Circulator runs constantly when water temp is cold

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Old 11-13-14, 03:49 AM
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Circulator runs constantly when water temp is cold

I have a feeling I'm going to be on this forum for a few weeks. I know there are several problems with my oil fired boiler and hot water system. I'll start with this, the newest of my issues before I make my off-road diesel run...

Upon returning home tonight, I sat down at this computer, 2 yards away from the boiler and heard the sound of water running through it's pipes. I felt the supply pipes heading into the circulator to see how warm they were suspecting we had run out of fuel while I was out. I was surprised to find that the pipes were completely cold. (The house temp had only dropped to 65 by the time I had returned.)

I will be taking detailed pictures and gathering all the information I can on the system for my other issues.. but for now, this quick question...

If there is:
  • a call for heat
  • no fuel left for the boiler to burn
  • nothing but cold water in the entire system
then shouldn't the circulator stop running?

The burner had timed out due to lack of fuel. I can understand the circulator running for a bit if there is still warm water in the system, but isn't there a temperature switch that tells the circulator "Hey! Stop burning electricity to move cold water around, he's already too broke to stock up on fuel!"?

Also, I normally don't hear sounds of water going through the pipes when the circulator runs. The sound is similar to the way your 4" drain pipes sound in the basement when someone flushes above. It is heard loudest at the 90 degree bend immediately before the circulator. I'm assuming it's air in the pipes, but I just bled the system 4 weeks ago..
 
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Old 11-13-14, 04:58 AM
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Sounds like air in the pipes.
If you just bleed it, then that says there is air getting in somehow...
This = a repair bill.
There should be an aquastat to turn the circ on and off above a set temp.
With out make model / pics etc. its hard to know if there is one... but if it has been alright before then it should be ok now.
Not all boilers have them though, I know Burham gas fired do not.
 
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Old 11-13-14, 05:24 AM
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There is an aquastat. Honeywell L8148A
Taco 007-F3 circulator
Beckett A MP1192 Burner
New Yorker Boiler - Trying to make out the model number.. label is damaged

I was looking for a sticky on the approved and recommended method of posting pictures here. I know I saw one here somewhere
 
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Old 11-13-14, 05:56 AM
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The 8148A aquastat will run the circulator regardless of boiler temperature whenever there is a call for heat. If there's a call for heat but no fire, the pump will circulate cold water. What you observed was normal operation.

To post pics directly into the forum, there is an icon in the top bar of the reply window that looks sorta like a tree in a picture frame... click that and follow directions to upload pics. You can also use a photo hosting site such as photobucket.com and place a link to your pictures here.

I'm assuming it's air in the pipes, but I just bled the system 4 weeks ago..
What are both the temperature and pressure readings from the boiler gauge?
 
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Old 11-13-14, 06:14 AM
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Ok. Normal operation for that aquastat. Good to know. I need to get my float gauge in the tank operating correctly so I'm not caught by surprise so often. heh heh

It just shut off as I saw your reply NJ Trooper. The reading at that moment was 15psi and 180F.
It appears that the aquastat is set at 180 so I'm guessing that is why it shut off. The tridicator gauge looks horrible, but after creating my own gauge for testing as per your sticky, it's accurate.
When cool, it falls to about 2psi so I'm guessing I may be looking into replacing my old steel pressure tank with a bladder tank. But back to the matter at hand for now...
I didn't hear the sound once it was firing. I'm not sure if that was due to the noise of the burner being louder or not. Looks like the way to check it is to starve the burner again and send a call for heat.
 
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Old 11-13-14, 06:45 AM
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Last edited by NJT; 11-13-14 at 03:31 PM.
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Old 11-13-14, 07:03 AM
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Not necessary to replace the old tank with new, probably need to drain the old tank though...

And then figure out why your pressure is so low.

Actually, probably better to figure why the pressure is so low FIRST, because if you drain the tank, if you can't feed water to bring the pressure back up where it's supposed to be, you are in more trouble than you started with.

Find the water line that runs from your domestic to the boiler... is there a pressure reducing valve? (bell shaped valve) on it? Is there any manual shutoff valves on it? Can you take pic of what you find?
 
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Old 11-13-14, 07:23 AM
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I believe these are the fellas you're asking for:

Wouldn't they be malfunctioning if the pressure ever falls below 12psi? When I did the recent bleed, I had to run a bypass from the spigot of the water main to the spigot before the circulator to have enough pressure to bleed my 2nd floor radiators. I brought it to 15 for that. Once bled, heated pressure got up to 25 and climbing. I drained the tank completely then and was still dangerously close to 30 so I backed the pressure off with the spigot I filled at. Since then, the highest I've seen is early 20s. To be able to swing from a cold 2 up to a hot 25 seens screwy and worrisome
 
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Old 11-13-14, 03:26 PM
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Wouldn't they be malfunctioning if the pressure ever falls below 12psi?
I believe that's true.

