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Boiler sizing question

Sean_11
Sean_11 Member Posts: 21
in THE MAIN WALL
Home has 195EDR of radiation. Main header is currently uninsulated, but am going to do that. Rest of pipe insulation is intact, and no missing rads or capped risers. Tossed up between WM EG-30 (75000BTU input)and EG-35(100000BTU input), which are rated for 192 and 254EDR respectively. I'm leaning toward 30. Is this a good call?
Will also be using it for IWH. If I ever want to add baseboard loop to small basement (haven't done heat loss, but it's a small attached home), will EG30 be undersized, or is there enough hot water overhead for both IWH and baseboard?

PS - changed out Dole 1933 vent that was on main to 2 Gorton #1 vents, difference is dramatic.

Best regards,

Sean

Comments

  • JoeV
    JoeV Member Posts: 62
    I'm interested too.

    A professional aquaintence who maintains my plant's HVACs is interested in replacing my residential steam boiler. He hasn't installed a boiler in twenty years, when he apprenticed under someone else. Around here it's slim pickins for boiler installers so I felt inclined to engage him.


    The calculated DOE required is 85MBH. The boiler I desire has a DOE of 87MBH but the boiler he desires has a DOE of 115 MBH. "Gotta have a fudge factor" he says. I tell him we do have a fudge factor in the pick up of 1.55 and plus the boiler is a hair larger than needed.

    He says if he undersizes it I'll be miserable and mad but I feel if he oversizes it i'll be miserable and mad anyway.

    I'm inclined to pass on his service unless someone can convince me he's right. Any answer would beappreciated.

    Sorry to ride on your post Sean, but it was relevant to me too.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,488


    I would tend to opt for the two smaller choices. As mentioned the pick-up factor for steam is 1.33
  • Sean_11
    Sean_11 Member Posts: 21


    Thanks for your reply Ed. I've read a lot of the resources on this site, along with my copy of "Lost Art" to get a better understanding of steam boiler sizing, but just wanted to make sure that sizing the boiler for its steam load would still allow it to handle those other loads. The baseboard heating loop is only a possibility, as I want to see how comfortable basement will be with main insulated, but I definitely will have boiler hooked up to IWH.

    Forgot to mention, that bedrooms now have TRVs on them, although I know I still have to fill the rads with steam before TRVs throttle down.

    Best regards,


    Sean
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