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  1. #1
    Join Date
    Aug 2009
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    Default radient floor heat and tankless water heater

    My wife and I will soon be building a new home in the mountains of Utah. Ultimately we'll retire there and live full time but for now we'll be there part time only and the home will be empty for weeks at a time. I'm putting in tankless water heaters so I don't have to heat water when I'm not there. We would really like radient hot water floor heat but how does that work with the tankless water heaters and not being there all the time? Also, our builder tells me that we'll need a forced air system anyway since we'll need AC for some summer days. We don't want to pay for 2 heating systems. Any ideas? Are we stuck with forced air? The tankless water heaters is the #1 priority, or so we think now. Please help.

  2. #2
    Join Date
    Jul 2008
    Location
    San Francisco , Ca
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    43

    Default Re: radient floor heat and tankless water heater

    you need to consult a local plumbing heating contractor.. i will tell you though tankless is a bad option for domestic and radiant.. i'd say a mod con bolier with a indirect tank with air handler..

  3. #3
    Join Date
    Oct 2008
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    116

    Default Re: radient floor heat and tankless water heater

    If I had a house I was going to be absent from for long periods, I would install forced hot air. This not only gives you the chance to easily add A/C, but also you don't have freeze issues in the winter if you lose power for long periods of time.

    As far as hot water goes, I would get what is most easily drainable, for the same reasons as above.

    GOOD LUCK!

  4. #4
    Join Date
    Feb 2008
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    175

    Default Re: radient floor heat and tankless water heater

    I would agree with direnek1 and Cougars1996.

    Google "tankless water heater for radiant heat" (with the quotes) to get additional opinions on flow rates and delta T's.
    Last edited by Dobbs; 08-16-2009 at 06:49 PM.

  5. #5
    Join Date
    Jun 2008
    Location
    Central Wisconsin
    Posts
    12

    Default Re: radient floor heat and tankless water heater

    I built a new house last fall and spent some time looking at the same options you are considering. Our primary plan was to use a Geothermal system for heat & hot water, but expense vs. budget eliminated the Geo system for now. We currently use an LP gas FA furnace w/A/C for upstairs and Radiant heat for the walkout basement.
    You builder is right in that you will need a ducted air system in order to have A/C. This can be done either thru a regular forced air system or a heat-pump/fan system.
    Tankless water heaters are very efficient depending on how much demand your family has for hot water. These are great if you plan to be gone for long stretches of time as you won't be using power to keep hot water in your absense. They can be heated via electric or gas (LP or Natural) depending on what is available in your area. They cost quite a bit more intially, but if you plan that into your construction loan it easy to absorb that cost.
    The Radiant heat is Great! There are several different systems for heating for these. You can use Geothermal, Electric boilers, Outdoor wood furnaces, or LP (& natural) gas boilers.
    Outdoor wood furnaces require a fairly constant supply of wood, and you have to be home to feed them. Electric boilers can be expensive, however your Electric Utility Co. may have programs available to set you up with a separate meter, or time of day programming that offers much lower rates for items such as these boilers.
    Based on all this info, you could easily set up both your tankless water, and heating system on either electric or LP gas systems. Personally, I still plan to swap out to a Geothermal system in the next 2 years once my 2 oldest kids are out of college and the related expenses go away. Now that the Gov't has set up some great Tax incentives for these systems, this is the time to do it if it fits your budget.
    Also, Check into some of the other new homes being built in your area & see what others are doing or have recently done. Ask them how well these systems are working for them.
    And as djrenek1 suggested, contact your local plumbing/heating contractors. Ask them what combinations work best with your climate & needs.
    JP

  6. #6
    Join Date
    Jul 2008
    Location
    San Francisco , Ca
    Posts
    43

    Default Re: radient floor heat and tankless water heater

    also look into combi style boilers basically a boiler that runs heating zones on one side and a tankless exchanger with buffer tank built in on the other side.

  7. #7
    Join Date
    Aug 2009
    Posts
    2

    Default Re: radient floor heat and tankless water heater

    Quote Originally Posted by inisfre View Post
    My wife and I will soon be building a new home in the mountains of Utah. Ultimately we'll retire there and live full time but for now we'll be there part time only and the home will be empty for weeks at a time. I'm putting in tankless water heaters so I don't have to heat water when I'm not there. We would really like radient hot water floor heat but how does that work with the tankless water heaters and not being there all the time? Also, our builder tells me that we'll need a forced air system anyway since we'll need AC for some summer days. We don't want to pay for 2 heating systems. Any ideas? Are we stuck with forced air? The tankless water heaters is the #1 priority, or so we think now. Please help.
    Thanks to one and all who replied. Very helpful!

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