Did you look for MANUAL shut off valves on this water line?

The valve to the LEFT is I believe an old style pressure RELIEF valve. This type of pressure relief is no longer up to code, and if my eyes aren't deceiving me, there is a PLUG in the bottom port of that valve... is that correct?

If that is true, PLEASE tell me that there is ANOTHER pressure relief valve on or near the boiler... one that looks somewhat like this:


image courtesy supplyhouse.com

Even if that other valve is not plugged, I would feel so much better if you told me that you had one of these on the boiler.
 
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Old 11-13-14, 03:29 PM
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I drained the tank completely
How do you know completely?

You shut the valve on the pipe leading to the tank, hooked up a hose to the drain, opened the drain.

Then what?

When the water stopped flowing you closed the drain and opened the other valve?

If so, you did not empty the tank completely. If you HAD, you would not still be having pressure issues.

There's more to draining that tank than meets the eye. I'll explain further in a later post after you tell me how you went about draining the tank.
 
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Old 11-13-14, 03:34 PM
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OK, you DO have another 'proper' pressure relief valve:



But what is NOT proper is the fact that this is not piped down toward the floor.

Heaven help anyone standing in front of that if/when it lets go. Time to call 911 for a trip to the hospital burn unit.
 
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Old 11-13-14, 03:36 PM
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This looks like the water line feeding the boiler, is it not?

Is that valve in the foreground OPEN or CLOSED?

 
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Old 11-13-14, 05:09 PM
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Did you look for MANUAL shut off valves on this water line?

The valve to the LEFT is I believe an old style pressure RELIEF valve. This type of pressure relief is no longer up to code, and if my eyes aren't deceiving me, there is a PLUG in the bottom port of that valve... is that correct?
Yes I did. There is one valve prior to the 2 red bell housing fixtures. It is open. After these fixtures, the water supply enters the 1 1/4" return/supply immediately before the circulator. There is a manual valve just behind that entry point which is also open (the return from rads). Immediately above that is a drain/fill valve which I have used to both to drain and fill. Those are the only manual valves on the water supply end of things. Here is a picture of what I just described:


To confirm, the valve to the left with the arm and spring on top is a Bell & Gossett A-8 30psi pressure relief valve. I do not see a plug on the bottom. There is a threaded hole on the bottom that is vacant. This is where water should come out if manually testing the valve with the arm.

The fixture on the right is a Bell & Gossett B-8 12psi reducing valve. It does have a plug on the bottom which I assume is a service port. If I understand posts from you to others correctly, I shouldn't even fool with trying to service it there and just replace it if faulty.

Given that the pressure falls below 12psi on the system, either the manual valve before these is faulty (unlikely, it's a simple inline spigot type valve) or the one of the 2 Bell & Gossett valves is clogged. I believe the galvanized pipe entering these to be near the end of it's life expectancy so I'm very nervous about replacing them. I've encountered a lot of fittings in other plumbing repairs here where some of the threads were rusted through. Moving along, I can manually fill to pressure via bypassing from the main supply to the drain/fill valve in the picture above which is what I did in order to complete the rad bleeding process. As long as the system doesn't leak/ maintains pressure, I'm fine with avoiding the valve replacement until the summer.
If that is true, PLEASE tell me that there is ANOTHER pressure relief valve on or near the boiler... one that looks somewhat like this:
Yes, there is. It appears you already discovered in the replies I'm hitting up next.

Whoah! Hold the phone... I lied above. The manual valve before everything was NOT open. Forgive that error. When open, it increases the pressure of the system to 10psi according to the tridicator. I had shut it off when the hot system pressure was reaching the mid to upper 20's. I have also developed a dripping leak at the stem of the large valve in the picture above when the first manual valve is open.
 

Last edited by djrobbaron; 11-13-14 at 05:21 PM. Reason: I'm an idiot and responded about the first valve from faulty memory instead of inspection.
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Old 11-13-14, 05:32 PM
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How do you know completely?

You shut the valve on the pipe leading to the tank, hooked up a hose to the drain, opened the drain.

Then what?

When the water stopped flowing you closed the drain and opened the other valve?
Yes, that is exactly what I did after looping the bypass to increase pressure for a complete bleed of the rads.

But what is NOT proper is the fact that this is not piped down toward the floor.
Duly noted, I'll pick up a 90 and a length of straight pipe to aim it at shoes instead of stomachs.

I've got to head out for work now until about 4AM. I'm more than a little nervous about the cold starting pressure being at 10. Hopefully the hot pressure while I'm out won't bust 30 and blow valves all over the basement office.
 
