:09 PM
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If the flow is too fast, might the water "ride over" an air pocket?
No, that won't happen.

If you purge to SLOW, the air won't move. THAT's when the water will 'ride over' the air. You need a flow velocity in the piping of at least 2 Feet per Second to move the air. Slower flow will move air along a HORIZONTAL pipe, but will not move it DOWN a VERTICAL pipe.
 
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Old 10-09-15, 03:13 PM
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While I did not get any reply to my last questions
Because it takes a lot of time to answer that many questions all at once. Better to space them out even though it may take more time to get all the answers.

Please understand that we're all volunteers here and answer when we have time to do so. Just FYI.
.
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When you are purging, you are CLOSING the valve above the pump, correct?
[edit]no need to answer, you did later in the messages]
.
.
Is there a need to purge the water tank zone in the same way
If it's a short enough run of pipe, probably not.

There could be a significant amount of air in the basement zone though... there's a zone valve on one end of that zone, but is there an isolation valve on the other as well?
 

Last edited by NJT; 10-09-15 at 03:43 PM.
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Old 10-09-15, 03:19 PM
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Might this not be creating a good seal or ? even though the pump is no longer leaking? Possibly the only o-ring that works is the Taco $28 one.
I highly doubt the O-ring is an issue.

What explains why the marbles/rattling sound goes away each time the burner comes on, and for 6 – 7 minutes after it goes off? The boiler pressure does not change during this time.
Don't have an answer for that one yet...

BUT, I would expect SOME change in the pressure if the water is cooling and circulating for 6-7 minutes after the burner kicks off. All the more reason to suspect that gauge.

When the boiler is COLD, what pressure do you see?

When the boiler is HOT, what pressure do you see?

LOW pressure can cause issues with a pump cavitating.

Here's a theory:

Cold water is DENSER than hot water, thus even if the gauge is lying to you and the pressure is LOW, it may not cavitate.

When the water is HEATED and the density decreases, at the same time because the pressure SHOULD BE increasing, the extra pressure may be overcoming the lower density.

After the burner kicks off and the water starts to cool, the pressure decreases below the 'NPSH' (Net Pressure Suction Head) required to prevent the pump from cavitating.

Just a possible theory...
 
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Old 10-09-15, 03:28 PM
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I've always purged when the boiler service switch is off. Can I purge when a zone is calling for heat and the boiler is cycling? If so, would it be better to use the boiler drain on the return pipe just above the boiler, or the drain at the base of the boiler, or does it not matter?
Please explain the purge process that you use. Tell us what valves you manipulate, where you connect your hose, etc.

And please add some more pics so we can see all the valves you talk about.

In general, only purge when the boiler is BELOW 100F. To not do so risks cracking the boiler by sending cold water through a hot boiler.

It's always best to use the drain directly on the return because once the air comes down into the boiler, it's not going to continue on down to the drain, it's going to float up to the top, only to be recirculated again. It's all about that 2 FPM flow rate. Once that water gets back into the boiler it SLOWS DOWN because of the larger area and the drop in pressure, and then just meanders up to the top of the boiler.
 
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Old 10-09-15, 03:32 PM
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4. Before each purge, I closed the gate valves to the boiler on the supply and return sides. I'd also like to purge the boiler piping, but do not want to introduce cold water into the boiler that could possibly crack the cast iron 'pipes' in the boiler. Should I try to purge the boiler itself, and if so how? Possibly by purging when the whole system is running?
OK, I see that I made some premature statements. You are already aware of the hazard of cracking the boiler.

Chances are that you won't need to purge the boiler itself...

But, it brings up another question:

On the top of your air scoop, there's an AUTOMATIC AIR VENT.

Is that vent functional? I see some rust streaks running down the air scoop indicating that it WAS leaking, and might STILL BE.

Is the cap on the top of that vent LOOSE to allow air to escape?

If it's not, the air scoop is doing no good at all.

If you loosen that cap and water leaks out, it needs replaced.

