system prssure

[NCFord]

I am been running my storage since last week and loving it! I think my pressures are normal, but don't really know what normal is. Static pressure at room temp is 12psi and when I get storage up to 180 top and about 160-170 bottom the pressure is about 25-26psi. Are these normal?

 

[maple1]

That's getting pretty close to blow off pressure I think.

Mine runs from about 8 depleted (130/110 +/-) up to about 12 charged (190/175 +/-), at the guage on my boiler supply/out fitting. What do you have for expansion? Not saying it's 'too high', but it's higher than I would run - actually I think my boiler valve would blow off before it got that high. It's a Euro version but I think it pops at 22psi.

 

[NCFord]

I thought it might be a bit high too. I know my expansion tank is not oversized, I have been keeping my storage temps at 170 or below which keeps the pressure well below 25psi. I might need to add another smaller expansion tank.

 

[Coal Reaper]

my system runs from 10psi cold to 20psi hot at the boiler.

 

[NCFord]

Ok, here is one other thing I can't explain. I have 2 pressure gauges near the boiler, one on the boiler itself and one on
top of a small pressure tank( I think an extrol 60). When the boiler and tanks are up to temp about 170, the pressure near the
boiler is only about 20 psi while the pressure in the storage tanks is about 25psi. My much larger expansion tank(I can't remember the model, but I think it's a 62 gallon tank) is located near the storage tanks which are just across the room about 25 feet. The pressure gauge on the storage tank is mounted about
halfway up on one of two vertical 250 gallon propane tanks. I don't know why there is such a big difference.

 

[Coal Reaper]

i added a gauge on top of my boiler facing the door to boiler room so i can see it from outside and it is a few psi off from the gauge on the boiler itself. i know i bought a cheap one so i only use that as a reference. also, you will lose almost 1psi for every 2' increase in vertical. i think it is said you should have 4psi at the highest point in your system.

 

[maple1]

From my experience, pressure guages should initially be regarded as suspect. Seems to be quite a wide variety in accuracy. I've got 7 (I think) scattered around my system.

I just lit a fire 10 minutes ago. Tanks were 135/125 (probes at middle of each horizontal tank). Guage at my boiler outlet was at 8psi. I've got another guage right beside it on a fitting on the front of the boiler, the needle in it was resting on the stop. I think that's around 5 psi. Over time & by comparing all my guages, I've concluded that one reads low. I've got another one on my boiler return fitting, which is 3' or so (?) below my supply fitting one, and it reads 1-2 psi more than the one on the supply fitting. So they seem pretty good, and are the exact same make/model of guage, and compare well with the other ones.

I'll pay more attention to pressure once I get things heated up, and post back if I se anything much different than the 12 posted above - I actually haven't given them much more than a casual glance for quite a while, so not sure now exactly what it tops out at.

EDIT: Re differences, height will affect at about 0.4psi/foot of rise, and also if pumps are running you would see lower PSI on the suction side than the discharge side of the pump. Not sure how much, maybe a couple PSI?

 

[Coal Reaper]

you will also learn through experience roughly how much wood to load in boiler to bring it to full charge based on where your pressure needle is sitting

 

[NCFord]

coal reaper I don't know exactly what the 4 psi at the highest point in the system means but my pressure gauge on the tanks is 4 feet below the top so that could add a
few psi. I don't have a reason to dought the gauge its a high quality one. Do you have a pressure gauge near or on your storage tanks? Perhaps
most folks don't bother to install one on the tanks, I also installed a second 30psi boiler relief on the tanks.

 

[NCFord]

Ok I was a couple of post behind with my last post. So the new gauge could be off a bit because the other two are exactly the same and the location of the gauge on the tank could account for the difference. Thanks

 

[Coal Reaper]

quick read gives the gist: (broken link removed)
doesnt have to be BB, just the highest point water needs to flow to.
i have gauge on boiler, on top of boiler, and on oil boiler in house ~10 below wood boiler.
the varms blow off at 21.8psi i believe.

 

[NCFord]

Thanks, I think the highest point in my system is the top my tanks or perhaps the tops of the tanks are level with my heat exchanger.

 

[stee6043]

I routinely hit mid 20's when my system is maxed out at temp. I've never had an issue. 190 top to bottom on my tanks will push me to 26/27 psi on a "decent" temp/pressure gauge. When my system is cold in the fall I'll start out at 12psi +/-...

 

[BoiledOver]

This system has 2-500 gallon stacked and slightly oversized expansion, has 12 psi @ 80F and runs about 20 psi @ total charge 190F.

Initially was using some Honeywell tridicators, cripes they are junk. One showed over 40 psi, another 32 psi and the other never went above 15 psi. Was scared for a while. Anyway, changed out with some Wika pressure only gauges and am very comfortable with their readings. Readings at 5 feet above floor and top of storage vary by about 3 psi. Ya get what ya pay for in gauges.