pressure problems

mrfish

Have a new yorker fr 122 oil fired boiler. Single story home with cast iron baseboard. Extrol 60 tank. Circ pumping toward extrol tank. Worked good for 18 years with extrol 30. Recently tank and feeder failed.Upgraded to # 60. Pressure suddenly starting rising and relief valve opening. Suspected feed problem, not. Here's where it gets weird. First 60 psi incomming water pressure. With ball valve shut off to feeder, pressure rises to 14-20 psi. Run domestic water pressure drops to 0. Boiler runs for heat or hot water pressure rises again. I can't blame coil cause pressre will never excede 20 psi on boiler. I'm stumped, never seen this. How can we gain pressure with feeder off and then loose it during a DHW use?

JStar

You might...

...having a leaking DHW coil.

mrfish

mrfish

I thought about that but how can the presure drop to 0 and only build to 20 with 60 psi of incoming pressure?

Steamhead

Did they

check to see if there was enough air pressure in the tank? 

JStar

Gauges.

I never trust any gauges on the system. If the relief valve is blowing off, the pressure is greater than 30 psi. 

mrfish

mrfish

Yep--- double checked that. 12 psi.

mrfish

mrfish

When  the water feeder was open and operating and adjusted to 12 psi the relief valve kept opening. When the feeder valve was closed no more water at relief valve but how can we go from 0 psi to 20  psi and no higher and always go up and down with feeder off . I have been in the business for 40 years and this one is really weird. I have called several other plumbers and we are all stumped. I can see a pinhole leak in the dhw coil but cannot see it taking the boiler pressure to 0 when using water,

JStar

What happens.

If you shut off the cold supply to the coil and leave a hot faucet open?

mrfish

mrfish

I haven't tried that yet, I have to go there tomorrow so that might be worth a go, At this point I'm running out of ideas

Unknown

Seen similar scenarios,,,

If the tridicator & RV(as it should be), is mounted within the boiler I have seen situations where the RV will blow-off at 20 PSI.

Other guys thought-it was a defective RV & changed-it, still blew.

Turned-out the boiler "itself"  was getting plugged-up making the RV blow on temperature,, NOT pressure,,,, take a GOOD LOOK when you`re there tomorrow. :-)

Big Ed_4

No Expansion

Seems like the expansion tank is not in the system ....Check the tanks connection , could be plugged ., broken isolation valve, .is the tank installed between a flowvalve and zonevalves .. Just another thought..... . Boiler cools pressure drops , pressure rises when heated...