If it's all clogged up with minerals, it needs replaced.



.
.
.
OK... is that all your questions?
 
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Old 10-09-15, 03:50 PM
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So, bottom line time:

You need to KNOW what the pressure REALLY IS in the boiler.

It's a really good idea to verify that your expansion tank bladder is intact and that the tank is holding the proper air charge before continuing.

Make sure that those gate valves have not wedged themselves shut (even partially). A closed valve on the suction side of a pump is a sure way to make it cavitate.

Google this: "gate valve won't open" to see just how often it happens!
 
  #24  
Old 10-09-15, 04:40 PM
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In addition to all NJT mentions, is that air vent on the top of the boiler,near the water outlet, working properly? That particular boiler may have an internal pipe that allows air to leave the water inside the boiler, collecting at the top, above the outlet. If I am correct about this, AND the vent is not working, you may have a considerable amount of air in the boiler that is acting as an expansion tank. This would explain the minimal pressure excursions from cold to hot and back. Along with an incorrectly reading pressure gauge you could be running way low on system pressure.
 
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Old 10-10-15, 06:13 PM
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NJT, Furd,

All good feedback - thanks. It will take me a few reads to digest all of it and follow up with you, including some better pics. What follows is just initial feedback.

When you are purging, you are CLOSING the valve above the pump, correct?
NO. I have been closing the valve below the pump. Arg!

1. Might this explain why I am having all these problems???????? If so, please explain.

Other initial feedback:

Your expansion tank is pretty old... when was the last time it was properly recharged?
The expansion tank is new; was just installed ~May, 2015.

The air vent above the air scope is about a year old and the cap is loose; the rust on the air scope is from the prior air vent that did leak. All other air vents were replaced ~May, 2015.

The pressure gauge usually reads 20 PSI when the system is not running, it then drops to ~15 PSI when the boiler runs. This is ~2 PSI less than the 16-18 I quoted before, and is a change since I did the purging. I had felt the pressure was too high after the purge, so drew off a bit of water to drop the pressure.

Once the thermostate calls for heat and the pressure drops from 20 PSI, I do not see any change in pressure as the system goes from just circulating hot water, to burner on, to burner off, to continuing to recirculate hot water.

In general, only purge when the boiler is BELOW 100F. To not do so risks cracking the boiler by sending cold water through a hot boiler.
Thanks, this is what I need to know.

With all my purges, the boiler was warmer than 100 degrees. However, with the exception of only one, I had isolated the boiler itself with the gate valves. I did briefly purge the boiler itself once, but stopped it after a very short time, due to my concern about cracking the pipes there. That led to my question on this.



What I need to do, as per the feedback:

- Know what the pressure really is. As I recall, when I upgraded many of the parts back in may, I looked for a new pressure gauge, but could not source one locally that had the same type of stem mine had. I now need to look harder for one.

- Make sure that those gate valves have not wedged themselves shut (even partially). That could be the real problem. I'm not sure how to do this, but will start by googling it.

- Read up on 'gate valve won't open'. That's a new one for me. Possibly this will tell me how to verify whether the gate valves are wedged.

- Verify that your expansion tank bladder is intact and that the tank is holding the proper air charge before continuing.

- Summary of how I purge.

- More pics.

- Possibly other things; I'll reread the feedback.

I've got some home work to do before providing more feedback.

2. One other question right now. At one point when I was purging one of the zones with the boiler isolated from the purge, I ended up getting a bucket filled with black water; it then ran clear again. The only thing different was that I had increased the pressure some using the PRV rapid fill level. I was actually trying to keep the water flow at 3.2 gpm for a 3/4' pipe based on a Taco document that stated (see quote below). This is actually fairly fast to fill a bucket with 3.2 gallons of water in a minute. I was concerned that the PRV set at ~15 would not refill the system at this flow rate, so I used the rapid fill lever.

[Taco] Flow velocities of at least two feet per second (2 fps) are required to efficiently entrain air bubbles and bring them to the drain valve.
This is also as per NJT's comment.

