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Radiant Floor Heating Installation


July/August 2000
Bill Burns

This is a short picturebook story of a successful tubing radiant floor heating installation.  Thermostat and tubing provided by WarmFloorCenter.com.  They had the best price anywhere I could find complete with prompt and friendly service.

After the subfloor was fastened down, felt and metal lathe was stapled to that with a normal staple gun and staples.  The tubing was then unboxed and we started coming up with a game plan on how to lay it out.  The middle of the room was chosen beforehand as a discrete place to locate the thermostat.

To be honest, we didn't have any idea how to layout the tubing around things like islands, narrow walkways and such.  The installation guide called for a 6.125 inch spacing between tubings for the size of our room and length of tubing provided.  We create a "measuring stick" out of thin wood stock that had marks every 6.125 inches.  This was our template for spacing out the tubings.

The next task was to find a way to fasten the tubing to the floor as we moved along during the installation.  The best option we found was to use a nifty stapler from Arrow that was designed specifically for stapling round tubings down.  It used plastic-coated staples that "hug" the tubing into place without damaging them like all-metal staples would.  Click here for a picture of the supplies we used.

Stapler: Arrow T59-P tacker
Staples: Arrow #591188BL insulated cable staples (1/4" x 1/4") and Arrow #591189BL insulated cable staples (5/16" x 5/16")
As we started laying the cable down, we didn't know if we would run out of cable or have too much left over as we got back to the starting point.  For some reason (and we pretty much attribute it to Good Luck) we had just enough cable as we made the last turn and ran the cable back up into the conduit for the finish.

Remember to not put down cable where things will be permanently placed on top of the finished floor: cabinets, refridgerators, ovens, etc.
Make sure to do the electrical measurements on the card supplied with the cable.  It will help you ensure that the cable arrived in transit intact and that you didn't damage the cable during the stapling process nor the mortar bed process.  (It also ensures that your cable warranty will be valid.)

Remember that we'd never done this before and had no assistance from anyone on how to layout the cable.

Total installation time: it took 2 people 6 hours for a 300 square foot kitchen and dining room with an island and peninsula (250 square foot of actual floor space; 210 sq. feet heated).

The next morning we poured a self-levelling thinset mortar bed made of "Flowcrete" on top of the cables.  The floor was hard enough to walk on within 4 hours.  We let the floor dry for two weeks (it was 90° plus most of that time!) before starting on the ceramic tile installation.

And here's picture of the finished kitchen with the ceramic tile laid on top.  A total of 5 weeks elapsed since mortar bed installation until we turned on the power to the heating cable.  It worked!!!

Our cable is using 220V AC at 10 amps (i.e. 2 kilowatts).  The price for our electricity is about $0.21/kWh.  This means it will cost about $0.40/hour to heat the floor.  Good thing it's on a setback termostat!  The floor has a wonderful warm feel to it when it's being heated, and the heat rises gently above the floor, too -- it's really nice.  Can't wait to use it more often in the winter!

And here's a picture of the finished kitchen, just before we hooked up the thermostat (we took one last measurement before turning on the power).  You can't see the floor heating system at all; it's completed hidden, just waiting to quietly surprise you with warmed tiles.

PEX Tubing, Taco Circulator Pumps, Takagi Tankless Water Heaters