Peggy Burgus
New Member
Please tell me all that you know about functional under floor heating. What works? What doesn't work? Can the shower floor be warmed this way, safely?
Heated tile floor in bathroom
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Erico
Member
Between my own and for friends, I've installed 6 heated floors. I've always used the sun touch from big box stores. The pre-.wired mats. Or the laticrete brand from lowes.
There are other brands and spools of wire you can custom build but I've never used those.
I've always set mine in self leveling cement using the procedure spelled out on the John bridge tile forum. I tried the "one step" method of combing the mat in thinset but didn't like where that was going so I aborted. Much rather tile on a super flat surface and not worry about creating voids to cause me tile problems later. There is also the extra benefit of protecting the wires from trowels and other tools.
In a couple cases I cut the mat(not the wires) to make turns around corners. In at least one case, I used two mats. My understanding is that some manufacturers will make a custom mat but I've never needed to go that route.
Do follow the instructions on testing the wires with an ohm meter before, during, and after installation.
I did read a suggestion after I installed mine about buying an extra thermostat sensor wire to embed under the tile as a backup if/when the original thermostat sensor wire fails. Don't know if you can buy an extra separately but that seems like a great idea as sensors are probably the first thing to fail (common in car radiator sensors and furnace sensors).
Keep your distance from toilet wax rings and don't install in a covered floor area like under cabinets. You can't use a rug when the floor is in use. I've left a towel on the floor and am surprised how hot the floor gets when partially covered. I will say I don't think the heat radiates as far as they advertise so if you have a spot where you want your piggies to be warm make sure you set wires there or very close - like under a pedestal sink or toe kick.
Not sure but I think I've seen some specs that allow in a shower. I wouldn't do it but you could check with the manufacturer. Seems silly to me to warm a floor that is going to have hot water pouring on it before I set foot in the shower.
I absolutely love our heated floors and wouldn't build another bathroom without it.
There are other brands and spools of wire you can custom build but I've never used those.
I've always set mine in self leveling cement using the procedure spelled out on the John bridge tile forum. I tried the "one step" method of combing the mat in thinset but didn't like where that was going so I aborted. Much rather tile on a super flat surface and not worry about creating voids to cause me tile problems later. There is also the extra benefit of protecting the wires from trowels and other tools.
In a couple cases I cut the mat(not the wires) to make turns around corners. In at least one case, I used two mats. My understanding is that some manufacturers will make a custom mat but I've never needed to go that route.
Do follow the instructions on testing the wires with an ohm meter before, during, and after installation.
I did read a suggestion after I installed mine about buying an extra thermostat sensor wire to embed under the tile as a backup if/when the original thermostat sensor wire fails. Don't know if you can buy an extra separately but that seems like a great idea as sensors are probably the first thing to fail (common in car radiator sensors and furnace sensors).
Keep your distance from toilet wax rings and don't install in a covered floor area like under cabinets. You can't use a rug when the floor is in use. I've left a towel on the floor and am surprised how hot the floor gets when partially covered. I will say I don't think the heat radiates as far as they advertise so if you have a spot where you want your piggies to be warm make sure you set wires there or very close - like under a pedestal sink or toe kick.
Not sure but I think I've seen some specs that allow in a shower. I wouldn't do it but you could check with the manufacturer. Seems silly to me to warm a floor that is going to have hot water pouring on it before I set foot in the shower.
I absolutely love our heated floors and wouldn't build another bathroom without it.
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Jadnashua
Retired Defense Industry Engineer xxx
Depending on where you live, the building code may require that electrical heating be installed on a timer with the maximum on-time of 30-minutes! CA is one of those areas. FWIW, most systems are designated as floor WARMING systems, and not room heating. Depending on where you live and the heating requirement of the area, it MIGHT be enough, but would again, be problematic depending on where you live, since you couldn't legally, leave it on for room heating.
To be useful under those circumstances, you'd want the heating wires as close to the bottom of the tile as possible. Depending on the system you choose, and if you embed it in SLC, you might have a significant thermal mass, and 30-minutes may not do much!
Schluter's system - DitraHeat overcomes some of those issues. It CAN be installed in a shower, but only if done exactly as they say in their installation instructions (basically, you'd need to make a Kerdi Shower - check their website at www.schluter.com). Because DitraHeat doesn't have as much thermal mass because of its structure, and that structure has a matrix of air channels, the heat tends to be distributed more evenly and faster than other techniques.
FWIW, while use of an ohmmeter is important to verify you have not broken a heating mat or wire system, it won't check that you've damaged the insulation which can lead to corrosion and failure, often at least several years down the road. As a result, Schluter requires that you use a different tool - a megohmmeter. This device not only verifies no shorts or opens, it also tests the insulation. If you don't, the warranty is void. Most brands, in the fine print, suggest you do this, but do not require it. Schluter is very conservative and wants it to work long-term, so they require it.
Most heating mats/wires can produce at the max about 12-14W/sqft, which equates to about 40-48 BTU/sqft. Now, note, that depending on the room, you might not be able to get those maximums, as there's a limit on how hot you can safely make the floor.
To be useful under those circumstances, you'd want the heating wires as close to the bottom of the tile as possible. Depending on the system you choose, and if you embed it in SLC, you might have a significant thermal mass, and 30-minutes may not do much!
Schluter's system - DitraHeat overcomes some of those issues. It CAN be installed in a shower, but only if done exactly as they say in their installation instructions (basically, you'd need to make a Kerdi Shower - check their website at www.schluter.com). Because DitraHeat doesn't have as much thermal mass because of its structure, and that structure has a matrix of air channels, the heat tends to be distributed more evenly and faster than other techniques.
FWIW, while use of an ohmmeter is important to verify you have not broken a heating mat or wire system, it won't check that you've damaged the insulation which can lead to corrosion and failure, often at least several years down the road. As a result, Schluter requires that you use a different tool - a megohmmeter. This device not only verifies no shorts or opens, it also tests the insulation. If you don't, the warranty is void. Most brands, in the fine print, suggest you do this, but do not require it. Schluter is very conservative and wants it to work long-term, so they require it.
Most heating mats/wires can produce at the max about 12-14W/sqft, which equates to about 40-48 BTU/sqft. Now, note, that depending on the room, you might not be able to get those maximums, as there's a limit on how hot you can safely make the floor.
Erico
Member
Really? Only thirty minutes? That sucks. How do you heat a floor in 30 minutes?
We set ours at 84 all winter. Had to fight with the spouse to turn it off in the summer - yeah I know. Lol, not paying to air condition the room to fight with the floor heater.
Jadnashua
Retired Defense Industry Engineer xxx
The green energy codes prohibit the use of electrical resistant heat as the primary source of space heating, and it can get messy if you want the floor warm all of the time, or don't want to wait for it to happen. It is tough to get fast response when you have a large thermal mass, as there's a limit on how hot you can make the wire and how much energy you can put into the system. This is one reason why something like Schluter's Ditra can help since it uses less mortar around things than embedding the heating elements entirely, and also has air space to help that heat spread around through convection as well as conduction so the response times are quicker.
Not every place has (yet) these rules, but it is spreading regarding the 30-minute max.
Erico
Member
They can have my constant heat floor heater when they pry it from my cold chubby piggy toes.
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