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Old 11-13-14, 07:09 PM
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I have also developed a dripping leak at the stem of the large valve in the picture above when the first manual valve is open.
Probably and easy fix. Just lightly snug the 'gland nut' which will compress the packing material a little bit more around the stem. Only tight enough to stop the weeping.

Duly noted, I'll pick up a 90 and a length of straight pipe to aim it at shoes instead of stomachs.
Thanks... that down pipe will also be a good place for a bucket.

There's more to draining that tank than meets the eye. I'll explain further in a later post after you tell me how you went about draining the tank.
What generally happens is that when the tank is drained, a vacuum develops inside and doesn't permit the rest of the water to come out.

If your drain hose is long and small diameter and probably looped around, air won't go back up the hose to break the vacuum.

Use as short and stout a hose as you own... or even cut an old one down... and leave the hose fitting on the valve a little loose so it can suck air.

I don't recommend this for sanitary reasons, but blowing into the end of the hose can sometimes break the vacuum. A small air compressor works MUCH better and prevents GI tract illnesses.

Sometimes removing the hose altogether and putting a bucket under the valve will allow the tank to gulp some air.

However you do it, you've got to get all the water out and the tank to atmospheric pressure before refilling the system.
 
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Old 11-14-14, 03:10 AM
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Thank you, that makes sense. I'll make sure to relieve the vacuum next time.

When I arrived back home, there was no call for heat and the pipes were still warm. I checked the gauge and found it was sitting at 11/12psi. When the call came for heat, it ran for an hour & 10 minutes before hitting 180. The pressure was 25psi when it stopped. This swing in pressure is better than the one I had experienced when I first improperly drained the expansion tank.

I would think that since the boiler is indoors and the pipes were warm when it started, the pressure wouldn't get any higher than 25psi. Thoughts?

Is the current 13-14psi swing way too wide? Will I answer my own question if I follow your directions for draining the expansion tank?

Keep in mind these other details about my system:
There is only one circulator, so one zone.
The house is a 2 story with a partial basement where the boiler resides. The radiators are all the old heavy cast iron type. The idiot previous owner painted all of them as well as their piping, giving me a nice (latex based I'm assuming) thin layer of insulator on them. There are 4 on the first floor and 3 on the second. When I bled the 2nd story radiators, they actually sucked in air. I had to use a fill loop to bring the pressure up to about 25psi run up, open one til it stopped, and repeat until I got a steady stream of water from the upper 3. I then rechecked the 4 on the first floor to make sure they still put out a steady stream.
Given this information, should my cool (at rest) pressure be high enough to push the column to the top? Or should I only increase it when I bleed the uppers?

My thermostat is set to send a call when the temp falls 2 below the target temp. As I stated before it ran for an hour & 10 minutes before it reached the 180 cutoff. I ran up to check the thermostat and it was .5 degree from the target temp. After a 5 minute bathroom layover, the still hot radiators had raised the temp the .5 degree to the target temp. If I'm not mistaken, the thermostat is set to end the call at 2 over target temp. If this last cycle is the norm, it would appear that the thermostat won't likely reach its upper limit. I'm trying to decide if "on by thermostat and off by aquastat" is the desired cycle. I was very disappointed that it took 1.16 hours to bring the house temp up 2 degrees. The resulting 3-5 gallons a day at over $3US will hurt like this winter... like over $2500 worth of hurt.

Thanks for all this help by the way!
 
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Old 11-14-14, 06:32 AM
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Since you have cast iron radiation you would greatly benefit from an out door rest control .
 
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Old 11-14-14, 09:15 AM
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I would think that since the boiler is indoors and the pipes were warm when it started, the pressure wouldn't get any higher than 25psi. Thoughts?
I'm not sure your line of thought here... Water expands almost 4% in volume when going from room temp up to 180, that's a given... sure, if the system is already warm, it's not going to expand as much when reheated because it never cooled and contracted fully.

giving me a nice (latex based I'm assuming) thin layer of insulator on them.
Surprisingly enough, the paint won't do much to hold back the heat.

should my cool (at rest) pressure be high enough to push the column to the top? Or should I only increase it when I bleed the uppers?
The entire system must always be at a positive pressure. The minimum cold fill pressure is pretty much standardized at 12 PSI, and is adequate for a 2 story building, but certain taller system require more cold fill pressure.

The formula : ( HEIGHT X 0.432 ) + 4 where HEIGHT is from the bottom of boiler to the top of the highest radiator, gives the minimum pressure required.
 
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Old 11-14-14, 03:18 PM
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When the call came for heat, it ran for an hour & 10 minutes before hitting 180
Rob, this is a problem...

It would seem that you've got a huge water volume, cast iron radiators, and no form of 'boiler protection' designed into the system.