Make sure that those gate valves have not wedged themselves shut (even partially). A closed valve on the suction side of a pump is a sure way to make it cavitate.
3. I believe the suction side of the pump is at the top of the vertical pipe closest to the expansion tank - correct? Also, a quick google search did not tell me how to tell if the gate valve is wedged. Is there an easy way?

Please understand that we're all volunteers here and answer when we have time to do so. Just FYI.
Apologies, noted and much appreciated. I usually try to ask all the questions I can think of at once hoping to cut down on the dialogue.

Thanks again!
 

Last edited by jdbs3; 10-10-15 at 07:13 PM.
  #26  
Old 10-11-15, 10:24 AM
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NO. I have been closing the valve below the pump. Arg!
That's actually OK, either one will do the same job. The point is that you need the 'roadblock' there before the boiler in order for the water to go through the zones... not a problem.

The pressure gauge usually reads 20 PSI when the system is not running, it then drops to ~15 PSI when the boiler runs.
The reason the gauge DROPS when boiler runs is because the pumps differential pressure is being subtracted from the static pressure in the system.

Your pump is pumping TOWARD your expansion tank, if it were pumping AWAY from that tank, you would not see the pressure change in the boiler when the pump runs... except for an INCREASE as the water was heated.

No big deal really, but if you ever get the boiler replaced, or do any re-piping on that one, swap the position of the pump and the air scoop / expansion tank.

By the way, if you were pumping AWAY from the tank and air scoop, I guarantee you would never even NEED to purge!

Once the thermostate calls for heat and the pressure drops from 20 PSI, I do not see any change in pressure as the system goes from just circulating hot water, to burner on, to burner off, to continuing to recirculate hot water.
Yeah, you might want to verify that gauge...

could not source one locally that had the same type of stem mine had. I now need to look harder for one.
Or build up the adapter as outlined in the pressure gauge thread I linked to.

All new boiler gauges are crap. It will stop working properly in a couple years, if not sooner... even right out of the box. Use a quality gauge on a drain and you're good to go.

I was actually trying to keep the water flow at 3.2 gpm for a 3/4' pipe based on a Taco document that stated (see quote below). This is actually fairly fast to fill a bucket with 3.2 gallons of water in a minute. I was concerned that the PRV set at ~15 would not refill the system at this flow rate, so I used the rapid fill lever.
You could actually go up a bit past 4 GPM for 3/4" pipe... but that's for 'normal' operation, you can exceed that occasionally when purging.

Using the fast fill for purging is exactly one of the reasons that it's there!

3. I believe the suction side of the pump is at the top of the vertical pipe closest to the expansion tank - correct? Also, a quick google search did not tell me how to tell if the gate valve is wedged. Is there an easy way?
I hope not! If it is, then you're pumping through the boiler bass ackwards! and that's not a good thing.

The pump is on the pipe coming from the TOP of the boiler right? (at least that I can see in the pic) That is the HOT SUPPLY OUT of the boiler to the system. Your pump should be flowing UP, there should be an arrow on the casting. Please check that and let us know.

On second thought, you don't have to check. The fact that the boiler pressure gauge DROPS when the pump is running is evidence enough, but please confirm.
 
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Old 10-11-15, 12:04 PM
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The pump is on the pipe coming from the TOP of the boiler right? ... pump should be flowing UP, there should be an arrow on the casting.
Yes, and yes, the arrow is facing up. So the suction side is on the bottom of the mounted pump; now I know.

The pipe prior to the zone valve split is 1" OD. Past the zone valves it is 3/4" throughout the 2 zones, and returns to a 1" pipe on the veritcal return pipe. So I am basing my flow rate on the 3/4" zone runs.

could actually go up a bit past 4 GPM for 3/4" pipe
Wow, that is fast. Yes, I would need to use the fast fill to keep up with 4 gallons/minute; I don't expect the PRV set at default of 12-15 PSI could keep up with the 4 gpm with using it.

