Pressure relief valve question

mattj815

Hi everyone. Just had a question on an issue I had to deal with today.

First I just wanna say thanks because I only post here when I have a problem because I really have no knowledge to contribute lol but everyone is always so helpful. So thank you

So I just recently bought a new (to me) home. It has a pensotti on demand heater. I guess the feed valve was not working corr3ctly because every few weeks the heat would cut out and the display would show "h20". So I would manually fill the boiler using the tab on a taco feed valve.

So this morning the wife called me and said the heat shut off and I instructed her what to do. Shes done it before with no issues but this morning when she did it. She said water was coming out. I had her shut the water and I came home to check it out.

So when I checked the feed valve it had no tension to it and was just moving freely. So I thought it was shot. Which was ok bc as far as I knew it wasnt working correctly anyway.

Went to depot, bought a new one and installed it. Went to valve the water back in and it came shooting right back out a pipe facing the floor.

So I opened the cover and found what im guessing is the pressure relief valve? I played with it a little, first opening the silver tab up and of course more water came out. Then I pushed it closed and it stopped. Boiler kicked on and I have heat again. Yay

My questions are: are these resettable? Or should I replace?

And im guessing it blew because when my wife tried to manually fill and broke the feed valve it flooded and released the extra h20? Am i correct in thinking that?

Also I dont really know much about this boiler. I took the model.# and am gonna look for.some info after I post this. But theres no gauge for pressue or water level. Just a gauge with red and green indicating.good.and no good im guessing. And i assume its for the water because it moves as I manually fill.

Any tips on how I should maintain this? Hopefully the new feed valve works as it should and I shoudnt have to do much. Well see!

Jamie Hall

Can you tell us a bit more about this? Which model Pensotti is this? Gas (I presume?) or oil? And this is used for heating the house, not the domestic hot water?

Then... the pressure relief valve should not trip, but it may be -- if this is for heating -- set for 30 psi, so a bad feed valve could easily overpressure the system and trip it. If it's holding now, you don't have to replace it... though it's not a bad idea.

What really bothers me, though, is that you have to add water to the boiler from time to time. You shouldn't, if it's heat only. So we need to know more...

HVACNUT

Like @Jamie Hall wrote, you shouldn't need to add water periodically, or ever really, if the PRV is working properly.

Is there any portion of the house where piping runs under a concrete slab, or in a crawlspace?

mattj815

So it is gas heating. The hot water is a seperate unit. Its model # pch 18/b.

Like I said im hoping the feed valve was bad and hoping that since I replaced it I dont have to manually add water to the system. But like I said every 3-4 weeks since I moved in (oct 19) I would get "h20" flashing on the boiler display and would have to fill in order to get the boilet to fire.

So do the feed valve and pressure valve work in conjunction with one another? I just assumed the feed valve was responsible for providing water to a system that needed it. But I guess maybe it would get that from boiler pressure.

Eta. Curious at what temp should the boiler be operating? The display is in celsius but there is a conversion chart on the front right now its about 80c.

hot_rod

The expansion tank could be shot, waterlogged, so the relief pops occasionally then needs to have water added?

Any sign that the relief valve has discharged?

Got a pressure gauge on the system?

mattj815

Theres one gauge I see with a red bar then green then red again. With the green ranging from 7.2 to 21.5 psi. 14 in the middle. This is coming from a manual I found online.

Should I just swap out the expansion tank? Theyre cheap enough right.

So hotrod, youre saying the x tank could be the reason to replenish? Am I correct that possible the feed valve broke and water was flooding the tank and coming out of the outlet of the relief valve?

EBEBRATT-Ed

@mattj815

About 15 psi is what the boiler should have for pressure when it's cold. It is normal for the pressure to rise when the water is heated but if it gets over 25 you probably have a bad expansion tank.
\Try this: Turn the boiler off and let the boiler and system get down to room temp 70-80 degrees is good enough.

Get the boiler to 15psi and shut off the water feeder. You can buy a gauge and a fitting and install one on your boiler drain valve if needed. A 0-30psi gage is good.

Turn the boiler on and crank the thermostat up run the boiler until the system and all zones are up to temp 180 degrees or so

Keep and eye on the pressure. If it rises over 25 you expansion tank is likely bad

HVACNUT

If you need to add water to your closed loop system, then the system is losing water.

Turn off the manual valve before the PRV and sooner or later the burner circuit will open again on low water.

Unless the LWCO is not installed correctly and sits in an air pocket.

mattj815

> @EBEBRATT-Ed said:
> @mattj815
>
> About 15 psi is what the boiler should have for pressure when it's cold. It is normal for the pressure to rise when the water is heated but if it gets over 25 you probably have a bad expansion tank.
> \Try this: Turn the boiler off and let the boiler and system get down to room temp 70-80 degrees is good enough.
>
> Get the boiler to 15psi and shut off the water feeder. You can buy a gauge and a fitting and install one on your boiler drain valve if needed. A 0-30psi gage is good.
>
> Turn the boiler on and crank the thermostat up run the boiler until the system and all zones are up to temp 180 degrees or so
>
> Keep and eye on the pressure. If it rises over 25 you expansion tank is likely bad

Thanks. Ill look into doing this if i can get a gauge somewhere tomorrow. But for $30 bucks or so. Would it be worth it to just change the expansion tank?

mattj815

> @HVACNUT said:
> If you need to add water to your closed loop system, then the system is losing water.
>
> Turn off the manual valve before the PRV and sooner or later the burner circuit will open again on low water.
>
> Unless the LWCO is not installed correctly and sits in an air pocket.

Yea i dont know where id be losing water. I dont think i see a manual valve before the prv. The prv is inside the unit. So it goes valve on the cold water inlet, boiler feed valve, into the unit to what looks like a pump, then routes to either the prv or further into the boiler.

HVACNUT

What's the model number?

Jamie Hall

There better not be a valve before the PRV!

The point is -- if you are having to add water to a hot water heating system, either the expansion tank is so gone that you are overpressuring the system and losing water that way, or you have a leak. You need to check both possibilities, as has been suggested.

HVACNUT

> @Jamie Hall said:
> There better not be a valve before the PRV!
>
>
Sorry Jamie. My PRV stands for Pressure Reducing Valve, not Pressure Relief Valve.