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Radiant floor heating in bathroom

5K views 13 replies 8 participants last post by  dcholly 
#1 ·
I have a very small bathroom (5'x6') that I am planning to remodel. I want to remove the radiator to save space. Is a small section of electric radiant floor heating enough to heat this room, as well as the floor? Or should I install a small baseboard or thin radiator to go along with the electric floor heating? Thanks.
 
#3 ·
I have found that the "warm tiles" system could possibly tackle this, if spaced at the 1-1/2" increments. I installed one of these systems in my bathroom spaced at 3" increments, and it maintains the temperature through the night, set at 1/4 of temp setting (the termostat is marked 1-10, not actual temperature). My intent was to prevent the cold tiles (bath over crawl), not so much primary heat, but looking at installing one in my mudroom for that purpose, since there is no way to get forced air heat to it.
 
#4 ·
My installation is over (2) layers of 3/4 sub-floor, then the wire embedded in floor level mix...then the tiles
My basement usually stays around 57-63
I can turn it off & turn it back on an hour before I want the temp
I opted for the programmable thermostat
It goes up to 70 an hour before we get up in the morning

Another person I know installed his on a concrete floor & needed to leave it running 24x7 at the Temp he wanted
It would take a day or longer to get up to temp

One sites info:

Expected floor temperature
The floor temp attainable is dependent on how well the floor insulated,
temp of the floor before start up, and in the case of uninsulated slab applications, the thermal drain of the underlying materials.

These are the three most common installations:​
1. Wood framing:​
With the cable installed on a well-insulated wood subfloor, and thin-set mortar and tile on top, most floors can be heated up to 20°F warmer than they would otherwise be.

2. Insulated concrete slab:​
With the cables installed on an insulated concrete slab, and thin-set mortar and tile on top, most floors can be heated up to perhaps 15°F warmer than they would otherwise be.

3. Uninsulated concrete slab:​
With the cables installed on an uninsulated concrete slab, and thin-set mortar and tile on top, most floors can be heated up to perhaps 10°–15°F warmer than they would otherwise be.

 
#5 ·
If you do go with the tile system do yourself a favor and just do the entire bathroom (minus where permanent fixtures will be of course).

My parents got it installed when they did their basement bathroom and opted to just do a small section, the rest of the tiles were always very cold. IF you're going to do it, may as well do it right! Once the tiles are down, there's no turning back... well there is, but it's not pretty. :laughing:

I don't know much about the electric ones but I'm guessing they come in different wattage per square feet, if you actually want to heat the room get the higher wattage one. The one my parents had did a slight difference in the room temp but it was mostly meant to just keep the tiles warm. It had to be kept on all the time, no thermostat or anything. Same idea as heat tape I guess.
 
#8 ·
Thanks for the advice, guys. I am still waiting for a total price from the remodeling contractor. When I get that, I'll find out if this is even an issue :) I like the idea of doing the entire floor. The contractor mentioned that you don't want to do near the toilet since it could melt the wax ring. Is this true? I would like to do the whole floor, including where your feet would go while using the toilet.
 
#10 ·
Yes, you do need to stay away from the toilet wax ring
Keep in mind the wax ring is already ~3" away from the edge of the toilet
My installaion required an additional 3" away from the toilet edge
If you have a cement slab floor additional distance may be required

On my floor 3" away from heated area is cold tile
Same 3" clearance distance is around each wall, vanity & the tub
My heat goes all the way to wall, so both feet are warm
 
#12 ·
Technically, if you are planning on installing a radiant system in the bathroom as a primary heating system, the correct way to know how to size it is to complete a heat loss calculation on the room. This will give you the correct btu/watts of loss per hour. To throw out some numbers, if the room is losing i.e. 2500 btu's / hr, you'll want to put a system in that is at least 3000 btu's (more is always better) to recoup more heat than you are losing. The numbers won't lie. And, the more watts you generate, the faster it will recoup and the less time it will be on to do it. Naturally, it will cost more to run but if you put in less watts psf, then it will cost less to run but will need to run longer to maintain. So, it balances out in the end.

On the other hand, if this room is interior, has no windows or exterior walls, just about any system you install that fully covers the open floor area will work. Keep 6" from the ring, that's will be fine. None of the heating elements ot there heat more than 3" out from the element. Definitly use a digital programmable thermostat. It must be a GFCI unit if you use a line voltage radiant system. You don't want to use a GFCI for a low voltage system.
 
#13 ·
My bathroom is approx 41 sq ft including where the tub is located & vanity
Heated floor is maybe 21 sq ft @ 15w per sq ft per Mfg =~300w
Also heated is the 30 sq ft hallway directly outside the bathroom = ~400w
One outside wall - 7' long - R13 insulation
Total is as I remember ~6a = 720w all together

Works very well, planning the same thing for upstairs bathroom - under tile
Then 2nd bathroom will have a 600w "towel warmer" that doubles for heat

I wish electric cost was lower here, its a nice way to heat an area
 
#14 ·
This sounds promising. I too would like to replace my radiator in the bathroom with radiant heating. I also use a space heater in the winter as the bathroom gets cold due to the exterior wall which doesn't have a lot of insulation (house was built in 1910). It sounds like I will be able to do this. I am also interested in installing bamboo flooring and was wondering if I can do both or I need to use ceramic tiles as the heat will be too much for the bamboo floors.
 
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