But why did I get one bucket filled with black water?

And is there an easy way to tell if my gate valve is wedged?

I'm off to Home Depot to look at ball valve replacements. Later today or tomorrow, I'll add some pictures, explain how I purged to date, and summarize my plan for going forward.

Have a good holday weekend.
 
  #28  
Old 10-12-15, 06:37 AM
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But why did I get one bucket filled with black water?
The black water is 'magnetite' in the water. It's another form of Iron Oxide (rust). Also known as Lodestone when found in nature. It's nothing to be concerned with... normal.

Smelly black water is normal in boiler systems and is NOT a reason to 'flush' the system as many people believe. You WANT that smelly old water in the system because every time you flush with fresh water, you are also adding OXYGEN.

For corrosion (rust) to occur, you need three things: FERROUS METAL, WATER, OXYGEN

Take away any ONE of that triad and no corrosion will occur.

After water has been circulating in your system and is heated repeatedly, with the proper air removal vents operating, the air (oxygen and other gases) will be driven from the system and the water becomes INERT and won't cause further rusting of the ferrous components.

Bottom line: Never flush or power purge unless it is ABSOLUTELY NECESSARY. Leave that smelly old water alone!

And is there an easy way to tell if my gate valve is wedged?
No, not really.

First and foremost, NEVER let your inner gorilla close a gate valve. NEVER crank it down tight to stop it from dripping. That's what causes the problem.

But let me ask this:

When the system runs, can you 'follow the heat'?

Does hot water make it past the pump?

Does the pump sound change if you close either of the valves (briefly!) while the pump is running?

On some types of gate valves when they break the handle just spins and spins so you know when there's a problem. On others, it will stop, making you think the valve is open when it's not.
 
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Old 10-12-15, 05:03 PM
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Besides everything NJT said about black water, even if you flush it, the replacement water will be black again within a short time, weeks for sure.
 
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Old 10-14-15, 08:36 PM
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Update

When system runs, can you 'follow the heat'? Does hot water make it past pump? Does pump sound change if you close either of valves (briefly!) while pump is running?
Yes, yes, no.

Today, I hooked up a 0 – 30 PSI pressure 'test' gauge to the boiler drain on the return. With no call for heat form a thermostat over the last few days, the burner has run minimally.

The boiler pressure gauge showed 20 PSI, and the test gauge 16 PSI. When I called for heat with the thermostat and the burner went on, the boiler gauge dropped to 15 PSI, and the test gauge to 12.5 PSI.

After that, it was fairly consistent. The boiler gauge goes up to 18 PSI at the boiler temperature increases to 170 degrees, and the test gauge goes up to 15.5 - 16 PSI. When the burner goes off, the boiler gauge will drop to 17 PSI and the test gauge will drop to 15 PSI, at which point the burner goes on and the cycle continues.

When I turned down the thermostat for 1 hour, and then went back to testing it, the test gauge showed 17.5 PSI initially. When the burner went on, the test gauge dropped to 14 PSI. Then as the burner was on, it climbed to 15.5 – 16 PSI.

So fairly consistent wit the test gauge. An initial drop of boiler pressure when the burner first comes on, a pressure increase to 15.5 - 16 PSI as the boiler heats up, a drop to 15 PSI as the boiler temperature drops to 170 degrees, and the cycle continues.

And the rattle/marble noise is still there. Once it starts, it continues to rattle even when the burner comes on. When the burner goes off, there is an initial 1 – 2 minutes with no rattle, followed by the rattle. On the next cycle, when the burner goes off, there is no rattle or it goes away fast, only to return. And the cycle continues.

Arg!

My current plan is to:

- Replace the 3 shut off gate valves with ball valves. After the thread comments on gate valves, I do not want to chance continuing to use them.
- Replace the 1 boiler drain gate valve with a boiler drain ball valve.
- Take the circulator pump off its casing and check the impeller for pitting damage or debris.
- Put it back together and purge the system. I'll send how I have purged in the past after I hear back on this reply.

