Pressure problems

plumbgolf

I changed out a Burnham boiler and customer called me back that the relief valve was leaking. Extrol tank has been changed 2 times and is set at 12psi, relief valve has been changed 2 times, PRV is set to 12 psi and has been changed with 3 different makes. It has an indirect water heater when the water is off to the boiler the pressure stays between 12 & 25 psi so it isn't the indirect. when the water is turned back on to the boiler the pressure starts to rise. I'm stumped on this one anyone got an answer? Thanks

icesailor

Pressure Problems:

You have an indirect. You have a cold start boiler. If you have a #30 Amtrol or equivalent, it is probably too small to take care of the expansion. You need a #60. Or, add a #60 to the mix. There isn't enough expansion to take care of the thermal expansion from your cold start boiler/system. \

#30 Extrols are usually too small for cold start systems. Read the instructions for sizing them.

Ron Jr._3

Easy way to check

to see if it's not enough expansion tank -



Make sure tank is set to 12 psi. and boiler temp is room temp . Then crank it up to the high limit . See how much the pressure increased . Anything over 20 and I'd add more tank capacity .



What kind of hea tin the house ? Large volume of water ? And what size tank ? 15 is marginal even on smaller homes .  

billtwocase

where

is the extrol located, and what size? It is odd that the feed won't stop, but the tank is possibly isolated between a flow check and zone valves or an IFC pump?  Post some pics

Brad White

What is

the system volume?



I agree with Ron Jr.



If your system fluctuates between 12 and 25 psi as a normal range, your tank is too small. I suspect it is connected to an older gravity system?



When you eliminate the fill valve and indirect as variables but the system has that wide a pressure range, volume comes to mind.



My own system is primarily and old gravity system and I have two #30 tanks. The system height is 27 feet and my cold fill pressure is 18 psi, the system rises to 25 when hot so I may even install a third #30. System volume is about 85 gallons as a point of reference.



My $0.02

icesailor

Pressure Problems:

I learned that lesson well way back when when I did as I was taught, use a flow check (SA-1 1/4) as an ell, install the air-scoop and extrol. Then, I started using Taco 571 zone valves. It isolated the system from the Extrol. Leaving the flow check solved the problem. IFC's in circulators could be a real problem. Like if they are there. 

billtwocase

Ice, usually what happened

was the house was originally 1 zone pump and flo check, then they added on or something and needed to zone it off. The flow check was left inline, but not opened so the expansion tank/extrol could do it's job. He may need a 60, but need to know more. For most residential, 30 can be oversized, so I'm still doubtful. I am guilty because I never found that15 lasted. Bad enough the 30's and 60's are living a short life

icesailor

Under Pressure:

Brad, rather than add a third tank, why not add a #60. I do it all the time. It works nicely.

Brad White

Third Tank

Hi Icesailor-



The cost of a #60 is more than twice the cost of the #30 and in my case they fit better. Tank volume is tank volume, so it is really just logistics.

Also, you are an installing pro, I am not. Your labor is worth more than mine, doing work for myself. So from a professional and overall price-competitive view, a single tank makes more sense, I agree!