Expansion tank ... good or bad?

woobagooba

Boiler's pressure relief valve has be spitting lately and looking a bit crusty. Replacement is on the way. Not sure if the Extrol 30 expansion tank is good or bad. Sounding the tank ... seems to indicate it is full of water ... https://share.icloud.com/photos/0Lg8UVQY60_rOo13Zeo2g9-QA

But quick check at the Schraeder valve hisses dry air.

?

Cheers

STEVEusaPA

You can only check the tank with no pressure on the system.
Drain the boiler, disconnect the the tank and check the pressure.
Then repipe the tank out of the way and add a Webstone Expansion Tank valve so you can always check it easily without draining the system.
Banging on the tank is a fool's errand.

HomerJSmith

Dry air is good. It means that there is no water getting by the diaphragm. However that doesn't mean that there is the proper acceptance of boiler water space in the tank. What does the tridicator gauge say the pressure is when the boiler is cold? Air pressure in the tank maybe low.

It could be a faulty pressure relief valve. too. If you replace the PRV, check the air pressure in the tank and set it at 12-15 psi. Do this while the sys is drained.

woobagooba

OK to all of that. Will look for a warmer day to drain the system, replace the PRV, relocate and check the (cold) expansion tank pressure, add the Webstone valve. Current location of the tank is a PITA re: inspection.

System is currently running a bit north of 20 PSI.

Intplm.

20psi at full temp should be fine for now. A better psi is at 12-15 with the air charge of your tank at the same.
While you are doing this work it may be a good idea to change your gauge too. It will help to make sure what you are reading is correct/without error.

woobagooba

Replaced the PRV and expansion tank today. Sure enough, the tank had about 3 gallons of water in it. Thanks all.