Messages and Online Forum Q&A

Re: Electric Radiant Floor Heating

From: info@builderswebsource.com
Category: HVAC
Remote Name: 63.198.181.43
Date: 23 Jun 2001
Time: 10:59 PM

Comments

Electric radiant floor heating based on rolls or mats can be cost-effective for heating small areas such as kitchens and bathrooms. Large areas are better served by forced-air heating or hydronic radiant heating. In theory, electric mats using electric resistance cables should be reliable if properly installed. I am aware of installations that have been running for years without failure. The construction of the resistance cable is as shown here, courtesy Warmly Yours, a supplier of radiant floor heating systems.

However, there is conflicting information about the overall reliability of buried electric cables and mats. The Radiant Heat Institute says, "...we have installed two cable systems and both failed within five years. Electrical resistance cables have an inherent problem of developing hot spots in the wire and burning a hole in the wire. This problem is made worse by voltage fluctuations." Should a break occur in actual service, splicing kits are available to perform repairs. It's always a good idea to keep a few square feet of extra tile or marble just in case a repair has to be made down the road.

Nuheat, a Canadian manufacturer, offers a pro-rated 25-year warranty on its product. Other manufacturers offer 10-year warranties. However, most warranties only cover the cost of the material itself, not the expense of ripping up your tile or marble and repairing it. Furthermore, many warranties are non-transferable to a new owner. As a result, the warranties are almost meaningless since by far the biggest cost is the floor covering itself.

Energy consumption ranges typically from 10-15 watts per square foot. Depending on your electricity rates and overall coverage, operating costs can range from 10-50 cents or more per day for 100 square feet of floor area. Be sure to use a GFCI to prevent shock, as well as a timer (Intermatic) or thermostat to conserve energy such as the one shown here by Warmly Yours. A Canadian energy management products company, Aube Technologies (http://www.aubetech.com), makes a range of quality thermostats with an integrated GFCI specifically for radiant heating systems, including systems with telephone interfaces to allow for "pre-heating" activation by phone. An online source for these controls at good prices is http://www.energyautomationinc.com.

Since electric mats are installed close to the surface of the floor, they can warm up a bathroom in as little as 30 minutes. However, the thermal mass doesn't compare to traditional hydronic radiant heat systems, so the floor will cool off about as fast as it heated up.

For additional information on prices and installation of electric radiant heat systems, see http://www.nuheat.com and http://www.warmlyyours.com.

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