Main Air Vent

Chris Mills

I am brand-new to boilers and steam heat. These will be two VERY basic questions; I've read "We got Steam Heat" and "The Lost Art . . ." and am trying to track down water hammer on start-up, and REALLY high fuel bills.

Q1: The return lines all dump into a sump return pump which of course goes back to the boiler. I would assume that the presence of a sump return obviates the need for a main air vent, since the "system" is now open to air. True?

Q2: Dan makes repeated reference to the required (low low low) pressure needed to "push" the steam around; we are heating a 9,000 (!) square foot house with poorly-to-not-insulated feed pipes coming from a 15 psi max-rated oil-fired 2263 sq ft 543K BTU oil-fired relatively new boiler which has been completely overhauled. The working pressure had been set at about 7 psi and we are in the process of replacing the broken pressuretrol to see what happens if the pressure is reduced to, say, 0.5 to 2 psi. Will that be enough pressure, assuming that the initial pipes were big enough for the long-runs associated with this monstrosity of a 50 year-old house?

Thanks for your help.

cam

DanHolohan

Q1:

True, but this assumes that all the pipes slope into the feed-pump's receiver and air can get out. Ask yourself, "If I were air, could I get out?"

Q2: Yes, you can run this on very low pressure IF the air can get out, the pipes are insulated, the quality of the steam is good, the firing rate is proper and so on. The stuff that's in the books. Thanks for reading!

Steamhead

If the pressure is low enough

you may be able to do away with the pump. In a normal residential steam installation, you should be able to run at no more than 2 pounds. If it's a Vapor system, it might only need 8 ounces! Then you wouldn't need a pump to overcome the boiler's pressure.

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Boiler Guy

Dan

I can't thank you enough for insisting I buy the bright orange CCW screwdriver. I am having a whale of a time unlearning all of the stuff I was ever lead to believe about the "black magic" of steam. I have actually made a couple of engineering converts in the process. BTW what happened to your companion book to Lost Art?

DanHolohan

Thanks

The Companion is out of print.