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  1. #1
    Join Date
    Dec 2007
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    Heating a house with Tankless Water Heater

    I've been talking to several contractors to research options for replacing a boiler in an old house we just bought and posted a few questions to another thread on this forum.

    However, in the course of my research someone on another discussion forum recommended that instead of putting a lot of money into a new boiler, I'd be better off running my hot water heating system using a tankless hot water heater and then investing the difference into additional insulation for the house.

    I was able to find a couple of websites that show how to configure a tankless hot water heater to supply radiant floor or baseboard heat, but not enough to fill me with confidence.

    Is this something that can be done effectively?

    Does anyone have experience with this setup?

    Can you set this up using old radiators instead of radiant floor or baseboards?

  2. #2
    Join Date
    Jun 2007
    Minneapolis, MN
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    Tankless water heaters are not efficient and not designed or space heating. I have used them on rare occasion but not for entire homes. Find a professional to provide a heatload analysis and install a real boiler, Mod/Con would be best. Save money and buy insulation? Insulate and save money.

    Buy a Mod/Con, save money and use it to buy insulation.

    The Mod/Con is almost always the best option. Those who disagree are misinformed or confused by the high math.


  3. #3
    Join Date
    Jan 2004
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    Quote Originally Posted by BadgerBoiler MN View Post

    The Mod/Con is almost always the best option.


    Almost always, but not always.

    Tankless water heaters are NOT designed for heating houses. They are for heating potable water.

    A mod/con boiler will be your most economical, fuel consumption wise investment, for both house heating and domestic water heating.
    Contractor locator map


    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Jul 2004
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    You get what you pay for. A tankless water heater is designed to raise the temperature of inrushing cold water to a useable domestic water temperature within a matter of seconds. That's a HUGE gas flame. Most tankless's have a gas burner requirement somewhere in the 180,000 Btu input range to do the job. They are NOT designed to have hot water coming into them, which is what you'll get with recirculating heat water. So in that respect alone, they're not designed for heating homes.

    As others have already stated, there a numerous modulating, condensing boilers out there that can be properly sized to heat your home and lower your utility bills. There are also some mod/cons designed to provide both heat and hot water that may be more appealing to you. Sure these boilers are more costly than a tankless water heater but they're more costly because they have a totally different design, which is to heat the home and deal with the hot return water temperatures. You get what you pay for.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

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