I've sourced all the parts to replace the gate valves, and am meeting with a person who has helped me with the boiler before to assure I have all the parts needed. Replacing the gate valves would seem easy, but I am constrained by having to assure that what I replace has the same vertical height as what is there now, Additionally, the 'Rube Goldberg' adapters, connectors, nipples surrounding the circulator pump have been there for 20 years. Hopefully, whatever we plan to remove will come apart easily.

So a few questions:

- What are your thoughts now on what is causing the rattle/marbles noise? Pressure too low? If so, how do I increase it slowly to see if it has any effect?

- Any suggestions, or comments, or additions on my plan?

- Any hints on the best way to disconnect some of the 20 year old fittings other then brute force?

Thanks – stay tuned.
 
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  #31  
Old 10-14-15, 10:22 PM
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I want to see a picture of the air scoop and the piping going to the manifold. Also, you didn't answer my question concerning the air vent on the boiler, have you absolutely determined that it in fact purging the air from the top of the boiler? It would be a good idea to install a tee under the vent can and use a manual vent (larger valve) in the side of the tee to ensure that you have removed all the air.
 
  #32  
Old 10-15-15, 04:23 AM
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picture of the air scoop and the piping going to the manifold ... you absolutely determined that it in fact purging the air from the top of the boiler?
See attached picture. Is this what you want to see when you mentioned the boiler manifold? Or?

AUTOMATIC AIR VENT. Is that vent functional? I see some rust streaks running down the air scoop indicating that it WAS leaking, and might STILL BE.

Is the cap on the top of that vent LOOSE to allow air to escape? If it's not, the air scoop is doing no good at all.

If you loosen that cap and water leaks out, it needs replaced. If it's all clogged up with minerals, it needs replaced.
The rust predates the install of the new expansion tank in ~May of this year. No rust or water marks on top of the new expansion tank. The air vent cap is loose, no water is leaking out of it. This one air vent was replaced about 1 year ago.

have you absolutely determined that it in fact purging the air from the top of the boiler?
Other than the above, is there something else I can do to determine this with the system as is?

Thanks.
 
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  #33  
Old 10-15-15, 11:16 PM
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Regarding the air scoop piping I wanted to see if there was room to pipe it properly with a minimum of five pipe diameters (roughly five inches) of straight pipe before and after the scoop and then remount the pump on the outlet of the scoop as it really should be. It appears that to accomplish that would require a major amount of re-piping and this is not the time of year to be doing boiler work.

As for the vent on the top of the boiler...you can remove the tire cap and depress the pin to see if you get a continuous flow of water or spurts of air. As long as you are going to drain the system to install the ball valves in place of the gate valves you might as well add a tee to that vent pipe with a valve to make it easy to manually vent the air from the boiler.
 
  #34  
Old 10-17-15, 11:15 AM
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not the time of year to be doing boiler work.
Agree, but I need to get this cavitation issue resolved.

Still some questions on the boiler pressure and my plans:

1. What are your thoughts now on what is causing the rattle/marbles noise? Pressure too low? If so, how do I increase it slowly to see if it has any effect?

2. Any suggestions, or comments, or additions on my plan?

3. Any hints on the best way to disconnect some of the 20 year old fittings other then brute force?

remove the tire cap and depress the pin to see if you get a continuous flow of water or spurts of air.
Are you referring to the air vent on top of the boiler and next to the vertical pipe the circulator pump is on? I'll do that just prior to when we do the valve replacement.

As long as you are going to drain the system to install the ball valves in place of the gate valves you might as well add a tee to that vent pipe with a valve to make it easy to manually vent the air from the boiler.
Sorry, I do not understand what you are suggesting.

Later today, I'll summarize how I have been purging the system and based on feedback what I'll now do - all for comment.

I'm expecting we will do the valve replacement this next week. Eager to get this done since for now, I am minimizing the use of the heating system to minimize the damage (if any so far) to the impeller. So more later.
 
