Boiler Pressure Valves Keep Leaking

Adam E

Hi folks.

I've got a 24 year old Columbia boiler and I keep needing to replace the pressure relief valve. Over the last couple of years I've put on 3 new Watts 374As. Every time I pump the system up to 12lbs., it starts to piss it out like it was Pabst Blue Ribbon.

They were all pretty rusty inside when I replaced them. I guess the 374As weren't solid brass if they rusted. Would an M355 be better? Why do they keep failing?

Thanks!

-Adam

SlamDunk

You didn't say what the pressure relief valve was rated for. Sounds like 15psi in which case, that is not unusual, they start lifting before they reach 15.

Adam E

I assumed all residential relief valves were set to 30 psi (which mine is).

Jamie Hall

Adam E said:

I assumed all residential relief valves were set to 30 psi (which mine is).

Nope. You have to look at the tag or other rating information. The other -- obvious -- question is how accurate is your pressure gauge, and where is it located in relation to the location of any pumps and the relief valve?

HVACNUT

They're both 30 lb relief valves. If the pressure is ok then I would look at the water. Antifreeze, oxygen, pH, etc.

STEVEusaPA

Maybe your gauge doesn't work and you only think you are putting in 12 and your putting in 30.

Adam E

I never thought the gauge may be bad. It moves smoothly and consistently and the temperature side of it seems to work.

Do I have to cool and depressurize the system before replacing it?

Jamie Hall

Just as an hypothetical example... if we make several suppositions here... if your gauge and fill point and expansion tank are on the inlet side of the pump (where they should be) and the relief valve is on the outlet side (it should be at the inlet side)… and the gauge is responding, but not all that accurate and reads say 12 when the actual pressure is 20... then when the pump starts, the pressure at the relief valve could well jump to 25 or more, and the relief valve will weep...

As to cool and depressurize... probably, unless you should be so lucky as to have a valve on the gauge line. However, if you have everything all set to go, you won't have to fully drain the system. You'll get wet, but with everything on hand and ready to go, reduce the pressure a good ways, unscrew the old gauge and quick like a bunny screw the new one on. You'll still have probably gotten enough air in to want to purge, but it could be worse.

SlamDunk

Adam E said:

I assumed all residential relief valves were set to 30 psi (which mine is).

Mine relieves 15psi. guage is 30.

SlamDunk

Adam E said:

I never thought the gauge may be bad. It moves smoothly and consistently and the temperature side of it seems to work.

Do I have to cool and depressurize the system before replacing it?

I would never trust a five year old valve let alone a 24 year old valve. Most leak. depressurize the boiler. Just good practice.

Grallert

When the relief valve is leaking what is the gauge telling you? What condition is your Pressure regulator? will your PRV fill the boiler on its own? How is your domestic water heated?

Intplm.

@Adam E Do change the gauge. If for no other reason then for peace of mind, trusting a new gauge helps tremendously.

Then check your pressure reducing valve (prv).
Do you have antifreeze in your system?
Do you have a domestic hot water coil inside your boiler?
Is there a valve that feeds the boiler(fast feed) leaking by ever so slowly?

I had a piece of a old relief valve float in and out of the discharge of a new relief valve. It made the relief act just like yours.
When you change the relief valve, be sure to blow water out the port before installing the new one just to make sure there is nothing in the way as has happened to me.

Hope this helps.

Adam E

Thanks all.

How do I know what length stem I should get on my new gauge without removing the old one first?

STEVEusaPA

Why don't you just get a 0-30 or 0-60 pressure gauge you screw onto the hose bib to check your regular gauge? Then if your gauge works, you don't have to change it.

Adam E

Grallert said:

When the relief valve is leaking what is the gauge telling you? What condition is your Pressure regulator? will your PRV fill the boiler on its own? How is your domestic water heated?

I have no regulator - manual only. Also, I have a coil in the boiler for hot water.

I just filled it up to 12 lbs. and let it dribble down till it stopped. The dripping stopped when the gauge read zero. Then, I tried to bleed my cast-iron baseboards and nothing came out. No air, no water, no nothing. All of my radiators are less than 8' above the outlet of the boiler so I shouldn't need much pressure, but it seems I have none.

For now, I guess I'll replace the relief valve and Tridicator to get me through the season and start thinking about a new boiler...

Thanks.

SuperTech

Add a fill valve please. It could be that your ridiculous manual fill valve is leaking and overpressurizing the boiler.

If you are going to shut down the boiler and drain it, you might as well make it right before you refill it again. No point in doing it half ****.

Grallert

How about your expansion or compression tank? Really you should invest in a pressure regulating valve. Better yet a combination pressure regulator/backflow preventer. As well as a new gauge of some kind. This way you will have a reasonable idea of what's going on in your boiler.

GBart

Really you should invest in a professional hvac technician, you're obviously missing something.

I think the net could be used to ensure you aren't getting ripped off, but sometimes you actually need a pro to look at it. You're looking for the magic "hey somebody on the net save me money for free" answer

so what do you do for a living? can I get your service for free?

pecmsg

SlamDunk said:

Adam E said:

I assumed all residential relief valves were set to 30 psi (which mine is).

