Help - water leaking from pressure release valve

ek99

Noticed some water leaking from pressure release valve whenever boiler is activated.  PSI on boiler is showing 50.

Turned off boiler, isolated expansion tank and replaced.  Noticed immediate drop in PSI down to 25.  All good.  However 2 hours later PSI on boiler is showing 40, with boiler still turned off. 

Does this mean my water intake valve is faulty?  It’s a Caleffi 553 auto fill valve.  Can I just replace the cartridge?  

Any thought greatly appreciated.  I have since turned off the water feeding the intake valve.    Thanks!!  

STEVEusaPA

Could be air, could be boiler feed, could be expansion tank has no charge it in, could be a combination of those.
Does your boiler also do domestic hot water...could be that.
25 psi is not 'All good' for almost all residential applications.

ek99

I guess I need to go through process of elimination.  

Expansion tank has 12 psi in it before installing.  So expansion tank definitely has charge. 

im thinking if I release water to let PSI reduce then shut off the water before auto fill valve.  If the pressure doesn’t rise then it must be auto fill valve?  

What do you mean Air?  Closed system with boiler turned off. 

Yes this boiler also feeds into domestic hot water heater. 

Thanks

ek99

I just checked the expansion tank for my domestic water heater has 0 psi.  So that is putting pressure back into the system?? 

STEVEusaPA

Got any pictures so we’re on the same page?

ek99

I figured out the problem.  The expansion tank replacement actually fixed the problem.  The abnormally high PSI on the boiler gauge after expansion tank replacement was due to a faulty gauge as it was showing 50 PSI,  after I switched it out the new gauge it now shows 15 PSI - which makes a lot more sense.   So this solves the heating problem.

however I now discovered that the expansion tank on domestic water heat exchanger is full of water and probably needs replacing as it’s showing 0 PSI.  I guess I’ll first try to drain the water tank then try to add some air to the tank.  If that doesn’t work I’ll need to replace. 

If my exterior hose pressure is 80 psi do I need to set the expansion tank pressure to 80? Seems high. 

Thanks

mattmia2

Is the water in the dhw expansion tank coming out of the schrader or is there just no pressure at the schrader? If there is water on that side it is done.

Jamie Hall

"If my exterior hose pressure is 80 psi do I need to set the expansion tank pressure to 80? Seems high. "

Yes. And it must be a tank intended for domestic water supply. They're very common -- almost any well water system uses one.

dopey27177

With 80 psi water pressure in the house it behooves you to install a pressure reducing valve to drop the water pressure to a safe pressure. Setting at 40-50 psi is a good place to be at.

Jake