Boilers - Home Heating Steam and Hot Water Systems - xpansion tank pressure

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refer guy
12-21-06, 09:07 AM
hello, if my expansion tank pressure is 12psi,and my boiler water pressure is 18,do i have to add alittle more air pressure to the tank?thanks


NJ Trooper
12-21-06, 02:41 PM
hello, if my expansion tank pressure is 12psi,and my boiler water pressure is 18,do i have to add alittle more air pressure to the tank?thanks

Depends... how did you measure the expansion tank pressure ?

Is that boiler pressure cold, or hot ?

If it's a big enough tank, you probably wouldn't have a problem. It could have the reserve capacity to handle the expansion. If the tank is marginally sized, you could see the pressure go up too high when the system got hot, possibly high enough to pop the 30 lb relief valve.

But, if it ain't broke... ;)

KField
12-21-06, 06:42 PM
If you didn't take pressure off the boiler, the tank pressure and the boiler pressure will be the same. The boiler pressure gauge is probably not accurate. The expansion tank pressure should be between 12 and 15 psi.

Ken