Floor warming system being installed. Warm Tile Floors For The Bathroom:

Installing Floor Tile Warming Cables

 
In This Article:

Electric tile warming cables are installed in a serpentine pattern. Some problems are encountered but resolved. Discussion of laying tile over warming cables.

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Skill Level: 4 (Advanced) Time Taken: 4 Hours

By , Editor

 

In our old house bathroom remodel we wanted an elegant floor that was durable and timeless. That precluded vinyl flooring. Ceramic tiles are man-made and tend to reflect current fashions. We didn't want to install a tile that looked great today but looked out-of-date in a decade.

So the owner settled on marble. We found a very pleasant beige Turkish marble at a store called Menard's (a mid-west chain) for $6 a square foot.  

But we also wanted to stay away from the cold feeling of tile, so we investigated various electric floor heating systems. We needed something that was thin enough to install between the tile backer and the tile itself. After looking at a few web sites we came across Warm Tiles by Easy Heat. We found a local electrical distributor and were pleased by the fact that they had sold several systems locally. The homeowner bought two spools of cable and a set-back thermostat, which totaled almost $500 for about 100 square feet of tiled floor area.

Read on to see if it was worth it.

 

Before installing the heating cables I snapped a chalk line to establish a baseline for laying the tiles. 

 

Following the manufacturers instructions, I laid out a pattern with 3" spacing between adjacent loops.

There were two separate runs of cable that entered the control box, which meant four wires, plus the temperature sensor cable.

Laying out locations of floor warming cables.

The cable is run as an out-and-back serpentine loop. The wire cannot be cut to length or modified in any way. Only the special ends can be trimmed back. Connections are not permitted anywhere in the loop of wire.

 

The package contained a spool of cable and a roll of plastic "track" for securing the cable to the floor.

 

The special ends of the cable have a black sheath. The wire with the white insulation is the current-carrying wire. The other wire is the braided ground that encompasses the cable.

 

The track has notches every 1-1/2".

 

I installed the track a few inches from the "loop ends". I used the "Rock-On" brand screws that are meant for installing cement board.

 

The installation progressed fairly rapidly. I did the small bathroom first, because it is farthest from the thermostat connection.

 

The short loop (red arrow) between the shower and the vanity is important for adjustment purposes. Since you cannot cut the wire to length, excess wire must be placed somewhere out of the way. I chose this little sliver of space between the shower and the vanity. The length of this loop could be varied depending on how carefully I laid out the cable and how accurately I estimated the cable length when purchasing it.

 

The cable approaches the doorway to the bedroom, but is kept 6" away from the walls.

The Second Room:

Following their instructions, I put the spool of wire on a stick (a broom handle) to allow the wire to freely unwind. This helps reduce the problem of twists and kinks in the wire.

 

The cable just snapped into the notches in the track. The track works best when placed close to the end of the loops, so the curvature of the wire helps pinch itself in place.

 

But... the wire kept coming out of the track. I ended up applying masking tape over all of the tracks to hold the wires down.

 

Near the thermostat I made a groove in the cement board by drilling a series of holes with a 1/2" masonry bit. The black ends of the cable are much thicker than the heating sections, and I didn't want this thicker cable to interfere with laying tile.

 

To connect the holes, I drilled on an acute angle, letting the bit just skip across the holes and dig out the cement board.

 

When I tried to stuff four wires through the 1/2" conduit that I had installed a few weeks earlier, I ripped the jacket on one cable. This is not good.

And herein lies the biggest problem I found with Easy Heat's product. During the electrical rough-in, I ran an ordinary 12 gauge cable to a 4" square metal box for the thermostat. Easy Heat supplies a roll of string to use as a "wire fishing aid". You are supposed to let the string dangle from the thermostat box, down to the bottom plate of the wall, and through a hole in the bottom plate out to the floor. This entire concept seemed hokey to me. I wasn't going to rely on a little piece of string to complete a crucial step of a $500 product. So I decided to install EMT thinwall conduit.

Easy Heat's web site had no information on what size of conduit to use. At that early stage I had not even seen the heating cable, let alone purchased it. I called the local distributor and asked a salesman about conduit sizes. He didn't know. I called the technical support phone number for Easy Heat and spoke to a young-sounding rep. He indicated that since the wire gauge was number 14, I should be able to fit four of these conductors into 1/2" conduit.

WRONG! I could barely fit two of these special coaxial wires through the 1/2" conduit that I installed. There was no way that I could fit four conductors and the thermostat sensing cable. 

It became clear to me that I should have used at least 3/4" conduit for two loops of heating cable.

