Boiler Relief Valve Problem?


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Old 11-10-11, 02:25 PM
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Boiler Relief Valve Problem?

Hello, I just noticed a leak from my boiler today. It must have been leaking for at least a couple of days now. It's coming from the relief valve discharge line.

I did some research and checked the expansion tank for excess water/inadequate air and I think it's fine(12psi like on the stamp).

When I tested the relief valve the water was pretty dirty the first time. I've never discharged any water before today(had the system for almost 10 years now). The first time the valve took a long time to close, the rest it seemed to shut quicker. I've noticed the gauge next to the valve at 20 and sometimes closer to 25 psi.

I'm assuming I need to replace the relief valve? If so, how do I know if I need the Conbraco 10-407 or 10-417(the tag only says 10-400 series)? Is there anything else I can check? Any input would be appreciated, thanks!







I also noticed this on the other side...

 
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Old 11-10-11, 02:31 PM
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I forgot to mention it's a pretty steady/consistent drip from the discharge line now.
 
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Old 11-10-11, 02:58 PM
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In cases like this, it's always the SAFEST bet to presume that the relief valve is leaking because of overpressure (doing it's job) and that the pressure gauge is inaccurate. Always err on the side of caution!

Even so, a 10 year old valve is due for some preventative maintenance. Our friend Furd and I both feel that these valves should be replaced regularly. NO ONE ever does though!

So go ahead and replace it anyway... it's time. We'll talk about the gauge in a later post.

Just what exactly IS that on 'the other side' ? Looks organic!

Apparently a leak. (ya think?)

I can't see enough of that to tell exactly where it's leaking though. Is that a valve of some sort under all that 'mung' ? Can ya get a closer, larger pic of that?

When yer changing the relief valve, might as well fix that at the same time!

When you checked the pressure in the expansion tank, did you relieve the pressure on the boiler water side first? That is a MUST or you won't get an accurate reading on the tank air charge.

Oh yeah, the relief valve model... the 407 would be the one that you have. You don't have to stick with Conbraco... Watts, McDonnel Miller, Taco, I'm sure there are a dozen others... what you need is the 3/4M X 3/4F 30 PSI valve... FIXED, not adjustable.

As long as it has the right threads and pressure, you are good to go.


If that tank has been installed as long as the relief valve, then I would bet two cases of beer that you have less than 5 PSI in that tank!
 
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Old 11-10-11, 03:23 PM
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Thanks for the quick reply! Responses in bold:

Originally Posted by NJ Trooper View Post
In cases like this, it's always the SAFEST bet to presume that the relief valve is leaking because of overpressure (doing it's job) and that the pressure gauge is inaccurate. Always err on the side of caution!

Even so, a 10 year old valve is due for some preventative maintenance. Our friend Furd and I both feel that these valves should be replaced regularly. NO ONE ever does though!

So go ahead and replace it anyway... it's time. We'll talk about the gauge in a later post.

Just what exactly IS that on 'the other side' ? Looks organic!

Apparently a leak. (ya think?)

I can't see enough of that to tell exactly where it's leaking though. Is that a valve of some sort under all that 'mung' ? Can ya get a closer, larger pic of that?

Unfortunately I can't, the setup is boxed in by the wall, a filing cabinet, and piping. From what I can see it's just pipes and then that black round handle at the end.


When yer changing the relief valve, might as well fix that at the same time!

Absolutely, I will have to move the filing cabinet and inspect further.

When you checked the pressure in the expansion tank, did you relieve the pressure on the boiler water side first? That is a MUST or you won't get an accurate reading on the tank air charge.

All I did was shut off the main water valve and ran the sink in the basement for a bit. When I went to check the pressure, a little water sprayed out of the nozzle, but none after. I had a bike pump and tire gauge, after I pumped it it said 15 psi on the tire gauge so I aired out until it reached 12. How do I relieve pressure on the boiler water side?

Oh yeah, the relief valve model... the 407 would be the one that you have. You don't have to stick with Conbraco... Watts, McDonnel Miller, Taco, I'm sure there are a dozen others... what you need is the 3/4M X 3/4F 30 PSI valve... FIXED, not adjustable.

As long as it has the right threads and pressure, you are good to go.

Solid, thanks!


