Click here to Find a Contractor in your area.
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/.

Weil McClain sizing

Brad White_9
Brad White_9 Member Posts: 2,440
<i>"I'm good with spreadsheets. I'm located just northeast of Detroit."</i>

Indeed, the facility of folks living in the northeast quadrant of Detroit to use spreadsheets is becoming well-known. :)


St. Clair shores perhaps?

Anyway... I am glad you see that this is entirely workable... insulate your piping, vent your mains and radiators, add TRV's... If your Steam guy is not one of us, maybe he should be?

Comments

  • Tom Woodman
    Tom Woodman Member Posts: 15
    Weil McClain sizing

    The Weil Mclain ratings chart has a column for DOE Heating Capacity BTU/Hr and another column for Net I-B-R Ratings (Steam BTU/hr). Which column do I use to figure out which size I need?

    I have a two pipe steam system and my heat loss calculation was 66,000 BTUH (three story 1750 sq ft home). I'm planning to oversize by at least 25% to 82500 mostly because the boiler I'm replacing is 150,000 BTUH and I'm paranoid about reducing the size below about 100,000 BTUH.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Steam versus Water

    There are a good number of threads on this very subject, Tom.

    For steam you size the boiler based on it's output in EDR. If you use the I=B=R steam rating, that has 33% built in for piping and pickup from a cold start. You can eat into that a bit if your piping is well insulated. What is your connected radiation square footage in EDR?

    The other side of the coin is, you may have too much radiation hence require a bigger boiler (regardless of your heat loss). If you have insulated and added new windows and sealed the place up tight, you may well have too much radiation.

    With a hot water system, too much radiation is good- it translates into cooler water temperatures more often. Steam is essentially fixed in temperature between 212F and 215F so having more radiation than you need is not so beneficial.

    Measure your radiators, buy Dan's EDR book or seek other resources and go by those numbers. No shortcuts, sorry!

    But it is GOOD that you have a heat loss calculation.

    Brad
  • Tom Woodman
    Tom Woodman Member Posts: 15
    ugh!

    We probably have WAY too much radiation. Can't I just turn them down with the valves on the radiator?

    Sounds like the heat loss calculation really doesn't do me any good. I don't even know what EDR means. Plus, I can't imagine what it would cost me to put in all new radiators!

    I guess I need to just replace the old steamer with another one the same size. Right now we have NO HEAT. My wife is going to kill me if I don't get moving on this.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Breathe, Tom, Breathe......

    Not the worst situation to find yourself in! Where are you located?

    The heat loss calculation just tells you where you should be and is a good benchmark.

    "EDR" is "Equivalent Direct Radiation", a term of measure of the surface areas including all nooks and crannies, of a cast iron radiator. The numbers are expressed in square feet.

    Each "square foot EDR" at steam temperatures and in a 70 degree room is worth 240 BTU's per hour. Thus a 60 SF EDR radiator will emit 14,400 BTUH (enough to heat a well insulated principality in a mild climate).
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Breathe, Tom, Breathe......

    Not the worst situation to find yourself in! Where are you located?

    The heat loss calculation just tells you where you should be and is a good benchmark.

    "EDR" is "Equivalent Direct Radiation", a term of measure of the surface areas including all nooks and crannies, of a cast iron radiator. The numbers are expressed in square feet.

    Each "square foot EDR" at steam temperatures and in a 70 degree room is worth 240 BTU's per hour. Thus a 60 SF EDR radiator will emit 14,400 BTUH (enough to heat a well insulated principality in a mild climate).

    Take a survey of each radiator, noting the number of sections, number of tubes per section, the distance/spacing center to center of the sections and the type (small tube, column, oval). The Burnham web site has a PDF format of their "Heating Helper" which has a good variety of obsolete radiators. These tables express the outcome in SF EDR per section. A short spreadsheet will speed things up.

    Get going and see what you come up with.

  • Steve L.
    Steve L. Member Posts: 35


    You must size a steam boiler based on what is called the "connected load". In a steam system you must be able to heat all of the cold piping and radiators througout the system. So even if you replaced windows, insulated etc... The piping and radiators still require the same amount of steam to heat up.
    So please measure your radiaton and piping and size accourdingly. There are many other things to consider is sizing a new steam boiler. Dan's book has lots of info that will help you with this.
  • Tom Woodman
    Tom Woodman Member Posts: 15
    I can do it!

    OK, Brad (and Steve)

    Thanks for talking me down. I can do this. I'm going to go start measuring right now. I'm good with spreadsheets. I'm located just northeast of Detroit.

    I'm going to get a bunch of TRVs, too. I have one of them already, I just didn't realize it. I saw another one of your posts that pretty clearly gave all of the steps.

    Plus, just now, I got a call from a steam guy that seems to understand all of the things I've been questioning on this site over the last week or so. I'm going to meet with him.

    But, at this point, I'm definitely doing it myself unless he is clearly as knowledgeable as you are!
  • Steve L.
    Steve L. Member Posts: 35


    FYI when you size the radiators you must count the number of sections. And note the number of colums. There is also a chapter on Rad sizing in Dan's book.

    Good luck.

    Steve L.
  • Mitch_6
    Mitch_6 Member Posts: 549
    Not to be wise

    Just curious, now that Tom can size a boiler who is doing the install.

    Mitch S.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
This discussion has been closed.