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Is the cost of a mod-con worth it on hi-temp baseboard?

Saggs
Saggs Member Posts: 174
I keep going back and forth on this issue.  I see a lot of GB142's and the like being installed in old oil heated homes with traditional fin tube baseboard and wonder if the savings is really there?  These homes need 160-180 deg water to heat properly and you're out of the condensing range for these guys where the real savings kicks in.  I've installed a few cast iron gas units instead which were significantly cheaper than a 142 and are still saving the folks money with an ODR control as well.

Any thoughts on this, I often think they're not all that they're cracked up to be.  With radiant or over sized BB then yes, they shine.

Thanks, George

Comments

  • Tom_133
    Tom_133 Member Posts: 773
    Same page

    Saggs



    I hear what you are saying, my question is always: Does the modulation save enough to cover the sometimes frequent and expensive service calls or yearly maintenance?



    I was curious if someone has crunched the numbers of fuel consumption of 87% bullet proof cast boiler and a 95% wall hung mod con on baseboard for a heating season? Factoring in upfront costs, LP or Nat difference (price, BTU), additional piping for modcons, and all the miscellaneous that go with them.



    My opinion is modulation when sized right for the load should give you the payback even with high temp baseboard.



    Hopefully someone who can give real world numbers chimes in as well.
    Tom
    Montpelier Vt
  • JStar
    JStar Member Posts: 2,752
    Mod-Con

    Point #1. First time I ever saw 99.5% Efficiency on my analyzer was on one of our Triangle Tube boilers installed in a fin-tube baseboard system, operating during the summer.



    Point #2. We run more service calls for cast--iron boilers than we do for mod-cons. Higher service/maintenance for mod-cons is a myth.
  • icesailor
    icesailor Member Posts: 7,265
    Efficiencies:

    99.5% combustion efficiency is not the same as 99.5% operating efficiency. And there are far too many variables to accurately compare apples and oranges.

    How do they come up with these magic numbers?

    I suggest that if and when you get into the back rooms of your computer, and see the machine code that runs the programs to make these empirical prognostications, you will see smiling faces and signs of the devil. Devil's make that stuff up.

    My short bus math goes like this.

    If we call a BTU, one penny ($.01), we have a constant to use. If there are 91,000 Btu's in a gallon of Propane/LPG, and we put 91,000 pennies in a gallon bucket, and then if #2 fuel oil is 140,000 BUT's per gallon/pennies, in a gallon bucket, for whatever you pay for the fuel, which bucket do you want?

    If I am walking down the street and I have only one penny coin  to my name, I'm worth a penny. If I spot another penny in the street and I pick it up, I've doubled my worth. I have two cents to my name. If I find another penny, my wealth has increased by one third. I'm worth three cents ($.03). If I had a dollar bill in my pocket, and I found a dime on the sidewalk, I'm worth far more than I was when I found two pennies.

    As far as the percentages goes, on the Massachusetts Master Plumber test, they always had a variant of the question of:

    If you bought a widget for $100.00 and you wanted to mark it up by 20%, how much would you  mark it up and sell it for?

    If you said $120.00, you are WRONG and would have been marked down accordingly.

    The correct answer is $125.00 because if you deduct 20% from &120.00, you get $96.00. If you deduct 20% from $125.00, you get $100.00. Fun with numbers because all math questions can be proven with the opposite operation.

    I've seen people complain about the cost of heating their house. Do a complete remodel, new windows, insulation, and new latest boiler that was running at 82% for a new boiler that is running at 90%. They rave about how much they save. Before they changed the boiler, they should have done a comparison. Then taken the cost of the new boiler etc and cost it out over the projected time chosen.

    Good advertising.
  • JStar
    JStar Member Posts: 2,752
    Eff

    I understand the difference between combustion and system efficiency, but you can't have a total system efficiency that is any greater than your starting point (combustion). On the other end, a more efficient system, and a more efficient envelope will go much further than the difference between 82 and 96% combustion efficiency.
  • SWEI
    SWEI Member Posts: 7,356
    Condensing and baseboard

    really do work just fine together http://www.fcxalaska.com/PDFs/AshraeCondensingTechnology.pdf