If that tank has been installed as long as the relief valve, then I would bet two cases of beer that you have less than 5 PSI in that tank!

Haha yeah I believe the whole setup is original parts AFAIK! I will check again once I learn how to relieve the pressure on the boiler side.
 
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Old 11-10-11, 05:06 PM
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When you checked the pressure in the expansion tank, did you relieve the pressure on the boiler water side first? That is a MUST or you won't get an accurate reading on the tank air charge.

All I did was shut off the main water valve and ran the sink in the basement for a bit. When I went to check the pressure, a little water sprayed out of the nozzle, but none after. I had a bike pump and tire gauge, after I pumped it it said 15 psi on the tire gauge so I aired out until it reached 12. How do I relieve pressure on the boiler water side?
The fact that you got a 'little' water out the air valve and not ounces of it may (or may not) mean the tank is still OK. It's still possible that the tank should be replaced.

Shut off boiler and let cool for a while... don't want to burn yourself with 180 water...

Somewhere on the piping should be a 'water feed valve' ... you will need to close that valve. This will allow you to drain a little water off and drop the pressure in the boiler without it trying to refill itself as you drain.

If you can pull back with the camera and get some wider angle shots from a few different angles, I might be able to spot the feed valve and tell you which one it is. Ditto for the drain valve.

Then, you need to take a garden hose and connect to a BOILER DRAIN. Running the water in the sink won't help, the water in the boiler is completely separate from the domestic water supply.

Put the garden hose in a bucket, laundry tub, floor drain, etc, and open the boiler drain with the hose and let ONLY ENOUGH water our of the boiler until you see the pressure gauge go to zero.

Put your tire gauge on the expansion tank valve and check pressure...

Here's a step by step write-up I did a while back that might be helpful:

The idea of repeating the steps is because if the tank was really low on air, it will be full of water. When you pressurize the tank that water pushes out into the boiler and raises the pressure up again... add air / check boiler pressure / drain a little more / check air / add a little more / lather, rinse, repeat.

=====================================================

1. Shut off boiler and allow to cool to under 100F.

2. Shut off water supply line to boiler.

3. Drain only enough water from the boiler drain to drop the system pressure to ZERO. REPEAT: DO NOT COMPLETELY DRAIN THE BOILER! ONLY ENOUGH TO DROP THE PRESSURE TO ZERO!

4. With an ACCURATE tire pressure gauge, check the air charge in the tank on the air valve opposite the end of the tank that's connected to the system. If ANY water comes out of the air valve, the bladder inside the tank is shot and the tank needs replaced. If no water comes out the air valve, and the pressure is less than 12-15 PSI, continue to step 5. If the pressure is OK, turn the water supply to the boiler back on and repressurize the system, turn the power back on to the boiler, no service is necessary.

5. Using a bicycle pump, or a small air compressor, add air to the tank until you have 15 PSI air charge.

6. Check the boiler pressure gauge again, and if it has risen off ZERO, drain some more water from the boiler drain until it is again at ZERO.

7. Check the air charge on the tank again. If it is below 15 PSI, add air to the tank until it is at 15 PSI.

8. Repeat steps 6 and 7 until the boiler stays at ZERO and the tank stays at 15 PSI. At this point, the tank is properly recharged and the water supply can be turned on to re-pressurize the system, turn the power on to boiler and return to service.

=============================================

So let us know how ya do, and post more pics if possible.
 
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Old 11-10-11, 05:59 PM
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Alright thanks a lot for the tutorial! Here are some more pics of the setup(I took tried to get angles of all the handles/levers and hose connections):



 
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Old 11-10-11, 06:30 PM
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I still can't tell what that crusty thing is... but what you see there is the result of a long term very slow leak. The hot water leaks out, evaporates quickly, and leaves behind any minerals in the water... (calcium, magnesium) ... as a fluffy whitish / greenish crust. It grows over time.

The second pic... to the left of the 'Watts 9D backflow preventer' ... there's a red handled ball valve (quarter turn to close) ... that's your water feed valve. That's the one you need to shut off the feed water.

The first three pics show those two red handle hose bibs. You could put your drain hose on either of those.

A couple observations:

The photo might be misleading as to the distance, but those cardboard boxes behind the boiler are a 'no-no'. There should be a respectful distance from the boiler to any combustible items. I would remove those and leave a space all around the boiler.