Mine relieves 15psi. guage is 30.

15 is Steam
30 Hot Water

The 30 should be Temperature and Pressure

GBart

pecmsg said:

SlamDunk said:

Adam E said:

I assumed all residential relief valves were set to 30 psi (which mine is).

Mine relieves 15psi. guage is 30.

15 is Steam
30 Hot Water

The 30 should be Temperature and Pressure

No, wrong, residential boilers are pressure only, water heaters are T&P or temp and pres and are usually 210F and 150 PSI, commercial boilers can be higher ratings of pressure.

Jamie Hall

Gentlemen. I presume. Meaning @GBart and @Adam E . If I may say so, both of your are making remarks and comments which are not in keeping with the character of the Wall. Perhaps you would care to reread them and edit them?

STEVEusaPA

@Adam E Your last remark is rude and will probably get you bounced.

Yes it is called HeatingHelp emphasis on 'Help' but I do agree with the philosophy of @GBart . Sometimes the best 'help' is to get a professional in, especially when it comes to life/safety issues.

With things like this, 15 people will go back and forth asking dozens of questions, when a pro, at the site, can solve this rather easily and quickly.

Considering all equipment needs maintenance and most likely eventually, repairs, finding a competent pro to work on your equipment is well worth the price. It's good to have a relationship with that person when the heats off and it's sub-freezing.

A problem like this with an oil boiler, brought up at an annual maintenance for one of my customers would be quick and easy and not very expensive at all to fix. And not too expensive for a service call. For my better customers, if no parts were needed and just a proper purge, I usually do it for free.
Who knows what other deficiencies could be discovered and fixed, saving the H/O money over the long run.

Filling/purging a boiler and eliminating air problems can range from the very simple to the very complex, with huge penalties for not enough water, too much water and the dreaded dry firing.
Plus who knows the level of skill of the homeowner. Break something with a hot boiler and it's big trouble.

I've enjoy helping people here and out in the field. I enjoy helping and learning from other techs.
But I have been backing away from h/o who just don't have the tools, skills and knowledge to work on their own heating systems when it comes to life/safety components-especially with oil burners and people who just don't/can't do a proper combustion analysis and set up their burner properly. It's not about money or proving I know what I'm doing, or protecting some 'secret' skills. I treat people here the same way I would treat someone calling me on the phone about a problem. And 99% of those are "Let me come out and take a look".

It doesn't help if someone asking for help for free throws a tantrum. Part of the internet world we now live in-get info free & fast.

HVACNUT

Do you know the pressure on the air side of the extrol tank?
Drop the boiler pressure, remove it and check it. It should be pressurized to 12 psi.
But like the other guys stated, replace all water parts, even if just to update.
Extrol tank, 30 lb relief valve, air eliminator(s), add a pressure reducing valve and back flow preventer, and tridicator gauge. (Long or short is the distance between the boiler jacket and the boiler, not insertion depth)
I might say theres a pinhole leak in the domestic coil but too long a period of time between leaks I think.

Intplm.

@HVACNUT your right about all of the above. But one thing that is probably happening regardless of how long is the last thing to look into, and that's the domestic HW coil. It's probably leaking too. More then likely the last thing to find however.

SuperTech

You can check if it's the tankless coil by shutting down the valves on it and seeing if the problems continue. Either way you are much better off not using a tankless coil for DHW, it's the least efficient way to make hot water. An indirect tank is your best option, a tank style water heater is another option.

GBart

Let's look at some facts.

This isn't This Old House, it's one thing to say "hey Joe how do you frame a picture"? or "my stair squeaks when I step on it", This IS HVAC, This is DANGEROUS, So I firmly believe we need to call it at some point in the help phase and not everyone here giving advice is a trained HVAC technician.

HVACNUT

Slow down there cowboy. Its Friday. This is a leaking 30 lb relief valve. No gas, oil, electricity or plutonium involved. And the OP was wise enough to come here for help.

Jamie Hall

GBart said:

... not everyone here giving advice is a trained HVAC technician.

True. I'm not, for instance. Just an old knuckle dragging Registered Professional Engineer. Does one have to be, a trained HVAC tech. to give good advice? No Does being a trained HVAC tec. guarantee good advice? I think some of the disasters we see on the Wall speak for themselves on that. So relax. Speak to what you can, extend help where you can, warn where warning is necessary. And relax.

Erin Holohan Haskell

We agree that there are times when it is absolutely necessary to tell a homeowner to call an HVAC tech. We even have a Find a Contractor section on the site to help them reach experienced pros.

We do not, however, tolerate disrespectful comments and foul language. If you're looking for a fight, you will not find one here. As per site rules posted in the link at the top of the page (and agreed upon when you sign up): "Please be respectful of others. We reserve the right to remove content and disable accounts when we believe content or behavior is harmful to this online community."

Tinman

Right on, Erin. And, Heating Help is here to...help.

Erin Holohan Haskell

Steve Minnich said:

Right on, Erin. And, Heating Help is here to...help.

Yes, it is. Thank you, @Steve Minnich.