Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
If our community has helped you, please consider making a contribution to support this website. Thanks!

28 inches.

Options
ChrisJ
ChrisJ Member Posts: 17,070
in Strictly Steam
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 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

Comments

  • Steamhead
    Steamhead Member Posts: 18,205
    Should be OK

    there was a bit of extra headroom in the 28-inch "A" dimension.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • JStar
    JStar 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.
  • ChrisJ
    ChrisJ Member Posts: 17,070
    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 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • JStar
    JStar 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.
This discussion has been closed.

Categories