The two green pumps up near the ceiling are mounted improperly.
Excerpt from the installation instructions ( http://www.taco-hvac.com/uploads/Fil...ry/102-054.pdf ) follows:

INSTALLATION:
1. Mounting position Circulator must be mounted with the motor in a horizontal position. It may be mounted vertically with the motor up, provided that the system pressure is at least 20 psi (138 kPa).
The fact that they've worked all these years makes me wonder why the manufacturer says that it shouldn't be done...

The water drips down the side of the expansion tank tell me that the 'float type automatic air vent' (the small brass can thing) on top of the 'air scoop' (the hunk of cast iron that the expansion tank hangs from) is now or has been leaking. The cap on the top of that vent device is normally left loose in order to vent the air it catches. If it's leaking water (even if it evaporates before it drips) it should also be replaced.
 
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Old 11-10-11, 08:14 PM
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I still can't tell what that crusty thing is...
Looks like a mixing valve to me.

Its a combi boiler I believe.

http://www.gogeisel.com/geiselonline...BP_EDP_EDN.pdf

Mike NJ
 
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Old 11-10-11, 10:59 PM
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Originally Posted by lawrosa View Post
Looks like a mixing valve to me.

Its a combi boiler I believe.

http://www.gogeisel.com/geiselonline...BP_EDP_EDN.pdf

Mike NJ
Yup, it's the heat and hot water one.
 
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Old 11-10-11, 11:02 PM
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Alright I will test the tank again tomorrow. Maybe those pumps have worked all these years because the pressure stayed above 20 psi? It's currently at 16 psi...

edit: Another question: In this link it says a symptom of a faulty tank is "hot to the touch lower than the middle of the tank," but my tank isn't warm anywhere. The pipe it's connected to is, but not the tank itself. Is that a sign that something's wrong?
 

Last edited by NJT; 11-11-11 at 02:23 PM.
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Old 11-11-11, 05:10 AM
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Originally Posted by Blueprint99 View Post
edit: my tank isn't warm anywhere. The pipe it's connected to is, but not the tank itself.
Scratch that, just checked again this morning and it's warm on top and cool on the bottom so hopefully that's a good sign...
 
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Old 11-11-11, 02:44 PM
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Alright I will test the tank again tomorrow. Maybe those pumps have worked all these years because the pressure stayed above 20 psi? It's currently at 16 psi...
I don't think that's it, because the instructions say:

It may be mounted vertically with the motor up,
and yours are mounted with the motor DOWN.

I believe that Taco's reasoning is that the bearings in the motor assembly would suffer undue wear when mounted with the motor down, and UP is OK as far as the bearings are concerned, but they spec the 20 PSI because in that position the pump would be prone to 'cavitation' with lower pressure. That's the best explanation I can come up with... in any case, motor DOWN is a no-no...

If those pumps were to be turned 90 so the motor is horizontal, would there be room between the two pipes for the one pump? Reason I ask is that these pumps are available with a flange that's rotated 90 and if you do have to replace them at some point it would be an easy 'fix' to buy the pump with the rotated flange... as long as there would be room for it between the pipes.

edit: Another question: In this link it says a symptom of a faulty tank is "hot to the touch lower than the middle of the tank," but my tank isn't warm anywhere. The pipe it's connected to is, but not the tank itself. Is that a sign that something's wrong?
Yeah... well... that's sorta true. Take a look at this brochure to understand why someone might say that... the reality is that this form of diagnostic is not really accurate. I would venture to say that even if there were no air left in the tank the bottom still wouldn't get hot... and remember, this is for a tank that is properly mounted with the air valve DOWN. NOT true for a tank improperly mounted with the air valve UP.

Oh no... dangit, Amtrol redesigned their website and brochures, and now I can't find the old brochure with the excellent explanation as to how these tanks work! DANGIT!
 
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Old 11-11-11, 03:55 PM
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Originally Posted by NJ Trooper View Post
... in any case, motor DOWN is a no-no...

