still getting high pressure discharge

mark anderson

I have an older model forced hotwater system with cast iorn radiators (oil).

The pressure runs at about 30psi then discharges.

I put a new prv and flow control but problem still exsists.

I have the old steel expansion tank.

I would think that even if my tank was full of water or leaking that my flow control would not let the pressure raise to 30 psi!
Someone suggested going with a extrol but wouldnt it be better to just adjust the flow control?

THX
in advance

R Troughton

As water

heats it expands so...If your expansion tank is water logged then the pressure built from heating the water has nowhere to go.

This is assuming that the system is at 12psi or so cold and then builds to 30psi and blows.

If this is the case then you either need to replace the old tank with a new bladder style (ExTrol) or drain out the old tank and introduce some air into it. Does the old tank have an AirTrol setup on it? (Or similar)

I just re-did my system and tore out the old tank and added a FilTrol tank, which incorprates the feed valve also.

Rob

Bill NTSG

The problem

is your expansion tank. It is sometimes called a compression tank, what ever you call it, it is there to accept the expanded water.

It is a law of physics, when you heat a liquid , it expands in volume. You have a "closed " system , once you let the water in it doesn't get out. If your expansion tank is full of water, and you heat the boiler up , the only place the expanded water can go is on your floor via the relief valve.

This will happen with out your consent whether you think it should or not. Drain or replace your tank , Soon.

mark anderson

Many THX

I should know better. I will drain it and give it a few weeks trial period.

Many THX