So during cable installation, many weeks after I installed the conduit between the floor and the junction box, I had a sudden change in plans. I made the temperature sensing wire (red arrow) and two of the heating wires, go underground. I drilled holes in the floor and poked the cables down under.

 

In the room downstairs, which fortunately was also being remodeled, I made a short jog in the wires and fished them up the wall cavity near the thermostat. The white cable is the line that feeds power to the thermostat. 

It pays to remodel rooms that are vertically adjacent .

 

Just below the thermostat box, I cut a big hole in my recently finished drywall job so I could fish the wires into the junction box.

 

The large bathroom, after the cable had been installed. The two wires at the right (just in front of the bath tub) are the heating cables to the smaller bathroom.

 

Another view of the large bathroom's heating cables. Note how cables are not installed under the vanity and the toilet. Easy Heat also recommends keeping the cable up to 6 inches away from walls.

 

Only two wires occupy the conduit. This conduit is a section of straight pipe and a simple curved piece that was cut off and filed smooth to remove all burrs. 

 

The loop of wire next to the wall is another "adjustment loop". This is the last section of wire to fasten down. The length of the loop depends on how carefully the floor area is measured and how carefully the serpentine cable path is laid out.

Laying The Tile:

This was the first tile job I had ever done. I'll admit that it's risky to learn a skill using $600 worth of marble on top of $370 worth of floor heating cable. But I had seen many people do tile work, and I did some research on tile laying. I bought the recommended tools. I bought premium mortar.

Since it was new to me, I didn't take any pictures of the tile laying process. It really takes two people to photograph the tile laying process, and I didn't have a helper for enough hours in a day.

There was a problem with the Easy Heat floor heating cable system. Their plastic "track" was too thick and kept getting in the way. I often had a tile that was too high on one side, yet could not be pushed down because the plastic track was holding the tile up.

So after laying about 15 tiles, I began to remove ALL of the plastic track, one section at a time. I would lay the tiles in the center of the field, where there was no track, and these tiles would hold the wires in place just fine. Then I would remove the track just as I got close to it, and use masking tape to keep the loop ends in place while I tiled over them. This was a minor nuisance but it worked well.

 So... Is It Worth It?

When I installed the heating cable and laid the tile, I had a few doubts about ever doing this again. But... after using the heated marble floor for a few winter months, I can say that heated floors are very much worth the extra money. I will never install a tile floor in a "barefoot traffic area" without some form of floor heat. It is so pleasant to walk into a room with bare feet and have the floor feel warm instead of cold. And when I stand near the wall, I can feel the unheated floor. What a difference! I cannot imagine having an unheated tile floor in winter-time in Northern Michigan. I have seen some rather expensive houses with tile or marble bathroom floors... and the homeowners cover the entire floor with rugs because it is so cold. What's the point of installing marble only to have it covered up half the year?

Electricity usage has been negligible, even though the two runs of heat cable consume about 500 watts of power. The thermostat has been kept at a low-to-medium setting, but the thermostat only has to turn on for a few minutes every hour in order to maintain a "not cold" floor temperature. If a truly warm floor was desired (and this system can definitely deliver that) then more power would be consumed.

We chose the set-back thermostat, which can be programmed to shut off at night and during weekdays. But that feature has yet to be used. This deluxe thermostat costs over $120, and the ordinary unit was (I think) about $50. I would recommend the ordinary thermostat and just keep it at a reasonable setting. Since these cables consume so little power, it might take many years to pay back the difference in energy savings.

Note that this system may not be able to heat the air for an entire room. The room still needs a source of conventional heat, such as a ducted furnace system. I have seen houses that employ in-floor and under-floor hot-water heating that does heat the entire room. The water is heated by a gas-fired boiler, which is much less expensive to run than electric heat.

I would definitely recommend electric floor warming systems to anyone who intends to install a tile floor in a bathroom, kitchen, hallway or anyplace where people may walk with bare feet.


Update: 

It's worth mentioning that a technical representative from Easy Heat contacted us about 3 months after this article was published, asking for feedback on several points. That's a sign of a smart company. It tells me that the people at Easy Heat are searching the World Wide Web for mentions of their product and addressing any concerns the public may have.


Continue To: Laying Floor Tile

 

 

Tools Used:

  • Cordless Drill/Driver
  • Masonry Drill Bits
  • Basic Electrical Tools

Materials Used:

  • Floor Warming Cable Kits
  • Thermostat For Above
  • "Rock-On" Cement Board Screws

 

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Copyright © 2001, 2005 HammerZone.com

Written February 24, 2001
Revised January 11, 2005