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# 28 inches.

Member Posts: 11,966
When measuring to see if you have 28 inches from your NWL to the lowest steam carrying pipe I assume dry returns also count?

My issue is if I want to go with an IN5 it appears I might only have 27 inches to the end of one of my dry returns.  The steam main is much higher obviously.

Will this cause a problem?

I'm having trouble getting a perfect measurment as the boiler is on a concrete slab while the dry return is over dirt. I may need to make a water level to be sure.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

• Member Posts: 14,831
Should be OK

there was a bit of extra headroom in the 28-inch "A" dimension.
All Steamed Up, Inc.
Steam, Vapor & Hot-Water Heating Specialists
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• Member Posts: 2,752
Numbers.

Your A Dimension technically only needs to be high enough to match the steam's pressure loss in the main, plus a little extra. If the boiler runs at 2 psi, and the steam loses 1/2 psi at the end of its run, you would need an additional 1/2 psi of pressure to push the condensate back to the boiler. 1/2 psi = 14 inches. But just adding another 1/2 psi would only equalize the supply and return, so to make sure that the condensate really gets pushed back into the boiler, we raise the A Dimension to 28. 28 inches = 1 psi. So now the return has 1/2 psi more pressure than the boiler (1-1/2 plus 1).

In other words....27 inches is fine. It equals something like 0.96 psi.
• Member Posts: 11,966
Ah

So theoretically something like say, 20 inches should work under most conditions?

I'm curious, is there a way to calculate the pressure drop in a steam main?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
• Member Posts: 2,752
edited August 2011
Ummm.

A pressure gauge? I've never had the need to do it. If I had steam in my house, I would put a gauge at my main vent location just to actually see what it is. Supposedly, all/most/some/any? stream system should be sized for a 1/2 psi drop on the main. I know there's a way to calculate it but I'm sure it's in a book or chart somewhere that I just can't picture right now.
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