If those pumps were to be turned 90 so the motor is horizontal, would there be room between the two pipes for the one pump? Reason I ask is that these pumps are available with a flange that's rotated 90 and if you do have to replace them at some point it would be an easy 'fix' to buy the pump with the rotated flange... as long as there would be room for it between the pipes.
Thanks for clarifying! It might fit, but it's looking tight. This is a huge surprise as my parents had the system "professionally" installed back in the day. I'm pretty sure those pumps have never been touched, but I'm assuming they're still working(probably not 100% by now) since we have heat and hot water.

Could I just flip them so the motor is facing up if they won't fit horizontally? Or how about turn them each 90 degrees in the opposite direction?

How would I know if they need to be replaced?
 
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Old 11-11-11, 04:59 PM
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Or how about turn them each 90 degrees in the opposite direction?
Probably could... if ya got room on both sides.

This is a huge surprise as my parents had the system "professionally" installed back in the day.
If they're still around, don't tell them. And if the pumps are still working, let them work. Yours isn't the only one that's this way... and again I question how important it really is after seeing so many that have worked so long installed this way.

How would I know if they need to be replaced?
#1 response: If they aren't working!

Bad motor, bearings, might make noise, get super hot, that sorta stuff.

Don't sweat it... just know that if they fail, you have options to 'make it right'.
Even if the 007 Taco don't fit, you can get other pumps that are a bit shorter motor, like the Grundfos 15-58... it's a little more compact. I think all manufacturers have 'rotated flange' models available. They want to sell you a pump!

I'm sorry that Amtrol brochure is no longer available... but maybe they'll respond to my email... and put it back on the website.
 
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Old 11-11-11, 07:36 PM
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I believe that Taco's reasoning is that the bearings in the motor assembly would suffer undue wear when mounted with the motor down, and UP is OK as far as the bearings are concerned, but they spec the 20 PSI because in that position the pump would be prone to 'cavitation' with lower pressure.
More likely the opposite. With the motor mounted vertically up the upper bearing would likely run hot and prematurely destroy itself. Remember that these "canned" pumps use the circulating water to cool and lubricate the bearings. With less than 20 psi in the system there would be a large enough air bubble in the upper bearing area to preclude any circulating water. Above 20 psi the air bubble would be small and not unlikely to be eventually absorbed.
 
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Old 11-13-11, 07:20 AM
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Originally Posted by NJ Trooper View Post

Then, you need to take a garden hose and connect to a BOILER DRAIN. Running the water in the sink won't help, the water in the boiler is completely separate from the domestic water supply.

Put the garden hose in a bucket, laundry tub, floor drain, etc, and open the boiler drain with the hose and let ONLY ENOUGH water our of the boiler until you see the pressure gauge go to zero.

Put your tire gauge on the expansion tank valve and check pressure...

Here's a step by step write-up I did a while back that might be helpful:

The idea of repeating the steps is because if the tank was really low on air, it will be full of water. When you pressurize the tank that water pushes out into the boiler and raises the pressure up again... add air / check boiler pressure / drain a little more / check air / add a little more / lather, rinse, repeat.
The leak from the relief has slowed down considerably but it's still dripping a bit, so I finally started this.

Like you said, the pressure I'm pumping in is gone as soon as I drain the boiler again. I drained it to 0 psi, pumped the tank to 15, drained again and the tank pressure goes back down to 0 psi along with the gauge on the system. I've done it three times with the same results(doesn't seem to be holding any pressure after I drain it)-just wanted to make sure I can keep repeating without causing any damage or if these results prove the tank is no good. I just pumped it back up and turned everything back on for now. After turning the system back on the gauge reads 18 psi.

Just for the hell of it I got a quick clip of the tank/gauge setup. The drain in the end is the one I used.

Pipes - YouTube

another question: could a bad tank be the cause of that leak/buildup in the back on the other side?
 

Last edited by Blueprint99; 11-13-11 at 07:26 AM. Reason: Another question
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Old 11-13-11, 07:27 AM
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I would say from your post the expansion tank is shot. Water will probably come out of the schrader valve of the expansion tank if you try to release some air out.

Mike NJ
 
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Old 11-13-11, 07:52 AM
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I sure wish I could get that diagram from Amtrol, because I think if you could see that you would understand better what's going on...

