Converting Watts to BTU's

Discussion in 'HVAC Heating & Cooling' started by johnfrwhipple, Jan 3, 2010.

  1. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  2. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    North Vancouver, BC
    Converting electric heat (watts) to BTU's / hour

    Thanks that is what I meant BTU / HR

    Your numbers work out with my first attempt.

    I found another website describing the heat output of cable heat electric flooring with a 3" standard spacing to be 34 BTU'S per square foot.

    http://www.warmyourfloor.com/warmwireinstallation-1.aspx

    Rather than trusting this site the cable heat kit I'm going to use is from Warm Tiles (DFT 2065 60-70 sq feet 3.3 Amps).

    Can you covert Amps to Btu's per hour? Just found this thread (http://forum.onlineconversion.com/showthread.php?t=421) online...

    "Btu is a unit of energy not power, not sure why you would need Btu values. Usually things like backup power supplies are rated in Watts or kilowatts.

    But here is how you would do it.

    Amps * Volts = Watts
    Watts * hours = watthours
    watthours * 3.41214148 = Btu

    So you would need to know amps, volts (usually 120 or 240), and the number of hours."

    With this math I get 3.3 Amps X 240 Volts = 792 Watts
    792 Watts x 1 hour = 792 Watthour
    792 Watthour x 3.41214148 = 2702 BTU

    With the rate of 34 BTU's per square foot I get 2210 BTU's

    Which one is right?

    Thanks,

    John Whipple
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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  4. Thatguy

    Thatguy Homeowner

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    Cable heat electric flooring has significant heat loss into the ground so you'd need more power to get the same air temp. increase as a space heater.
  5. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Warm Tiles Heat Cable

    http://www.warmtiles.com/ I have been using this one type of cable for all my jobs over the past 6 years. In all but two bathrooms we only used this cable to heat the floors.

    We make sure the room is insulated properly and use spray foam under the floor where the bathroom is over an uninsulated room.

    I have never had a heat complaint or felt cold in these rooms.

    I received an email from Easy heat yesterday stating that they get 40 BTU's at the 3" spacing and 51 BTU's from the 3" 1 1/2" 3" spacing pattern.

    Here is Andy's contact information so you can check your install, your specific kit (120v/240v etc.)

    Andy Cowell
    EGS / EasyHeat
    Andy.Cowell@emerson.com
    Phone: 860-653-1604
    Fax: 860-653-4938

    Every room has there own mechanics so an HVAC engineer should be consulted as to what BTU's you need from each room. Once armed with this information you can work out which cable will do the job. There are many good online calculation sites as well - I have yet to try one as my calculations where done for free by Bartle & Gibson here in Vancouver. i paid $75.00 for this service but was credited this back once I bought my boiler from them.
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