  #35  
Old 10-17-15, 11:37 AM
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Any hints on the best way to disconnect some of the 20 year old fittings other then brute force?
These are threaded steel joints? Use two 24" pipe wrenches, one on each side of the connection, turning in opposite directions. Otherwise, call a plumber.

If you want to try increasing the system pressure, lift the fast-fill lever on the pressure reducing valve (a.k.a. auto fill valve).
 
  #36  
Old 10-17-15, 01:18 PM
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It appears that I have cavitation, but I am no closer to determining what might be causing it. I feel like I am back to ground zero.

Yes, I will change out the gate valves, check on debris or pitting on the impeller, and re-purge the system.

But I do not have a clue what might be causing the cavitation, nor what to do.

From the feedback so far:

- It might be a partially closed gate valve. If so, then the ball valve replacement will cure this problem.

- Or it might be the system pressure. Based on what I found, might this be the problem?

- Or it might be that the system is not totally purged. But I've purged and purged and purged, and believe I have all the air out of the system.

All of the feedback to date has been great. But I'm unclear on whether there is anything else I could be doing now prior to the ball valve install, or doing at the time I am doing the install to eliminate this problem.

Anyone have additional suggestions?
 
  #37  
Old 10-19-15, 02:07 PM
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Bump and Update

Note: This reply is a bit lengthy. I'm trying to cover everything I need to ask prior to installing the ball valves and checking the circulator pump. Some of my questions may seem simplistic, but I like to understand everything I can beforehand even though I am doing the work with a person who has been doing plumbing for years. I've highlighted questions in red, and would much appreciate a response to each. I've numbered them to make a reply easier, that is avoid a bunch of quotes.

Thank you in advance for reading this and replying.

Purge Process

Please explain the purge process that you use. Tell us what valves you manipulate, where you connect your hose, etc.
A short summary:
- Boiler service switch off
- Boiler temperature at whatever it is. I never waited for it to cool down to < 100 degrees. However, most of the time, it probably was, or close to it. Something to check for in the future.
- Drain hose connected to drain on return line on left side of boiler
- Gate valves on the return and supply side (usually one above pump) closed to isolate boiler
- Pull down lever on zone valve to first floor.
- Drain water, but I always did it at a very slow rate, and never used the PRV fast fill lever. Something to use from here on out to achieve the necessary flow rate.
- Remove about 3 5-gallon containers of water until no more air is coming out of system
- Reset zone valve and repeat for second floor zone valve
- Reset 2nd zone valve
- Open the gate valves
- Skip purging the basement zone which is never used and does not have a zone valve attached currently. 1. Is this okay given it is never used??
- Skip purging the domestic hot water zone
- Skip purging the boiler itself

NOTE: Until now, this has always worked.

you could be running way low on system pressure.
There has been no feedback on the pressure readings with the 0-30 PSI gauge on the return boiler drain. 2. Is my system pressure too low?

Ball Valve Install:

As noted, I am planning (hoping) to get the work done this week. The work will be done with a person who has worked with me before on the boiler; while not a boiler tech, he has both extensive plumbing and electrical experience.

Prior to changing out the gate valves, we will check the pressure in the expansion tank, and the one air vent on top of the boiler. When changing out the gate valves, we will also check the circulator pump impeller.

I will use pipe dope on all connections.

The first gate valve that we will change out is the boiler drain on the right lower side of the boiler. I believe that if we close the 2 gate valves on the return and supply side of the boiler, thus isolating the boiler, then this should cause a vacuum, thus loosing minimal water when we disconnect the gate valve on the boiler drain. 3. Is this correct?

For the existing pump install, there is a combination of copper and black iron fittings. In all cases, the copper and black iron are separated by the brass gate valves. This separation may not be possible with today's fittings that are not always the same length. 4. I've googled copper to black iron connections and there seems to be mixed feedback on it. Is this acceptable given it is a closed system?