I'm surprised that boiler hasn't corroded to a pile of rust from the inside out.
 
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Old 11-15-14, 08:13 AM
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The formula : ( HEIGHT X 0.432 ) + 4 where HEIGHT is from the bottom of boiler to the top of the highest radiator, gives the minimum pressure required.
That measurement for me is 17.5'
So 11.56psi?
That's reassuring. As soon as my new radiator key comes in, I'll test to make sure the top radiators push rather than pull at 12psi.

I'm hoping I was told wrong about the radiators being cast iron.

I'm surprised that boiler hasn't corroded to a pile of rust from the inside out.
You just brought to mind all the maintenance my cast iron cookware requires.

It would seem that you've got a huge water volume
The only way I can figure to nail that figure down would be to drain the system bucket by bucket. I'd imagine it would be hard to estimate. Especially not knowing how much corrosion is taking up space in the pipes, radiators, and boiler.

no form of 'boiler protection' designed into the system.
What is this protection you speak of? Links are welcome, I know these responses have to be time consuming.
 
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Old 11-15-14, 08:49 AM
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I'm hoping I was told wrong about the radiators being cast iron.
If they're 'standing' old-style radiators, they're cast iron.

The only way I can figure to nail that figure down would be to drain the system bucket by bucket
That's not necessary. If you've got large pipes and cast iron radiators, it's classified as a 'large volume' system.

not knowing how much corrosion is taking up space in the pipes, radiators, and boiler.
The problem isn't typically corrosion on the WATER side, but on the FIRE side.

With large volume systems, when a heat call comes and the burner fires up and water starts circulating, there can be cool water returning to the boiler for a long time.

This cool water coming back tends to keep the boiler iron cool, and below the temperature that water condenses out of the FLUE GASES. It's very basically the DEW POINT of the flue gas, which for oil fired systems is somewhere around 120F.

Flue gas condensate is ACIDIC and will slowly eat away at pretty much anything it comes into contact with... cast iron, flue pipe, chimney masonry...

ALL systems will produce some condensate on a cold startup, systems with fin tube baseboard heat up quickly and the return water is above the dew point quickly. It's the PROLONGED period of condensation occurring that becomes a problem over time with large volume systems.

How long might it take with your system before the boiler temperature is up to say 150F?

What is this protection you speak of?
They make big condoms for boilers.... DOHHHH! did I just say that? ummmm, sorry!

Seriously though, there are piping schemes that can protect a boiler from extended cool water return not allowing the boiler to come up to temperature quickly.

One that I feel is probably the easiest and least complicated to implement is this one:



The ESBE data sheet here, with more information:

http://s3.supplyhouse.com/product_fi...-Submittal.pdf

For your system I think I would recommend the 122F element:

193B1702 - Danfoss 193B1702 - ESBE VTC Temperature Element (122 F)

Here's the valve body:

193B1701 - Danfoss 193B1701 - ESBE Series 1-1/4" 3-Way Thermic Valve (Body Only)

I don't know that it would make much sense at this point to repipe your system with the old boiler, it's been there for how long? Whatever is done is done... Although repiping might save some fuel... maybe... probably...

Certainly if a new boiler is installed, it would be very wise to prevent damage... especially since newer boilers are more susceptible to flue gas condensation due to the lower temperatures of the flue gas (because they are typically slightly higher efficiency units).
 
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Old 11-15-14, 09:07 AM
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By the way, in the install sheet for the ESBE, the diagram on page 4 "VTC Thermic Valve on Gravity Conversion System" is similar to the diagram I posted, but in my opinion, can possibly lead to too much flow in the system.

The reason for this is because once the ESBE is fully open, the two pumps appear in SERIES.

Setting up what amounts to basically the same thing using the primary/secondary piping means that you get a constant flow through each loop. The flow in the primary doesn't affect the flow in the secondary, and vice versa.

As the boiler heats up, the hot water starts to be 'injected' into the radiator loop. Full flow in the system moves this heat all around the system. The ESBE will 'modulate', or 'float' between fully open and fully closed as the system heats up. The burner will NOT run continuously but will cycle on and off as the system comes up to temperature. An adjustable DIFFERENTIAL on the boiler high limit control would be a very good thing to have with this type of system. Increasing the DIFF to 20F or even 30F would mean less 'short cycling' of the burner. When the boiler hits 180, the burner would turn off and not fire again until the water cooled to 20 or 30 less...

Your existing aquastat is a fixed differential unit. I think like 8-10F ... which means short cycles.

The diagram on page 3, "Return Mounted (122F (50C), 131F (55C), 140F (60C) elements)" would not be suitable for a large volume system because although the boiler would be protected, it would take FOREVER to start getting any heat at all into the radiators.
 
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