The Case of the Snapped Relief Valve, This weeks case for Friday

RayWohlfarth

The maintenance tech was called to the job for a water leak in the boiler room. When he arrived, the entire top of the relief valve was snapped off. After shutting off the valves to the boiler, he texted me pics of the relief valve and asked me to pick one up. The top of the relief valve was laying on the floor still attached to the copper discharge piping. What caused the relief valve to snap like that? This case had two contributing factors which caused the safety valve to fail. I will let you know Friday morning at 6am EST

pecmsg

Over tightening the valve to the boiler then overtightening the copper to the valve without a backup wrench.

JUGHNE

Relief valve was dripping/weeping.

Discharge pipe was piped outside to freezing temps, the end froze shut.

The water was pressurized just like a cracked wall hydrant that had the hose left on in the winter.

ethicalpaul

That is a great idea @JUGHNE! but he said in his description that the valve part was lying on the floor with the discharge piping attached. That doesn't sound like something that was plumbed to outside.

I'm leaning toward pecmsg's idea about over-tightening being one of the factors, but I can't think of the other factor.

Maybe the boiler room itself got very cold and the short pipe to the PRV froze causing a crack, but the boiler itself didn't. Then some time later a high pressure event occurred that popped it off (like an expansion tank failure etc)

Steamhead

Hot water rather than steam?

ethicalpaul

I assumed it was a hot water system since the initial call seemed to be a water leak in the boiler room

dko

Expansion tank failed
copper discharge pipe was plugged/capped in some way

mattmia2

boiler failed during an extended vacation of some so so wasn't noticed, boiler room got cold enough to freeze the relief valve, probably from the make up air openings, because of the mass of the boiler the relief valve was the first to freeze, then the warmer water from the municipal supply kept the boiler warm enough to keep from freezing once the relief valve popped off.

HomerJSmith

There are different kinds of PRVs, some with diaphragms and some without. I'm trying to visualize what could cause that, but mystified as to how the discharge pipe was with the top of the valve, lying on the flr since the discharge tube is connected to the lower part of the valve. Could be a cracked housing.

Myself, I tighten a PRV until it cracks and then give it one more turn. Works for me.

EdTheHeaterMan

There may be a mechanical advantage when the grandson was riding his tricycle around the basement. Grandchildren can play with a significant amount of force against a 3 or 4 foot safety drip tube attached to the pressure relief or safety valve. The reason I stated it this way is because no competent adult would admit to pulling on that pipe as a handle for helping themselves up from a kneeling or sitting position on the floor near the heater. 'If they would only use bigger fonts on those warning labels, I wouldn't need to get on the floor to read them."

dko

There isn't a relief valve that has any kind of joint between the outlet and inlet threads so when he says the entire top snapped off its probably a male outlet relief valve. And that it snapped right above the male threads?



So I'd agree with overtightening being one of the factors or dezincification weakening the threads?

ethicalpaul

@EdTheHeaterMan I swear to goodness that my very first thought was a kid on a tricycle riding past it and hitting it with his rear wheel. I guess we both must have had lots of playtime in basements!

EdTheHeaterMan

ethicalpaul said:

@EdTheHeaterMan I swear to goodness that my very first thought was a kid on a tricycle riding past it and hitting it with his rear wheel. I guess we both must have had lots of playtime in basements!

Did your basement also have a swing attached to the basement ceiling joists? With a ping pong table at the other end?

HomerJSmith

Don't you think water should be pouring on to the boiler room flr? This should have been a catastrophe.

EdTheHeaterMan

HomerJSmith said:

Don't you think water should be pouring on to the boiler room flr? This should have been a catastrophe.

First line of original post.

"The maintenance tech was called to the job for a water leak in the boiler room"

Third sentence says

After shutting off the valves to the boiler...

My response to your statement:
"Yep sounds right" Maybe that is why the customer called in the first place!

Still want to know about @ethicalpaul's basement as a kid. Do we have more in common? I know that his mother and my mother were both mothers! And we may have grown up in different neighborhoods together.

HomerJSmith

Water should have been flowing with a broken PRV. However, the boiler supply could have been turned off, but the tech turned it off or, perhaps, the tech responding to the drip out of the PRV the PRV was broken by the tech, himself or by the homeowner or maintenance guy. Hmmm Ya! Something doesn't jive, here.
I'm sure it will all make sense on Friday.

EdTheHeaterMan

Still confused by the acronym PRV. What does the Pressure Reducing Valve have to do with this? Or is that acronym interchangeable with Pressure Relief Valve? Homer, your responses bring up more questions that they answer. That is what I like about you! So perfunctory to the point of pococurante laodiceans in an enthusiastically accurate proclamation of approximately irrelevant information.

HomerJSmith

Thank you, thank you very much. I don't know what you said, but thank you. Ya. Pressure Relief Valve-Pressure Reducing Valve both PRV, the meaning is in the context.

RayWohlfarth

Happy Friday. In this case, there were two problems. The first was that the compression tank was flooded. This caused the relieve valve to open and close. The relief valve was piped to a copper tube and piped solid to the floor. Each time the valve opened, the discharge pipe would expand. Since one end was piped to the floor, there was nowhere for the expansion so the force was directed at the brass relief valve. This constant movement caused the relief valve to snap and flooded the boiler room We had to drain the compression tank and cut the discharge pipe to allow for expansion. Thanks

RayWohlfarth

Oops Here is the link to the video

https://youtube.com/watch?v=oirjJ8bkLuE

dko

I would have liked to see the actual snapped relief valve

RayWohlfarth

@dko I wish I still had it. It was on an old Blackberry that I traded in without getting the pictures

JUGHNE

So was the new valve installed and piped just like the old one??

If so then waiting for the comp tank to be water logged again.

Why not just drop straight down to 6" above the floor?

A dripping valve would be noticed right away.

I have seen a few relief valves piped this way, always on commercial jobs that were engineered.

The drawing showed piping right to a floor drain with a 90 pointing down or even thru the floor drain grid screen. One would not notice dripping thru the pipe.

One such installation cost the owner several hundred gallons of glycol mix as the auto fill kept adding raw water. They had been ill advised to keep the water supply connected to the system. LWCO was in place.

HomerJSmith

Ya, constrained expansion is a problem. Kinda like, am I getting bigger or is my pants getting smaller. hmmm
Thanks, Ray.

RayWohlfarth

@JUGHNE No we changed it to allow an air space.
@HomerJSmith I have the same feeling when putting on mine LOL