High pressure in hot water furnace

beginner

30 lbs. should be the right reading if your expansio tank is 30#. Take it look at your pressure relief valve rating. It should be rated at 150psi. You may need to replace it.

Larry Chappa

Running too high

I have a Crown gas fired hot water boiler and under fire the gage goes to about 30-35 pounds and my relief valve lets go and water is released,also hearing noises when circulating. This furnace is only 7 yrs old.Today i blead the 3 zones to get all the air out and started the system and the gage on the furnace read about 12 pounds. When i returned about 20 min later the gage was reading a little over 30pounds and water blew out all over from the safty valve. This furnace has given me problems since it was almost new. HELP

lchmb

expansion tank

Assuming it was heating back up when you left, it sound's like your expansion tank may have lost air, needs to be set at 12 pounds... If this has been an ongoing issue it may be that the tank is not sized properly.

If the boiler was not running for heat and gained water cold it could be the fast fill is failing and over pressurizing the system.

lchmb

not a hot water heater..

He has a boiler not a domestic hot water heater. The PRV should be a max of 30 pounds...

beginner

My bad. Jump the gun too soon.

beginner

What is the rating of the expansion tank?

lee_7

what kind of expansion tank do you have, an old style steel tank or a bladder style tank?

Larry Chappa

My expansion tank is about a year old and has 12 lbs pressure. I did fill the boiler cold. Also the water feed valve does not seem to stop filling now so i shut off the incoming water to the boiler. I am reading almost 20 pounds on the gage and the system is not running. The feed valve is not old either. I cant seem to stop the valve from feedig water other than shutting off the water to the furnace

lchmb

either

Either the valve has failed or the auto feed lever is in the up (on) position. I would set the pressure to 12 pound's cold. Make sure all the zone's are purged completely, shut the auto fill off, then turn the boiler on for heat. It should run up to temp and your pressure should increase to the 20 pound area. If it run's by this it's possible your expansion tank is undersized....

Larry Chappa

How do you set the pressure on the feed valve? Maybe i should just replace it

Unknown

you may not

You may not get it fixed properly if you keep calling your BOILER a furance!...

Tombig_2

Boiler pressure

Larry, either your PRV (fill valve) is passing feed water or you have an expansion tank problem. fill the boiler to 12psi cold and DON'T fire it. Does the pressure creep up? The problem is in the PRV. Yes you can adjust it but that's best left to a pro.

If it's the expansion tank (pressure rises after firing) we need more info. If you've had ongoing issues with your boiler maybe you should find a pro near you at this site and do it right once and for all.

Larry Chappa

My expansion tank is a year old and it has 12pounds pressure in it.I checked with a good tire gage.The gage on the furnace reads 20 and rises under fire.The releif valve let go and i had water on the ground.I think the ,feed valve is set too high,I think the furnace should be about 12pounds cold.I will try to replace it.

heatguy

call somebody

you are in over your head call someone. if temp and pressure go up same time. close boiler feed valve bring system to 12 psi, fire boiler let it come up to temp if you go over 25 psi your expansion tank is the issue

Brendan_4

How are you makeing domestic hot water?

[Deleted User]

And a #60 expansion tank is for 60 psig?!!? I don't think so.

[Deleted User]

You can't check the pressure in your expansion tank with pressure on the system. Call a professional.

#1 plumba

do u have an indirect hot water heater? that could be the problem, maybe a hole in the coil bringing in street pressure....call a pro, your just gonna spend more money changing stuff out even if u dont have a water heater connected to the system.