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condensing boiler

John_82
John_82 Member Posts: 63
Is it worth it installing a condensing boiler on a retro fit job w/ all baseboard? I ran into a guy who was thinking about it. I can't think the unit would be in condensing often (if ever) based on the original system design being based on 180 degrees supply w/ a 20 degree delta t. I could justify such a boiler being used with a radiant system operating at low temps, then the boiler would be in condensing and economy would be maximized. What does the group think?

Comments

  • Ken_8
    Ken_8 Member Posts: 1,640
    It's worth it!

    Since the full tilt boogie output of the system will only be required on a degree design day, which may happen three or four times a year, the boiler will condense at max efficiency most of the time.

    If they need a new boiler, now's the time to install a condensing model.

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  • Steve Rockwell_3
    Steve Rockwell_3 Member Posts: 18
    Results Speak For Themselves

    I am a homeowner, and had an Ultra installed in my home, which is roughly 80% baseboard, 20% standing iron and 0% radiant in November of 2004. I also had TRV's installed on the CI rads.

    In the five months since installation, with heating degree days about 5% colder than last year here in Michigan during that period, my gas consumption (therms) has decreased just over 38%.

    With outdoor reset, constant circulation, TRV's, and the modulating boiler, the house has never been more comfortable. By the way, despite temps as cold as -5* this winter, my boiler never needed to go over 165* to keep the house warm. With temps in the 40's over the weekend, it was running at about 115-120*.

    With those results, I for one am sold on condensing boilers with baseboard.
  • LEAD PIPE
    LEAD PIPE Member Posts: 199
    I too have an ultra & base board

    I love the Ultra I also see a savings between 35& 40% depending on the temps. that month. The out door reset comes with the boiler and it allows you to make many adjustments to gear the system for your home.
  • Kritz_3
    Kritz_3 Member Posts: 85
    Condensing

    I would say that if you want to save some cash in the long run go for it! The savings will be there, not as fast as if you were running lo temps for radiant. But you will be running longer lower, plus if you do retrofit to radiant you have the heart of the system in place. Jonh do happen to work @ CCNY in Harlem?

    Good luck , Steve
  • Kritz_3
    Kritz_3 Member Posts: 85
    Condensing

    I would say that if you want to save some cash in the long run go for it! The savings will be there, not as fast as if you were running lo temps for radiant. But you will be running longer lower, plus if you do retrofit to radiant you have the heart of the system in place. Jonh do happen to work @ CCNY in Harlem?

    Good luck , Steve
  • Darin Cook_3
    Darin Cook_3 Member Posts: 389
    We had a customer with identical results

    They had a reduction of 38% of therm usage. All baseboard in the home with a indirect water heater. Eight people living in the home. That is a huge immediate savings. It will not take long for a payback to occur. Condensing, modulating boilers fit every application. The proof is out there in reduced fuel usage=money in your pocket. Natural gas or propane it does not matter you will save money. You will not be sorry if you go with a condensing boiler.









    Darin
  • Dave Yates (PAH)
    Dave Yates (PAH) Member Posts: 2,162
    similar results here

    On a wide variety of systems. BB, cast iron and a hydro-air system we installed utilizing a six-pass coil in order to ensure the boiler will see condensing temps due to low return-water temps.

    Our customers are reporting anywhere from 70% to 30% reduction in fuel usage.

    Here's an excellent article on a recent study: http://www.contractormag.com/articles/column.cfm?columnid=388

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  • Simply Rad_2
    Simply Rad_2 Member Posts: 171
    Six pass coil?

    Dave
    I was wondering if you could expalin the six pass coil theory. I do not understand, but I am very interested. I have always installed condesing boilers with low temp radiant and not with high temp baseboard. WIth my Bacharach analyzer at supply temp of around 100 degrees condensing units are around 95+% efficient and at 160 degrees the unit is around 86% which is equivalant to a cast iron.
    Thanks Jeffrey
  • Simply Rad_2
    Simply Rad_2 Member Posts: 171
    Six pass coil?

    Dave
    I was wondering if you could expalin the six pass coil theory. I do not understand, but I am very interested. I have always installed condesing boilers with low temp radiant and not with high temp baseboard. WIth my Bacharach analyzer at supply temp of around 100 degrees condensing units are around 95+% efficient and at 160 degrees the unit is around 86% which is equivalant to a cast iron.
    Thanks Jeffrey
  • joel_25
    joel_25 Member Posts: 4
    analyze this!

    Your analyzer is not telling the whole story because your flue efficency is not actual efficency. Your forgetting the higher standby losses of a large (relativly)cast boiler and much more. Take a Vitodens since it MODULATES the burner to meet the load the boiler is much more appropriatly sized to meet the load of individual zones. We all know how bad oversizing is , but your analyzer can't see it. If the Vitodens is running hot at 20k BTU on a 20K BTU zone and at 86% eff is it not more efficent than a cast 120k boiler that is banging on and off for that 20k BTU zone , even if the flue gas of the cast boiler is 86% ?
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Yup...

    What Joel said. Ignore the man behind the curtain!!

    On my Li'l Munchkin, where I have all the flow meters and thermistors, when I was seeing 99.8% THERMALLY efficient, my combustion analizer was telling me that it was only 92% combustion efficient.

    Take the CO course the next time its in Denver with Jim Davis, and he'll tell you what features you should pay attention to and which ones to ignore, and the BIGGEST one to ignore is the combustion efficiency. There are no less than a hundred ways to get to the same number. Which one is correct...

    ME
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