Boiler blow off problem

Eric_13

Here is one I am running out of ideas.

Three Hydro Therm boilers together for a condo complex. The pressure reliefs are blowing off slightly. I have replaced all pressure reliefs. The pressure goes to 40 lbs, even with the water feed replaced and the isolation valves shut off. There is no water being allowed into the boiler. When the pressure is at 40 you can open the relief and a small amount of water comes out. Nothing like it should be with the PSI behind it.

The pressure slowly but surely will get back to 40lbs. The exp tank fills up every time and I drain it and pressurize it to the recommended pressure.

The only thing that I can figure out why this is happening is the 20 GPM Everhot might have a pinhole on the domestic side.

Does anyone think that I am on the right track to replace it??

Your help is much appreciated in this matter.

Alan(CaliforniaRadiant)Forbes

Undersized

x-tank?

Before you replace the indirect, try the next larger size expansion tank.


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J.C.A._3

> x-tank?

>

> Before you replace the indirect, try

> the next larger size expansion tank.

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 53&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_

J.C.A._3

What type of expansion tank?

For 3 boilers tied together, is it large enough?

Got any numbers? Frankly, I'd be more suspect of the feeder allowing water in at a snails pace. ( a bit of crap pulled in during installation has bitten me more than once.)

Ahh, the things you learn after 20 years. Good luck. Chris

Unknown

You are right

about the pressure on a relief valve at 40 psi . Just a tiny flick of the pop-top and water should fly out of there . Problem is , is the relief valve set to blow at 30 psi ? Did this happen with the new relief valves installed ? In any event , there should be more force behind that kind of pressure . Did you happen to change the gage also ? Maybe you can check with another gage that spins on a boiler drain ?

If the pressure is climbing when the PRV valve is shut , I would guess it's the Everhot leaking into the boiler . Is there a way to isolate the Everhot and check ?

You also say you have to drain and pressurize the expansion tank . What kind of tank is it ? You think it might be undersized , like Alan said ? Is this a recurring problem ?

Ken_8

There's only two possibilities...

Either the indirect(s) are allowing city water pressure to weap into the boiler water side of the HX's, or the expansion tank has a pin-hole leak that's letting air out and "flooding."

Best test would be to simply turn off the feed water stop/valve with the expansion tank filled with a reasonable amount of air at operating temperatures. If the pressure goes up, the indirect is leaking city water into the boiler side of the system. If the pressure goes down - the expansion tank has a leak above the water line and is allowing air to escape.

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Dale

Broken union

If you have a pressure rising without the boilers not running problem I would cut a union and anothe valve into the water feed line to eliminate the inlet water feed leak possibility, if water drips out of the union the problem is in the normal feed. If it's dry then the more expensive coil must be the source. Let us know what you find.