I’m just getting started on an addition I’m building and the home owner is asking about electric floor warming systems. what im looking for is others opinions on what they think. i ve used these systems in smaller area like bath floors but they want about 300 sf ft. any comments welcome, for sake of discussion. thanks
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Replies
It can take the chill off of floors, but won't have enough watts to heat the whole room.
What Wayne said. It shouldn't be considered as a primary source of heat.
FYI, I see at Home Despot a newish product that lets you wind a single strand of heating cable around little plastic disks fastened to the subfloor. 120V or 240V. This is a great feature IMO. Previous products have had a hard time dealing with awkward contours around plumbing fixtures, millwork, doors, etc. You can pretty much do what you want with this one.
Sorry, I can't remember the product name, but I'm sure you can track it down. Let me know if not.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
NuHeat will custom build a mat in either 120 or 240 volt. The web site lists up to 200 sq. ft. and you can put more than one mat in place. Or they may be able to make a bigger one for you. It takes about 10 days to get one.
They do only take the chill off as has been mentioned. I'm not sure they make sense in a bedroom with a lot of moveable furniture. Why heat under the bed? But since the furniture could be rearranged, I'd think you would have to heat everywhere.
http://www.nuheat.com/products/
I'm a little surprised at the "they only provide floor warming" bit... I don't expect to hear that about electric mats.Is this very true, or are these just getting thrown into rooms with carpets and/or higher heat loads and people aren't doing the math.1 watt = 3.41 BTUs/hr. Do the math and it *should* work out ok... just need to know your BTU load. I don't use electric personally, so please don't be shy if I'm missing something. I just hear people claim similar things about hydronic radiant a lot and I know it's not true there, so I thought I'd check.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
>>>Is this very true, or are these just getting thrown into rooms with carpets and/or higher heat loads and people aren't doing the math.Good question. The typical load calc for electric heat when using baseboard heaters is 1000 watts per 100 sq. ft. of floor. Most in-floor heat uses about 12 watts per sq. ft. which amounts to 1200 watts per 100 sq. ft. Should be plenty right?But there are other issues to consider. Depending on what is under or over the in-floor heat there may be loss, especially if the floor is a cement slab with little or no insulation under it. Secondly, because this is electric heat, it is expensive to operate, and people often don't want to leave it on all the time. If you can heat the room with something else and just gently warm up the floor a bit you'll save money. We plan to put a timer on ours so that it only runs for a few hours in the morning (in a bathroom).Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Heck, 12 watts per square foot is better than most hydronic radiant methods and should be warm enough to make the floor surface uncomfortably warm in most cases. That's 40 BTUs/sq ft.. twice the average for an average home.. and at the maximum output for a floor before people start complaining of hot feet, typically.I don't know what temperature the elements really run at though so the floor covering resistence could bring that down quite a bit, and you're dead right about those uninsulated slabs and operational costs. But it sounds like it has the capacity.. question is how it is applied. insulated underneath, etc.I probably should study up sometime. -------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com