Heating Cable install - No thermostat desired [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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06-19-2012, 04:07 PM
Hi there,

I'm installing an in-floor heating cable in my basement bathroom and wish for it to be operated by a simple 5/10/15/30 minute timer, rather than the fancy thermostats which are recommended.

Based on what I've read, the thermostat simply functions as an automated on/off switch, alternating between on/off in correlation to what it is reading from the temperature sensor installed in the floor.

In theory, the heating wire could be hooked up to a timer switch and would just be set to on when the timer activates.

To those familiar with in-floor heating cables, have you seen this done? Thoughts?

The heating cable - True Comfort Systems heating cable

The suggested thermostat - True Comfort Systems thermostat

My desired timer - Leviton Decora 5-10-15-30 timer

(sorry, I couldn't post links)

Thanks in advance for your input.

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06-19-2012, 06:07 PM
To actually warm a floor, it likely would need to be on for longer than your timer allows. Especially on a basement slab...there's a huge amount of mass, the wire doesn't produce a lot of heat, and it generally needs to be on quite awhile to bring the slab up to temp, then it will cycle on/off to maintain it. A timer may be a viable choice over a wooden subfloor, but not likely on a slab.

Houston Remodeler
06-19-2012, 06:31 PM
The other thing to pay attention to is the wattage of the switch you intend to use and the wattage of the heating system. If the heating system surpasses the on off switch then you are SOL. At best the heating system shouldn't be more than 90% the capaacity of the switch. Many of the more modern dimmers and timers have very sensative electronics which don't mix well with the peak demand loads of a heating system (brown outs) If you want to try the on / off switch have at it, but I'd wire it the same as a thermostat so when the on /off sitch fails you can add the thermostat.

06-19-2012, 06:39 PM
Nice idea, but its not going to work like you think.

On a slab, it will take 30 to 45 min before you notice anything at all, and then it will be faint. After an hour you can say it feels warm.

Buy the thermostat and forget about it, your feet will be happy.

06-19-2012, 08:39 PM
You could add a time-of-day timer in, if, say, you only wanted it warm in the morning. You'd turn the timer on maybe an hour or probably more early, but with that large of a thermal mass, it's really unlikely you'd get it warm in anything like a timely manner...it's not like a ceiling heatlamp only heating the air.

06-19-2012, 09:19 PM
I donít know the details, but my guess is that an in floor thermostat does not work at all like you are thinking. My guess is that it very little to do with the room temperature and a lot to do with controlling temperature gradients and the associated stresses within the floor. Now it may work just fine without a thermostat, especially when installed on slab, but that is not an experiment I would try in my house. If it doesnít work correctly, you will not be able to retrofit a thermostat. You can always wire a timer in front of the thermostat and have both.

06-19-2012, 10:27 PM
A thermostat with a built-in timer is usually an option (more expensive) with these systems. I opted for the timer and have it set to come on only in the mornings and the evenings, and I guess I save a few cents that way (though the manufacturers claim their systems cost only pennies per day).

06-20-2012, 08:15 AM
Let me just add the fact that most of the thermostats have the GFI built into them. If you chose to not install a thermostat , you still will need to add a GFI somewhere in the feed. Buy the thermostat and adjust the settings to your lifestyle. You already made the hardest choice - you want warm floors!