Hot and Cold Boiler pressure

[Perfect Heat]

I pressurized my system to 15 psi when I filled my boiler. When fully heated (190 degrees) the pressure would go to 20-22 psi. Now that I am firing less I notice the cold pressure goes down to 5 psi or even 0 if I have not fired for a week. Once I fire the pressure goes back up to 15 or so. Is this normal?

Thanks

Terry

 

[taxidermist]

No you have a leak somewhere. I just had this same problem and it was a pump seal leaking, it took a few days to get to zero so I never noticed it until I recharged the system and started to check for leaks. I also had a small leak on the ball valve stem on my pump isolation valve. I just tightened it and all is well. I just fired back up my boiler today.

Rob

 

[Perfect Heat]

Thanks
I checked and there was a small leak at one of the fittings. I guess when it was firing the water probably evaporated. When summer arrives here I will be able to drain and fix.

 

[webie]

I am not sure how your sytems are set up but mine is plumbed right into my domestic water via a backflow and pressure reduceing valve . So unless you are shutting your water off to your domestic water supply which is a no no you should always have some pressure . Now after saying that my system cold is about 7lb's and hot about 15lb's

 

[taxidermist]

I am not sure how your sytems are set up but mine is plumbed right into my domestic water via a backflow and pressure reduceing valve . So unless you are shutting your water off to your ot doing it the riestic water supply which is a no no you should always have some pressure . Now after saying that my system cold is about 7lb's and hot about 15lb's

Yep your right!! I do not have mine plumbed into my DW I did not to do this so I know if I have a leak somewhere. I know why you did it that way so we dont have to spank Rob for not using a BFP and auto fill.LOL


Rob

 

[Perfect Heat]

Mine is also not plumbed into the domestic water system. I have a low water cutoff on the boiler itself in the event a leak goes un noticed.

 

[ChiefChicken]

If your system comes up to 20 psi @ 190° every time you heat it up, chances are you don't have a measurable leak. Mine has been doing the exact same thing for years. If the system doesn't come up to your "normal" psi at a given temperature, then you know to start looking for a leak. I have mine plumbed into the domestic water supply (via backflow and pressure valves) but I normally keep the supply valves shut so that my heating system remains isolated. Many people find this to be a good idea because you can routinely monitor system pressure to check for leaks. On the other hand, if you leave the valves open and have a constant supply of makeup water, you will never notice a leak until you see it coming out of your ceiling or across your floors. If you do decide to run with the valves closed, be sure to have a low water cutoff plumbed into your boiler system.

 

[heaterman]

If you are getting pressure variation which goes up when hot and down when things are cool the expansion tank is probably too small. It's normal to see the system pressure rise a couple PSI form room to operating temp but if you are getting over 4-5PSI increase you need a larger or an additional tank.

 

[vvvv]

If you are getting pressure variation which goes up when hot and down when things are cool the expansion tank is probably too small. It's normal to see the system pressure rise a couple PSI form room to operating temp but if you are getting over 4-5PSI increase you need a larger or an additional tank.

+1?

 

[heaterman]

If you are getting pressure variation which goes up when hot and down when things are cool the expansion tank is probably too small. It's normal to see the system pressure rise a couple PSI form room to operating temp but if you are getting over 4-5PSI increase you need a larger or an additional tank.

+1?

???

 

[Perfect Heat]

Once I validate I have no leaks and the proper size of expansion tanks should the pressure stay within a couple of psi. Say I have it set at 15 psi cold. When fired it should only go to 17 psi or so then back down to 15 psi when cold or not in use for extended periods of time.

Thanks

Appreciate the feedback

 

[taxidermist]

If you are getting pressure variation which goes up when hot and down when things are cool the expansion tank is probably too small. It's normal to see the system pressure rise a couple PSI form room to operating temp but if you are getting over 4-5PSI increase you need a larger or an additional tank.

Your the boiler man but I would think more like no more than 10psi not a couple psi. I see a 10psi increase and I have 2 large 60 (I think) exp tanks for my 1000gal storage. I shoot for a max temp of 180* with a pressure of 20 to 25psi.

Rob

 

[in hot water]

when you calculate expansion tanks the programs will generally tell you the expected pressure increase from coldest to warmest operating temperatures. Type of fluid is important also, glycol needs more expansion "space"

hr