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In Floor Heating Set-up

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by lampmfg, Jun 24, 2013.

  1. lampmfg

    lampmfg Member

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    I have a relative who is building a new house in town. Being that's it's right in town he's looking to use in-floor heating (Wirsbo) with a natural gas boiler throughout the entire house (basement, main, 2nd, and garage). It's a 2,000 sq ft two level house ( not counting basement), 1,200 sq ft main level. Any good suggestions on a reasonably priced natural gas boiler?? They currently are looking at a navien that also heats the hot water on demand. Recommendations would be appreciated??

    I think they also said something about a couple of Fujitsu mini-splits to supplement heating, but mainly for cooling in the summer. Any advise?

    Thanks,

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  2. lampmfg

    lampmfg Member

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    This should have probably gone in the gas forum. Sorry
  3. Highbeam

    Highbeam Minister of Fire

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    This is the best forum for it. Gas boilers are way different than anything on the "hearth".
  4. lampmfg

    lampmfg Member

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    Yes,I'm much more familiar with wood burning as well :)
  5. Karl_northwind

    Karl_northwind Burning Hunk

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    we've had good luck with the triangle tube boilers, they're not the cheapest (substantially more than the navian you're looking at, but in the long term....
    they have a model that has internal DHW, but for similar price, you can do a separate tank for better DHW supply if you have the space.
    BTW, I've not used their challenger line, only the prestige and excellence lines.
  6. lampmfg

    lampmfg Member

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    Thanks for the info. Ballpark on price for both models? Looks American made as well?
  7. BoilerMan

    BoilerMan Minister of Fire

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    Viessmann makes world class, as do Triangle Tube. The Navien has had questionable quality and longevity. But that is reflected in the price, just like the Kumma, you get what you pay for. :) Oh, and I'm not a huge fan of combi units (ones that have DHW inside) some type of indirect performs better with less temp fluctuation.

    TS
  8. Karl_northwind

    Karl_northwind Burning Hunk

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    you can find the prices online. the separate DHW tank will give you a much better DHW capability than the combi units, and the better ones are stainless, and all will outlast a gas fired water heater. I Don't know the country of origin of the boiler, nor its components.
  9. Bob Rohr

    Bob Rohr Minister of Fire

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    It really depends on how much DHW you want. I have two Combi boilers running at my place. At the in-laws, a Laars (Baxi) that is 4 years old. I just installed a Lochinvar Cadet with DHW in my home. With 50• incoming well water both provide plenty of DHW for showers, tub filling etc.

    If you need a large dump capacity to provide for multiple draws at the same time, a tank style is a better choice.

    It's rare to see a tank style DHW heater in homes or flats in Europe. Space limitations, as well as fuel cost drive owners to tankless style, or boilers with DHW heat exchangers.

    Tankless or HX style DHW units should be installed with some isolation valves to flush and de-lime them if and when needed.

    Even the best insulated indirect tanks loose energy, more then the 1/2 degree per hour they advertize. Unless they are installed in a very warm space.

    There is a good application for all types. Tankless or boiler with DHW work nicely with solar pre-heat.
  10. heaterman

    heaterman Minister of Fire

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    Any tankless water heater type product is a poor choice for heating use. They are set up to operate under an entirely different set of circumstances and perform very poorly when used for heating. Believe me I've tried this because the price is so tempting.

    The biggest issue is that of the supply/return temp difference. Tankless units are set up to run at 60-100* temp differential from incoming to outgoing. Put one in a system where the differential is only 10-20 degrees and they cannot handle it. They will fault out in high temp limit and the burner will never ever ramp up to maximum output.

    As an example, a heating boiler will usually have a heating surface/btu ratio in the range of 1 sq ft / 8-12,000 btu. A tankless with a max firing rate of 200,000 has a heat exchanger about the size of a quart jar.
  11. BoilerMan

    BoilerMan Minister of Fire

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    He is talking about a combi unit, not using a tankless to heat a slab.

    TS
  12. Karl_northwind

    Karl_northwind Burning Hunk

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    Agree with Heaterman, the efficiency numbers and hydraulic characteristics of on demand water heaters are not aligned with the needs of space heating. the only thing they have going for them is that they're cheap.

    in most cases, if space allows, I spec a separate boiler and indirect tank. everything's easier to work on, and if one part fails, a replacement of any brand is readily available and easy to retrofit in. like any other plumbing project, code will dictate what the hot water supply needs to be able to meet. in the case of a 75 gal whirlpool tub, an indirect fired combi unit will take a long time to fill that tub at 3 gpm. a 50 gallon tank will fill it quickly, with a happy customer soaking in it.

    I've not spent any time in europe (this fall hopefully, visiting boiler manufacturers) but I'm guessing that big whirlpool tubs are not nearly as common there as they are here. a flat with 1 shower isn't the same as a 4 bedroom house, and more importantly, the people in said domiciles are of different flavors.

    karl
  13. lampmfg

    lampmfg Member

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    I appreciate the feedback.

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