Hey, Watts has a page with a diagram! This is specifically targeted at domestic water heaters, but the principle is exactly the same. Look at this:

Thermal Expansion - Learn About - Watts

If your tank has a busted bladder, or completely lost it's air charge, that tank could be FULL of water. As you add air, it will push that water back into the system so you will see the system pressure rise. The idea of repeating the steps is so that you can get the water out of the tank and replace it with the correct air charge.

If after pumping up the tank to 15 you see the boiler pressure rise to 15 then it's a sure bet that you did have very low air, and tank full of water.

If after dropping the boiler to zero again, the tank air charge went all the way to zero may in fact mean that the tank is shot.

When you added the air to the tank, and then dropped the boiler pressure to zero again, did you hear air gurgling out of the tank and into the system? You should not have, because as you can see from the diagram, the air and water should not mix.

How old is the tank? 10 years you said I think? If it has never been maintained, then it's a fairly good bet that the tank is shot. When the air pressure in these tanks is not maintained, that bladder inside is stretched WAY out of shape... way past it's design parameters... and it's not IF it will fail, but WHEN...

I would suggest at this point to simply replace the tank. They should be available for about $35 or so at HD or Lowes. The new tank will (should) be precharged to 12 PSI, but CHECK IT before you install it.

You will probably have to drain part of the system... at least drop the pressure to zero... if you don't drain it and can work fast, you may be able to change the tank by just dropping the pressure to zero, but you WILL lose some water... best advice is to drain, at least partially, and cover stuff with plastic sheets... you don't want water in any controls (or all over the floor for that matter).

That tank will be HEAVY when you remove it! It will be full of water! Don't be misled by the weight of the new tank! BE PREPARED FOR THE WEIGHT! Maybe 30-40 POUNDS...

This graphic shows some OPTIONAL items you can install when you replace the tank. You will probably have to drain a bunch of water from the system.



Yes, ANNUAL (at least every TWO years, no more) maintenance of the tank pressure. These tanks DO LOSE 1-2 PSI yearly... and if checked and adjusted regularly, the tank will last a LONG TIME! (I just changed my own, which was installed for about 25 years, and still functioning... I just got tired of looking at it)

There's a BALL VALVE, and a DRAIN valve added between the tank and the air scoop. With these in place future maintenance of the tank is GREATLY improved! Just close the ball valve, hook a hose to the drain, drain the pressure from the tank and add air as needed. When charged, just close the drain and open the ball... DONE.

Same goes if you have to change the tank, close valve, drain pressure, change tank, and back in service. No more draining the boiler to change the tank.

You can put this together with 1/2" black pipe nipples, and threaded valves.

Here's a pic of mine, in copper... and a few extra goodies, but you get the idea:



By the way, that ball valve... you do NOT want that type... I built mine with 'stuff' I had laying around (surplus, free). That valve is expensive! You just need a standard 1/2" ball valve.
 
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Old 11-13-11, 08:20 AM
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Ok thanks guys, a new tank it is. The diagram definitely helped my understanding of the situation.

So if I replace the tank, do I still need to replace the relief valve?

Also, should I have someone look at the back corner with all the buildup, the part lawrosa identified as a mixing valve, before I replace the tank or can that wait until after?

Any chance you have any links that would help explain what's going on with that mixing valve?
 
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Old 11-13-11, 08:34 AM
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So if I replace the tank, do I still need to replace the relief valve?
I would. You'll have the system drained anyway.

Also, should I have someone look at the back corner with all the buildup, the part lawrosa identified as a mixing valve, before I replace the tank or can that wait until after?
Draining the system... might want to do it at the same time, BUT... if that valve is for your DOMESTIC hot water supply, you might could do that at a different time because you might not have to drain the boiler for that if it's domestic water supply. I don't think either Lawrosa or myself are SURE that's what it is anyway. Need to KNOW before messing with it!

Any chance you have any links that would help explain what's going on with that mixing valve?
Without knowing exactly what it is, no... but here is some info on what a 'mixing' or 'tempering' valve is and does.

Anti-scald valves, tempering valves, mixing valves on hot water systems and at plumbing fixtures
 
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Old 11-13-11, 09:05 AM
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So if I replace the tank, do I still need to replace the relief valve?
YES! The seat and disc on the safety valve has no doubt been eroded by the leaking and WILL continue to leak. Safety valves should be replaced as a matter of routine maintenance every five years.
 
 

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