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Best way to do floor warming.

Don Walsh
Don Walsh Member Posts: 131
I am being approached more and more often for floor warming applications. I have found that cost is a serious impediment to the advance of this application in my area. I am looking for information from all of you as to how you best install floor warming systems. Are you using water heaters? What temperatures do you recommend? What spacing and mounting applications do you use? What type and how much insulation are you using, and what have you found to be the best control system? I need to find a cost effective method of installing these systems. Your input will be greatly appreciated. Grumpy

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Comments

  • hr
    hr Member Posts: 6,106
    What size areas?

    There are some elecrtic mat systems that can be installed under the sub floor. I think Watts Radiant has some with UL approval.

    For areas of 200 square feet or less electric in the tile set or under the floor makes sense, installed cost wise.

    I still do mostly hydronic with a 2 or 6 gallon electric water heater with pex and or plates.

    Often times a suspended tube with a WH running 120- 130° is plenty. I use R-19 fiberglass batts below.

    The tekmar 500 series dual stats are a favorite, use it with the floor sensor option.

    Less expensive would be a simple setpoint control with a floor sensor, but it will take more owner adjusting.

    I can generally do a kitchen or master bath, 1 zone system, in a good day, using a small electric tank. probably still in the 2 grand price range, depending on your hourly rate.

    If the home has an existing boiler you can do a radiant loop from it. I've found it takes more time, and often cost to pipe in a mixdown loop, than a self standing electric hydronic system, however.

    I have also used the Danfoss HX panels connected to an exisiting water heater. Takes all the plumbing parts and labor out of the equasion, just tube and 4 pipe connections.

    Plenty of options.

    hot rod

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  • Grumpy
    Grumpy Member Posts: 26


    Thanks for responding Hot Rod. Do you usually use 1/2" or 3/8" tubing, and what do you feel is the minimum BTU per sq. foot needed for floor warming when it is hard surface materials only, ie: ceramic, marble, or slate flooring materials?
  • Grumpy
    Grumpy Member Posts: 26


    The cost of electric precludes the use of electic mats in our area. But thanks for the URL anyway, all information adds to the menu of options for my customers! Grumpy
  • hr
    hr Member Posts: 6,106
    I like 3/8

    with loops under 200 foot. I like Wirsbo Hepex for flexability

    For warming 5- 15 BTU/ ft. Wirsbo tables show suspended tube at around 16 BTU/ ft at 130 with R-.5 covering.

    You're bumping up against 20 BTU/ ft with transfer plates at 130.


    Do a loss calc for the room to be sure. Generally I'll close any FA vents in a master bath and let the radiant handle the entire load. Remember to open them for cooling season :)

    See ME' post about the 2 btu foe each degree of difference between air temperature and floor surface. I run mine at 78° maybe a bit more in real cold weather.

    By far the nicest addition to any home is a master bath radiant retro. Once you get the method down they are a money maker, slam dunk one dayers.

    Rarely get a price complaint once folks start talking to friends and neighbors that have added this system. The nicest 2- 2500 investment a homeowner can invest. Get a couple going, word will spread quickly.

    Now go sell 'em!

    hot rod

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  • Pat_12
    Pat_12 Member Posts: 27


    Hot Rod,
    I love the information you supplied on this post. Who is the manufacturer of the manifold you show in your pictures? Great idea using the small water heater. Thanks for all your help.
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