PSI required for taller homes?

Steamhead (in transit)

I'd bet that house has higher ceilings than usual. You did the right thing- get enough pressure to fill it to the top. Watch your expansion tank- you may need a bigger one since there's less headroom between fill pressure and blowoff pressure (usually 30 PSI)

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GW

psi

I'm typically working in your average two story home; today I was in this 1920's home with a mostly finished 3rd floor, tall ceilings, etc. The boiler was running at 20 psi, yet I could hear air in the pipes (steel pipes) in the third floor piping distribution (express main to the top, then a header wrapping around the knee-wall of the third floor dropping down to the various supply mains).

If one psi is equal to 2.3' of head, why wouldn't 20 psi get me to the top? When I pushed more pressure into the system and bled some air at the top, one of the mains came back to life.

So, is there a bench mark for pressure, then add for height?


Gary

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Uni R_2

Benchmark

Typically, the objective is to have 5 psi at lowest pressure point in the system which is the top. So measure the difference in height from the highest point down to the pressure gauge in feet, divide by 2.31 and then add 5.

Mike T., Swampeast MO

"Express riser" makes me think an overhead gravity system.

Even by gravity standards these held LOTS of water. Presuming it's been converted to forced flow are you certain there's enough expansion room in the compression tank(s)?

GW

water system

yes, it does look like a steam piping system. This house was built for a very wealthy family back in the 20's.

The expansion tank is a floor sitting model; I did not make mental note of the model. Considering the 2" steel pipes all over the house and the large CI rads, it could stand to use a bigger tank.

Gary

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tim smith

pressure vs elevation

I would bet the gauge is inaccurate. Put your test gauge on and verify accuracy of tridicator. It could exceed 44 ft from gauge but I doubt a 3 story home will. Tim

Al Roethlisberger

My experience....


I have an overhead gravity conversion, house is two stories, but that doesn't tell the whole story.

If you read the standard texts, they will often describe:

10psi typical 1 story house
12psi typical 2 story house
18psi typical 3 story house

etc...

But as some other posts have indicated, this can vary if you have unusually high ceilings, a full basement where the boiler is located(and how deep is it), or in the case of systems like an overhead gravity system... realize that you are really talking about a "3 story house" because all of the riser and distribution piping is in the attic ABOVE the ceiling of the second story.

So, as I mentioned, I have an old overhead gravity system, converted to sealed/circ, and my boiler is in the basement.

I have 10ft ceilings on the first floor, and 9ft on the second, and the basement has an 8ft ceiling if I recall.

When the system is filled to the top, which is about 2 ft above the attic "floor", and add 4-5psi at the top, I get an even 20psi at the tridicator on the boiler. That tridicator is about 2ft off the basement floor.

When I heat the whole system up, and it gets to 180-190F max, I see 23-24PSI with a 30G expansion tank(air cushion, not diaphram).

I have 20 large radiators, and big pipes, so there is a lot of water in the system.

Hope that helps.
Al