What should my pressure be?

Hey folks

Just lighted the stoker today for the first time and now heating the house and domestic water with it. Keeps the boiler temps set to my aquastat (150-170) and kept fire on this warm day with the timer. Im wondering what the pressure should be. It seems to hover between 20-25 pounds.... is that too much? Seems to me the 1300 in the shop stays between 15-20.

I know that 30 is too high and that is what the popoff valve is set at..... but so far it has not come over 25 pounds.

Let me know what you think. The whole system seems to be working good so far

I will have some pics here soon if I can get the camera to work.

Tyler

Sounds high. How tall is the house? I mean from the guage to the highest limb of the heating system. A tall Victorian with a basement boiler and a fully finished (and heated) 3rd floor attic is way different from a ranch. That 30ft water column alone will give you an almost 14psi reading when cold.

I dont think anymore than 10-12 feet above guage.

I think the lowest pressure reading I have seen is 20 pounds. It circulates through the oil burner if it makes any difference but the pressure on the oil boiler was only about 12 or 14 pounds.....

Thanks
Tyler

My set-up is probably like yours. My total head is the same. Initially I had a relatively low mass (7gal) high efficiency oil boiler and all my zones. The pressure didn't move much. However, I added a high mass manual dinosaur when oil got crazy. This beast has over 30gal in it. The problem was that I never changed or added another pressure tank. So when it was cold at around 12psi (and the beast offline) it would expand up to around 15#. With the VanWert at over 180F, the water would expand in to the 20# range.

I ended up letting some water out of the system, and it has helped but I really do need to just add another pressure tank.

Hope it helps.

It could be the expansion tank. Open the drain valve and reduce the pressure and see if it climbs up high again.

Folks

Seems like it must have scooped some more air out of the system after I posted last because I went out and looked and it was down to about 13 pounds with the fire at rest. This was after it cirulated the house awile. I went back in to the oil boiler and had some water leaking through the oil pop off valve. I gave it a quick tug and it squirted out a little bit of water..... and then sealed back up as I hoped it would. This in turn apparently left some more water in on the auto fill which would have been cold water. Now I am back up at about 20 again but it is circulating through the house right now and i want to see if it falls when the fire rests. I hope it does.

Ill post when I find out.... thanks for the help

Tyler

EDIT: The house is up to temp again and the timer will probably kick in a little while again so I may not know for awhile. The fire is at rest right now but Im still sitting on about 20 LBS.

I think the problem is the 520 holds more water than the average newer oil boiler's do, so the "standard" small expansion tank that they stock at all the hardware stores isn't really big enough. My system is all on one floor and the pressure goes from 12psi cold to 25psi hot.

Stokerman:

I have an air scoop on top of the expansion tank..... shouldnt that cut most of the air out of the system without opening the expansion tank valve?

The pressure on the oil boiler is setting right where it should.... between 10 and 12 pounds. The coal boiler guage is at 20 right now with the fire at rest.... but the boiler temp is still pretty high. The house shouldnt call for heat for awhile so I will watch it.

Wonder what caused it to drop down to a lower level earlier?

These things sure do work the mind

If you have an Extrol type of tank, check the pressure. It should be around 13# with the system at zero. If you have a ceiling tank, it could be full of water. It must be open to the system and empty. Your tank could be too small for the system; they are sized by the number of gallons in the system. My two boilers are about 40 gallons of water and I use two #30 Tanks.

What Stoker-man said, and....You put 10-12 pounds in the system. When it heats up the pressure goes up, when it cools, the pressure comes down. As long as it stays below 30, I wouldn't touch a thing. If it hit's 30 water will push out the PRV. This means you need a larger expansion tank. (Or the old style tank is full of water & needs draining).

Stokerman and Freddy-

It went through the night last night and the nearest I can tell it is staying right at 20 pounds. Doesnt seem to drop any when the system isnt running. I think I will do Like Fred said and just let it be. The plumbing man was gonna stop back in Monday night and check things out so Ill see what he says. Im not too swift on that kind of stuff so I will just let well enough alone.... as long as it doesnt approach 30 pounds but I would think that if it wanted to do that it certainly would have by now....?

Thanks for the help
Tyler

CoalJockey wrote:Just lighted the stoker today for the first time and now heating the house and domestic water with it. Keeps the boiler temps set to my aquastat (150-170) and kept fire on this warm day with the timer. Im wondering what the pressure should be. It seems to hover between 20-25 pounds.... is that too much? Seems to me the 1300 in the shop stays between 15-20.

It is common to see a system go over pressure when you first start it, the water is cold and you heat it expands driving the pressure even higher. If you are at 13# and it heats up, 20# is a good target for it. The feed line PRV is a one way valve, it cannot reduce the pressure by bleeding back, you must bleed a little water from the drain to bring the pressure down if you want. In time, it will come down by itself if everything is working properly. If you have closed valves between the two boilers (I assume so, as they show different pressures), just open one and then shut it, the pressure should normalize between the two at about 16-17#.

Coaldsweat:

coaledsweat wrote:The feed line PRV is a one way valve, it cannot reduce the pressure by bleeding back, you must bleed a little water from the drain to bring the pressure down if you want. In time, it will come down by itself if everything is working properly.

By feed line PRV do you mean the line that feeds the boilers constantly with water? Or Auto boiler feed I think is what the plumber called it. Also by bleed a little water from the drain do you mean the drain on the coal boiler? If I do that wont the auto feed just fill it up again?
Its been hovering right around 20 give or take a little.... doesnt show any signs of dropping lately.

Sorry to ask some dumb questions.... I know some of you might roll your eyes at me ( ) But plumbing was never my thing. I set the thing up myself and did all of the wiring myself but I cant even hook up a garden hose without it leaking. Im just trying to get an understanding of how these hot water systems work.

On the bright side of things its roaring away nicely.... beautiful fire and the oil man thinks I switched suppliers!

Thanks
Tyler

The PRV is the pressure relief valve, usually found on the top of the boiler. A pipe should be connected to it and go down to the floor.

The auto-fill valve or pressure reducing valve will fill the boiler when the pressure drops from a leak. If you open the drain at the bottom of the boiler to drain a few ounces of water out and the pressure drops and doesn't go back up, then you're OK.

[quote="CoalJockey"]Stokerman:

I
The pressure on the oil boiler is setting right where it should.... between 10 and 12 pounds. The coal boiler guage is at 20 right now with the fire at rest.... but the boiler temp is still pretty high.
[quote]

I would say one of your guage's is off. One shouldn't read 8-10 psi higher than the other.