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Pickup Factor Help, Please

I've measured and multiplied and arrived at 470.7 sq ft of sometimes-used radiation. If the radiators don't lie, I have single pipe steam.

I read in We Got Steam Heat that missing radiators also need to accounted for, and that a decision needs to be made re what multiple to use for pickup factor.

It is very clear that this house was built (1926) when boiler fuel costs were NO concern at all! One missing radiator was in my small front vestibule, above my root cellar. It's cold there but that's fine. The other was in my kitchen and was remodeled away before I got this house 37 years ago. It's not missed at all.

The third radiator I excluded from my calculations is in my garage-- as in, that area with the huge not-at-all-airtight overhead door! In Michigan! Whatever were those Dead Men thinking? The radiator is still there, but definitely has not been turned on in the 37 years I've been here. So I treated it like a missing radiator-- is that okay?

This house is strangely configured, and I'm thinking that should effect the factor I should use as well. The basement is an L-shape, or would be if the L had even length arms. The first floor living area is that same L, and the garage is the piece missing to make it a near-perfect square. Garage walls are all concrete block, and there is no entry into the house.

The second floor is a square, with a hallway, 4 bedrooms, 2 Jack & Jill bathrooms and a dressing room. One of those bedrooms is above the unheated garage space so it tends to be chilly but that is really okay.

Third floor is attic space, plus one bedroom and one bath.

So that is a lot of piping to all those 18 radiator connections, with the extra cold exposure from the unheated garage space, hence I'm wondering if 1.5 is even a high enough factor.

I'll be replacing a cracked 210,000 Burnham Independence (IN7?) with either another Burnham or a McLean of to-be-determined size.


  • Jamie Hall
    Jamie Hall Member Posts: 22,897
    The 1.5 should be fine...

    provided -- and this is really important when you have longish mains, or mains in unheated areas -- the mains are insulated.  I'd use a 1" fiber glass; it's available in a fairly easy to install snap-on form.  What the pickup factor is for is to get the mains warm -- not to keep them warm if they aren't insulated

    You mentioned at the end of your other thread -- on that radiator -- that there were three mains tied into the boiler.  That shouldn't be a real problem, but if you were to post a picture or two or three of how things are tied together now you just might get some suggestions..
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • vaporvac
    vaporvac Member Posts: 1,520
    Insulate main in garage...

    Hi, I also have a rad in my garage. The main leading to it is uninsulated and I believe they depended on the rad to heat the mains somehow. So I would definitely insulate that main if it isn't already. I never noticed mine until this year and that explains why the two rads coming off AFTER the garage rarely heat up.

    You should have plenty with 11/2 pick-up factor. Just remember when looking at boiler ratings that the pick-up factor is ALREADY included. Just look at the EDR for which it's rated. if you have questions at that point feel free to ask them. I've been there and it's overwhelming, unless you bite off a chunk at a time, as you are doing. Colleen
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Steamhead
    Steamhead Member Posts: 16,718
    Those garage radiators

    were installed because there was no automotive antifreeze in those days. So you either heated the garage, or drained all the water out of the engine block and radiator when you put the car away. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Overwhelmed_2
    Overwhelmed_2 Member Posts: 18
    edited January 2014
    Factor Already Included? WHAT?


    What? Already included? What do you mean? How can it possibly be included if one needs to decide WHICH of 1.33 or 1.5 to use?

    Am I doing this right?

    Total sq ft for radiators in use = 470.7 x steam conversion factor of 240 = 112,968. And that's it? I only need a 113,000 BTU boiler?

    I thought I ALSO had to then multiply by the appropriate pickup factor of 1.5 (assuming I can add insulation to pipes in unheated areas especially) which would bring me to 169,452. No?

    That would be a 172,000 I guess, to replace the 210,000 I have now. Even that does not seem right somehow-- I'm wondering if the prior size specifier (my late husband) was upsizing to account for Jamie's keep-them-warm caution.

    Now I'm really afraid I'll end up ordering the wrong size. Where am I off here?

    Steamhead: Really? So everyone living in cold climates (including Henry Ford's Michigan) HAD to have a heated garage back then? Wow. Never thought of that!
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    edited January 2014
    Sizing a boiler

    What Vaporvac refers to is the boiler raising in square feet of steam. When you look at the choice of boilers, and go further into the specifications, there will be a steam square feet column. You want to look at that for your match, and not any multiplier for BTU's if you can avoid it. Try to match up as closely as possible even if you are a tad under. I think in the atmospherics, you are close to a Peerless 63-05 (go to their website and look for steam square feet), and that has the pickup included.--NBC

    Maybe also a 63-04
  • vaporvac
    vaporvac Member Posts: 1,520
    edited January 2014
    Sorry for the confusion...

    This is what happen when I try to help. You are figuring it right. Nicholas explained what I meant better; it's only when you look at the ratings for the boilers that you need to be careful. Some people accidentally end up with a boiler way

    too large and that can lead to short-cycling which means more money to

    heat your house.

    If you run it by the folks here, they can double-check and then you'll know for sure. That's what I did and hopefully, I'll have heat tomorrow.

    Concerning your sizing, don't forget that your current boiler may be less efficient so a ;newer one doesn't have to be as large.  Colleen
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • vaporvac
    vaporvac Member Posts: 1,520
    Memory jog...

    You brought back so many memories of stories about my Grammy putting the car up for the winter when my Dad was young. I always wondered why, but I guess that was at least one of the reasons.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF