Problems with electric Floor heat under ceramic tile

I installed a "warm tiles" electric floor heat system under my ceramic tile. My problem is that the temperature will not exceed 72 F. It takes at least an hour if not more to heat to 72 and then will not heat beyond that. I have a programable thermostat with a floor sensor. The heating indicator stays on all the time, that says its continuously heating (I left it for a 24 hour period) but it will just not heat up to a good temperature. Any suggestions on where to start looking?

My first question would be, what is your subfloor?

2nd question is the space below heated or unheated?
3rd question did you follow the manufactures installation instructions?

Ok,

Subfloor is wood, on which I installed 1/4 inch cement backer board, and the tile on top of the backer board.

This floor was laid in an upstairs bathroom and the basement is down below and is heated.

The install was exactly per the manufactures instructions.

Are you talking floor temperature or air temp? Most of those are designed for somewhere between 7-15 watts per square foot; not much. Most are not designed to actually heat the room, but to warm the floor. The room may get a little warmer, but no guarantees; depends on lots of factors. At the high end, 15W/hr=just over 51BTU. Say you've got 50 square feet, and max heat, that's only 750W...most small electric space heaters are 1100-1500W, so one of them on medium is about what you've got.

Did you install their mat's or wire? Could it be that you have 240v product on 120v? What is the sf of the area of the Warm Tile?

I have never used the Warm Tile product, but have installed many floors with other makes. Even on a slab with .25 inch Wedi board and block walls, there has been no problem getting to the lower 80's in a little over an hour.

Have you checked the floor temp with anything besides the probe connected to the thermostat? You may want to speak with the Warm Tile folks, could be a wacky problem with the thermostat. There are two flavors of thermostats, one responding to air temp, the other to floor temp. The floor temp version will give you the best economy.

Thanks for your responses.

I am talking about the floor Temp, I never expected to heat the room.

I am using the wires installed on the backer board with the plastic strips that came with the installation kit, not the mats. Both the wires and thermostat are the 120V kind.

I should note that I did a skim coat of mortor over the wires, let them dry and then did the mortor over top wear I laid the tiles, but it should still be well within the manufactures specs of having the wires 3/4 of an inch from the top of the floor.

I am using the sensor that I installed in the floor and it is taking the temp reading inside the floor, not the air, but I have not checked the floor temp with another source with the exception of my hand which on which I could feel some tiles slighly warm but not what they should be.

The room is about 50 FT2.

I have a call in to the technical support but they have not called me back.

Maybe I should check the wires at the thermostat, but that wouldn't make sense as it shows that the floor warming is ingaged for hours but the floor temp won't increase.

What is the spacing of the wires, and based on that spacing what is the rated wattage per sf?

Could be that for the mass you are heating you just don't have the watts per sf to heat it beyond the 72 degrees.

You get 3.413 BTUs per hour per Watt applied to the circuit. That is what you get no matter how you installed it. That is physics and is guaranteed to work.

What are specifictions of what you installed? How many Watts per unit of length, or for each element?

If you wired multiple units in series (one after the other) instead of in parallel, they will produce less heat.

Where is the sensor in relation to the nearest heating wire?

Thanks again for the responses.

I installed the wires at 3 inch intervals. The sensor was put right near one of wires about 1 1/2 - 2 inches away from it, as per the manufacutures instructions.

I didn't get the ratings on the wire, I will do that.

It it possible that I installed the wrong breaker? Would that not allow enough power to the unit? Although the draw is pretty low, so I don't think that should affect it.

If the breaker doesn't trip, it should be fine. If you can get the info on the wire that was installed, it should be possible to see how much heat it should produce. It's possible it is not hooked up properly. Do they tell you how to check it? If you disconnect the power, then the leads from the thermostat, using a multimeter set to ohms, what is the resistance of the installed wire? What voltage is applied? Those two things would go a long ways towards figuring out how much power it is drawing, and therefore how much heat it will provide.

It would help if you had an IR thermometer so you could verify actual floor temperature.

The thermostats used with these systems are relay controlled, either off or on. Some are adaptive in that they will learn heat loss, and adjust their cycle times.

The fact that you are seeing indication of being constant on and the temp is not going past 72 degrees leaves only a couple of problem areas. Bad thermostat, for a couple of reasons. One being that they do have a max temp where they will cut out, which could be out of calibration. Or, some other issue with the thermostat. You can easily verify the thermostat's action with a volt meter.

If that is not the case, you are back to the wire. Braid to neutral, internal conductors to the power source via the thermostat. Check the resistance of the wire per the manufactures spec's for 110v wire. If that checks out, you are down to spacing of the wire in the floor, and your heat loss.

Did you happen to find a solution to this? We are experiencing the same problem. I've verified everything but no luck....
Thanks in advance,
Jm

I need some advice. I have warming tiles in my basement bathroom floor. They worked for about 2 years and now they dont. I have tried to mess around with thermostat using auto setting and nothing happens when it is suppose to turn on and manual wont do anything. Please help?

A couple of things:
- make sure that there is actually voltage being applied
- if there's voltage, turn it off, disconnect the power leads to the floor, then check to see if the floor heating elements are open. Depending on how long the run is, and how much heat it is supposed to generate, the actual resistance reading will differ, but it should be in the 10-s of 0hms maximum, not open (infinity).

The thermostat could be bad, if there's a floor sensor, it could be bad. One thing that almost nobody does when installing these things is to perform a megometer reading. The most that people generally do is perform a resistance test. When using a megometer to test the install, it not only tests the conductor, but also the insulation. A problem with either one in the long-term can create a failure.