Why am I having a problem keeping pressure down in my boiler?

Joe.G

My auto feed stops at 12 lbs, And it will stay there intill my boiler kicks on then the pressure jumps to as high as 26 maybe higher on the pressure gauge then after it turns off it will drop back down to maybe 18 lbs after a while. The boiler is a old york heat boiler from 1947, I have a extrol tank #30, the motor on th eboiler is abecket that was replaced about 6 years ago. It never pops the blow vavle which I think is set at 30 lbs? Thanks
P.S the boiler works fine I have no complaints accept that it probably is not the most fuel efficent.

Bob Cat_4

Sounds like the blatter in the expansion tank is ruptured and needs to be replaced(the whole tank). If the pressure rises when you have the water feed off it is the expansion tank. It is safe to run your boiler with the water feed off for it is a closed loop system that does not require make up water.

Al Letellier

pressure build up

Don't, under any circumstances, run your boiler with the feed water shut off if it is not equipped with a low water cut-off that is in working order!!!!

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

tim from Reed Wright

pressure rising

I would suggest you put a larger expansion tank on, maybe an extrol #60. We have had bladder type tanks have problems after several years due to we think the bladders get stiff due to not having quite enough acceptance capability

Joe.G

I checked teh tank and there was 4 lbs of pressure in the tank but my friend did let air while we where changeing the copper pipes i filled it back up to 14 lbs and have not check it since(3 month? the tank only feels warm at teh top 1/4 of the tank.

Unknown

connection location

On some systems, I have seen the expansion tank on the boiler outlet (system supply) under an airscoop; the circulator on the boiler inlet (system return); and the fresh water feed valve connection on the return, on the SUCTION side of the circulator.

If the circulator is pumping into the expansion tank and pulling out of the feed valve, you can feed water in every time the circulator starts until the system pressure gets high enough to be equal to the lowest pressure the circulator dips to on startup. (whew!)

By accident of planning, this higher reading is the actual pressure that this system is designed to run at. You can set the valve to 12 PSI static, but the lowest pressure that valve sees isn't under static conditions. It is when the circulator first starts and spikes the pressure on the outlet side, which is held fast at what the pressure in the expansion tank is at that moment in time (not the precharge pressure). Since it can't rise on the outlet side , the suction side of the circulator drops, and the pressure reducing valve...feeds.

If the feed valve and the expansion tank were at the same point on the system, this couldn't happen.

Noel

heatboy

If the boiler doesn't reach 30 psi..........

while running, the compression tank may just be low on air charge. Is this a recent development or has it done this since the tank was installed? You didn't mention what the system heat emitters are, e.g., cast iron, fin tube, it could be the tank is just too small. Call your heating company and have them check the tank pressure (you must reduce system pressure to 0 psi to check if the tank is left on the system). There are formulas to calculate compression tank sizing.

It's impossible to tell what is wrong from here. You need to have someone look at it. Did you try "Find a Contractor"?

hb

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Leo

Joe, Bite the Bullet

Get a tech in to check your system and answer your questions. You have been here a few times with basic questions, that's good but if a professional had checked your system which I believe you have stated is oil the questions would be answered. At that point the system would generally be good to go for another year. A 1947 boiler is not efficient by todays standards. Has the burner been tuned and adjusted with instruments? Get these things done then come back and ask away. Remember any system be it gas or oil produces heat (fire hazard) and carbon monoxide. People work on their own cars but states have Safety Inspections. When people work on a heating system who inspects it?
I am not trying to insult you, I want to keep you safe so you can come back and ask questions.

Leo

Joe.G

I have had the boiler serviced every year sometimes twice a year, and everyone says the pressure is not a big deal as long as it does not pop the blow off vavle, it is not intill i have found this board that I see that you guys all reccomend a 12 lbs for pressure.
P.S my sytem has old cast iron raditaors. Thanks alot fo r the help for for teacching me a thing or 2.

ScottMP

Joe

As a rule of thumb I never install anything smaller than a #60 expansion tank with a system that has cast iron radiators. The volume of water is so large, a smaller tank cant handle the expansion.

Scott

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Joe.G

Do I have a problem? should I fix it? it has been like this for years now,(I don't know about the pressure but the setup has been) I plan on replacing it within a few years.What can the high pressure cause? and what is considered high? and what is considered to high? and what is considered normal? thanks

Joe.G

Do I have a problem? should I fix it? it has been like this for years now,(I don't know about the pressure but the setup has been) I plan on replacing it within a few years.What can the high pressure cause? and what is considered high? and what is considered to high? and what is considered normal? thanks

Joe.G

Is it dangerous? what could happen?