5. For a purge of 3.2 - 4 gallons per minute (flow rate of 2'/minute), is the normal PRV pressure of 12-15 sufficient to backfill the water? If not, what pressure is usually needed to maintain this flow rate?

6. When using the fast fill valve, what is the rule-of-thumb for how high to let the boiler pressure rise before pulling down on the lever. The reason I am asking is that the pressure seems to continue to rise even after I've pulled the lever down. I want to avoid getting to close to 30 PSI which would also pop the gauge.


And lastly from my previous reply:,

But I do not have a clue what might be causing the cavitation, nor what to do.*

From the feedback so far:

- It might be a partially closed gate valve. If so, then the ball valve replacement will cure this problem.

- Or it might be the system pressure. 7. Based on what I found, might this be the problem?

- Or it might be that the system is not totally purged. But I've purged and purged and purged, and believe I have all the air out of the system.

And the most important question:

All of the feedback to date has been great. But I'm unclear on whether there is anything else I could be doing now prior to the ball valve install, or doing at the time I am doing the install to eliminate this problem. 8. Anyone have additional suggestions?

Again thanks in advance!
 
  #38  
Old 10-21-15, 04:13 AM
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Bump

Any feedback?

Thanks
 
  #39  
Old 10-26-15, 02:12 PM
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Update with some answers

I'm still on hold waiting for the person who will help me with the boiler modifications and hopefully resolveing the cavitation. In the interim, I've been able to find some of the answers for my questions, though some were like looking for a needle in a haystack. I've included them below for the benefit of others who might have the same questions I had.

Skip purging the basement zone which is never used and does not have a zone valve attached currently. 1. Is this okay given it is never used??

From Taco, since there is no zone valve head on the zone valve, the power head is spring closed. Therefore, there is no reason to purge this system since water is not getting past this power head. Additionally, not doing it has never been a problem before.

There has been no feedback on the pressure readings with the 0-30 PSI gauge on the return boiler drain. 2. Is my system pressure too low?

[From another forum]
the highest pressure the boiler should ever see is stamped on the boiler tag - Usually 30 or 50psi. The pressure the system is designed to operate at is usually 12 - 25 psi for a two story house and 18 - 25psi for a three story.
So my range of 12.5 – 16 PSI is okay.

And from this forum
COLD boiler should be 12-15 PSI. HOT boiler perhaps 8-10 PSI higher.
The first gate valve that we will change out is the boiler drain on the right lower side of the boiler. I believe that if we close the 2 gate valves on the return and supply side of the boiler, thus isolating the boiler, then this should cause a vacuum, thus loosing minimal water when we disconnect the gate valve on the boiler drain. 3. Is this correct?

[From another forum]
To an extent the water will stop, and yes, I can use pipe dope on a fitting that is slightly wet, in this case a nipple for the new ball valve boiler drain.
I HOPE so! I'd prefer not to have to drain the boiler.

4. I've googled copper to black iron connections and there seems to be mixed feedback on it. Is this acceptable given it is a closed system?

Based on another thread I found with input from NJT, Furd and Glimmirie, this is okay. However, with luck, I'll be able to isolate the copper and black iron on either side of the new ball valves. Just hope these fittings come apart easily

5. For a purge of 3.2 - 4 gallons per minute (flow rate of 2'/minute), is the normal PRV pressure of 12-15 sufficient to backfill the water? If not, what pressure is usually needed to maintain this flow rate?
The reason for this question was because from past experience (1156F leaking after using fast fill valve), I'd prefer not to use it if I don't need to.

From a conversation with Watts technical support, I need 0.434 PSI head pressure for every foot of elevation. So with ~16' to the baseboard on the second floor, the default setting of 12 – 15 PSI for the 1156F PRV should be sufficient to overcome gravity and keep up with a flow rate of 3.2 gpm. With this flow rate on my purge, if I am still getting air out after 15 minutes, or if the flow seems to slow down by itself, then I can then use the fast fill lever.

