Electric Mat Under Tile - Any Major Differences?

Tremolux · February 2011

We've decided to retrofit forced-air into our 1930 brick restoration project rather than replace the frozen cast iron. ( great expense & couldn't trust the pipes. )

Since we've taken out the floors of the 1st floor kitchen and bathroom, and plan to install tile, we'd like to supplement the heat with a warm floor. ( The depths of Midwestern cold preclude effective heating under the wood floors with hydronic systems. )

Are the several brands of under-floor electric mats all about the same, or are there some significant differences in durability and/or efficiency? Any that are particularly tricky to install or "finicky" in operation?

Thanks for your time and attention.

EricAune · February 2011

"Midwestern cold"

Where are you located? While geography may play a role in the ability to provide enough heat to an area, I have on numerous occasions successfully installed underfloor systems with very little need in supplementals. I, by the way, reside and work in one of the coldest areas of the mid-west; Minnesota. Our design temperature is a balmy -12 to -15, depending on your location and my floors are warm as I type.

Operation costs are the prohibitive factor with most electric radiant floors. Are there any special rate programs available to you for electric heating? Dual-fuel? Service interruption? Without these types of programs most of the installations in my area sit idle due to their high cost of operation.

Gordy · February 2011

Operating costs

As Eric pointed out could kill how enjoyable the floor is to use. I know in the Chicago burbs we are at 12.5 cents a Kilowatt. That's high, and comed is bucking for increases.

Also with electric mats you are committed to one energy source the only other option you have to power it is off grid hardware like solar, or wind. With hydronics the boiler can be selected for the cheapest fuel to run.

There would be nothing worse than installing a radiant floor, and not using it because it costs to much to run. Or committed to using it because you have to heat the space with it.

One other thing is can your present electrical service handle the additional load, or will your service need to be upgraded. Example 100 amp to a 200amp service up grade involves more than a bigger service panel. You need to also up the size of the feed wires to the service.

If your really stuck on the electric radiant I all ways thought ZMesh was a good product.

Tremolux · February 2011

Slight Clarification - Supplemental Source

Thanks for the feedback.

We're not as cold as Chicago, but this Winter in St. Louis was a bear.

Ameren electrical rates range between 5 & 7 cents per kwh, from Oct. - May.

The size & shape of the kitchen, with a large window ( new 2X pane ) and two outside facing brick walls plus a porch door, would have been a bear to heat with any under floor hydronic system.

We only intend to use the electric mats to take the edge off the cold tile floors. The actual heating of the rooms will be from the forced air ducts.

Would mats be effective in that role, at those rates, without breaking the bank?

We upgraded from fuses to breakers, but still have 100 amp service for two floors. Do those mats draw a lot of amperage?

We're a little hesitant to go this route since the electric towel warmer we installed in a bathroom renovation almost never gets used.

While we're on the subject of electrical additions, how many electric saunas actually get used as something other than a new closet? Our spouse has had one of those on her mind for years.

Gordy · February 2011

Rates

When I speak of 12.5 cents a kilowatt that is after tax title, and license ( what you pay divided by the kilowatt hours used) not the quoted kilowatt rate before fees.

100amp service is bare minimum now days with all the appliances, and such we feel the need to power. If your kitchen is large it would require a 220 volt setup. Which may be feasible with a piggy back breaker box, just depends on your usage. Something a qualified electrician needs to decide.

Saunas, roman tubs, and the like to me look nice, and get used like my wife's must have treadmill. Next thing you know its a clothes rack. We are shower type of people tub rarely gets used. Saunas take a while to energize. Pretty soon its to much of a bother once the new thing euphoria wears off. But then I'm a simple guy.

Tim_75 · February 2011

Differences, not major

I have installed several varieties of these in my home. There are three items of concern.

One is the heating element and it installation. These are wires of some form either rolled off of a spool and clamped/stapled down or woven into a matt. The roll version costs much less but is more tedious to install and required more height. The matt versions are very thin and much easier to install, but that comes at a price. Having installed both, I always use the matt.

Second/third are the controllers and sensors. Two different ways to control the floor heat: floor temperature and air temperature. Again, I have both and they are both good, but for different reasons. I have a night setback on my heating system and tile floors in every bathroom. The most likely time that I would be barefoot in a bathroom is in the middle of the night or early oin the morning. The one controller I have that activates the floor heat based on air temp is in the masterbath. Love it! (BTW, 660 watts of heat in this room runs on a dedicated 120V, 15A circuit is plenty of heat in a 14 x 8 room with two windows and two exterior walls, in N. IL). This particular controller has an internally settable floor high temp limit and is only manual. So when the air temp drops at night, the floor is much more likely to be keeping the tiles warm and toasty. The other type I have controls based on floor temperature with an imbedded sensor. These (NuHeat brand, also the matt type) came with a wonderful Aube digital programmable controller. I prefer the programmable versions in most places. Since all of these systems are installed very near the surface under thin and relativly conductive tiles, they also respond very quickley. I have imbedded tubes in a concrete slab in my garage and that system will raise the space temperature about 5 degrees in 20 to 30 minutes. The electric under tile would do the same in less than 10.

I have Commonwealth Edison as my electric company, the same utility that serves Chicago and its is not one of the best deals in the country. I don't notice a significant difference in my electricity costs using the supplemental electric infloor heating systems. Between aquaria and koi ponds and the associated water movers, heaters and the like, I use a lot of electricity, so maybe that's why. Bu these are primarily "floor warmers" and not intended to be the sole source of heating for a space. The cost of LP (my fuel of choice) is 10 times my electricity in a very cold month. We see -10 to -20 every winter and that is about the limit of my gas (LP) fired system. The extra capacity of the tile warmers is nice to have when it gets to -20.

Personally, I will never have tile floor in my house that is not heated, either hydronically or electrically after having lived with it for so long. Warm floors everywhere, all the time are over-rated and at this place over-hyped. Warm tiles in your bathroom are a wonderful thing. You will never regret it, no matter which version you choose. I have installed the Infloor brand and the NuHeat brand and recommend the latter. The operating cost of these floor is minor compared to the benefits.

Good luck and stay warm!

Tim_75 · February 2011

ComEd rates

are not that high in the winter, early spring and late fall months. There are higher residential rates in the summer, but that doesn't apply here.

Gordy · February 2011

Take a look at the zmesh by Heatizon systems

I do not sell it, or have I used it. What I like about it is that it has almost zero build up, easy to install, not as sensitive to broken wires in the grid and it has very even floor coverage . It can also achieve up to 40 btus a sf. at 12 watts a sf. But that puts floor temps way above the 85* thresh hold for comfort.http://zmesh.com/

One draw back is all the mesh systems are 220v which is not a big deal if the service is capable. The TuffR cable system does come in 120V for smaller areas

If you use Tim's floor at 660 watts. If it runs for 12 hours a day that equates to .99 cents a day at 12.5 cents a Kilowatt hour. Or 30 bucks a month. Not bad for warm floors.

Gordy

Electric Mat Under Tile - Any Major Differences?

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