boiler ?

efrancis1 · November 28, 2014, 12:30am

need some info from my fellow inspector on this,

My friend has a boiler in his house from 1950’s
overflow tank, and many shut off valves some within a foot of each other that are very corroded.

there is a TPRV that is blowing every 30 sec. to one min, because of the pressure being so very high.

which in turn is filling a 5 gallon bucket in a half day.

one question is, if the corroded shut off values could be causing the pressure to build up, do to lack of flow through the pipes.

or could there be another reason for the high pressure?

the boiler is not very big, about the size of a 40 gallon water tank,
with an expansion tank of about 10 gallons.

any information in regard to boilers from the 50’s would be great.
thanks.

Happy Thanksgiving

dokeefe · November 28, 2014, 12:49am

The expansion tank may be filled. The heated water does not have anywhere to go but through the pressure valve. One explanation.

efrancis1 · November 28, 2014, 12:51am

thanks David,
do you know what a fix for that would be,
a bigger expansion tank?

lkage · November 28, 2014, 2:25am

As David said, the tank diaphragm is probably compromised and water logged and needs to be replaced. Or it is not charged with the correct amount of air.

wwilson3 · November 28, 2014, 3:02am

Change the tank , you drain for the night but it needs replacement , is there a place to add air to the tank?

jjonas · November 28, 2014, 8:44am

What type of boiler, and what type of system does the home have? Too many possibilities to guess on a MB. Could just be a bad TPRV. Call a service tech to check it out before the thing blows. The TPRV discharge is your first and maybe only warning. Don’t ignore it!

agriffin · November 28, 2014, 1:52pm

Just saw a boiler where the pressure reducing valve going into the boiler had failed, which was causing the boiler tprv to go off (30psi tprv). What pressure is the boiler running at?

efrancis1 · November 28, 2014, 2:16pm

Thanks for the replies, answers to follow.
The tpr valve was just replaced.

sparksnmore · November 29, 2014, 5:00am

Sounds like maybe it’s a typical old hot water heat system with a water logged expansion tank.
Those old expansion tanks did not have a bladder so the need to be drained every fall to be replenished with air.
IF so, shut off the inlet valve and drain the tank completely.
The tank will have a cushion of air for expansion as the inlet water compresses air above it as it enters.

The automatic fill valve lets water into the boiler until the pressure reaches 12PSI cold then as the water temperature rises, the pressure will usually get up to around 18-20PSI. if the expansion tank isn’t water logged.

What happens with a water logged expansion tank is, the pressure relief valve lets out water when the pressure gets up to 30PSI, then the next time the boiler cools down, the pressure drops and the auto fill puts water back in to start the cycle all over again.

efrancis1 · November 29, 2014, 6:02pm

sparksnmore:

Sounds like maybe it’s a typical old hot water heat system with a water logged expansion tank.
Those old expansion tanks did not have a bladder so the need to be drained every fall to be replenished with air.
IF so, shut off the inlet valve and drain the tank completely.
The tank will have a cushion of air for expansion as the inlet water compresses air above it as it enters.

The automatic fill valve lets water into the boiler until the pressure reaches 12PSI cold then as the water temperature rises, the pressure will usually get up to around 18-20PSI. if the expansion tank isn’t water logged.

What happens with a water logged expansion tank is, the pressure relief valve lets out water when the pressure gets up to 30PSI, then the next time the boiler cools down, the pressure drops and the auto fill puts water back in to start the cycle all over again.

Thank you, for your comment.