6. When using the fast fill valve, what is the rule-of-thumb for how high to let the boiler pressure rise before pulling down on the lever. The reason I am asking is that the pressure seems to continue to rise even after I've pulled the lever down. I want to avoid getting to close to 30 PSI which would also pop the gauge.

From Watts, there is no rule-of-thum on this. So just pull the lever down well before it gets to high.

- Or it might be the system pressure. 7. Based on what I found, might this be the problem?

Duplicate of # 2,; it is NOT the system pressure.

I've also re-tested with the 0-30 PSI pressure gauge when the rattling/marble noise starts. When the boiler was off for 12 hours in anticipation of the person who will help coming over, the boiler ran for 19 minuts with the water circulating while the temperature in the boiler climbed from 90 degres to 180 degrees. During this time there was no rattle from the circulator pump.

When the burner went off, the pump ran for 2 minutes without any rattle, then it started up again. It seems to go in cycles where it stops when the burner comes on and for shortly after it goes off, to then restarting.

It does not seem to be temperature related. Nor does it seem to be boiler pressure related since the pressure is basically the same just before it starts and just after it stops.

So it might be:

- Wong system pressure. I doubt it since the boiler pressure looks to be ok.
- The old gate valves stuck partially closed. This will be resolved by the new ball valves.
- The expansion tank not pressurized to 12 PSSI. This will be verified when we start the work.
- The impeller not turning. No, since the water is circulating.
- Air in the boiler that is not being evacuated by the 5 month old new air vent. I doube it, but possibly.
- The system is not totally purged. This is possible, but given the purging I did last time with a faster flow rate, I'm doubtful.

So I'm still back to question # 8.

All of the feedback to date has been great. But I'm unclear on whether there is anything else I could be doing now prior to the ball valve install, or doing at the time I am doing the install to eliminate this problem.

8. Anyone have additional suggestions?

and

9. If it is air in the boiler, how do I get it out of there?

Hoping I get a reply to these last 2 questiosn.

Thanks in advance.
 
  #40  
Old 10-26-15, 02:56 PM
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Skip purging the basement zone which is never used and does not have a zone valve attached currently. 1. Is this okay given it is never used??
Not in my opinion. Unless BOTH ends of the loop are closed from the rest of the system with valves that you KNOW are tight the possibility of air being in the loop exists. This can have several ramifications.

So my range of 12.5 – 16 PSI is okay.
12-16 is fine UNLESS your house is more than two stories.

I've googled copper to black iron connections and there seems to be mixed feedback on it. Is this acceptable given it is a closed system?
Yes, lots and lots of systems have mixed metals with no problems even after several decades. The main thing to remember is to NOT flush any more water than absolutely necessary UNLESS you use chemical treatment. I do NOT recommend chemical treatment for most residential systems.

For a purge of 3.2 - 4 gallons per minute (flow rate of 2'/minute), is the normal PRV pressure of 12-15 sufficient to backfill the water? If not, what pressure is usually needed to maintain this flow rate?
The reason for this question was because from past experience (1156F leaking after using fast fill valve), I'd prefer not to use it if I don't need to.
The pressure is all but irrelevant The FLOW necessary will probably not be achievable without using the fast-fill lever. Using the fast-fill lever is no different than allowing the internal spring pressure to open the valve except that you can open the valve farther/wider to allow for the increased flow. Using the fast-fill lever will NOT be a cause of the valve leaking but it MIGHT allow dirt, crap and corruption in the domestic water piping to flow into the Pressure Reducing Valve. This is why you want to not use galvanized piping on the water supply line to the PRV if at all possible and if galvanized IS used you should disconnect the pipe and flush it out to remove any foreign matter.

From a conversation with Watts technical support, I need 0.434 PSI head pressure for every foot of elevation.
Static pressure, when the pump is not running, should be according to the formula PLUS 4 psi. You want this minimum of 4 psi at the highest point in the system. Note that the measurement is from the lowest point of the boiler to the highest point in the system.
 
 

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