Radiant heating: Pros and cons of heating your bathroom floor

Radiant heating: Pros and cons of heating your bathroom floor
Radiant flooring adds a cozy feature to this already stunning bathroom. (Photo courtesy of Angie’s List member Bob K. of Flemington, N.J.)

Radiant flooring adds a cozy feature to this already stunning bathroom. (Photo courtesy of Angie’s List member Bob K. of Flemington, N.J.)

Radiant heating, also known as radiant floor heating (RFH), has been used since the days of ancient Rome to heat spaces effectively with minimal energy loss. In many parts of Europe, this is the preferred method of room heating, and in the United States RFH is quickly becoming a popular home remodeling option. Here are the top pros and cons of installing a radiant floor system in your bathroom.

Pro: Smooth heat

A radiant heat system uses a series of hot water tubes or wires under the floor to produce a smooth, even heat. Unlike a forced air furnace, which quickly pushes hot air up through vents toward the ceiling, an in-floor system heats slowly over its entire surface. This prevents the problem of a "cold 70," a term coined by heating expert Richard Trethewey of This Old House, which describes the phenomenon of furnace air quickly ramping up a room to 70 degrees and then shutting off, leaving comfortable air near the ceiling but cold air at your feet. By radiating heat over an entire floor, heat not only spreads evenly but objects in a room also heat up slowly, releasing more warmth.

This type of heat is a good choice for a bathroom because it works well with linoleum, laminate or tile flooring. Expect approximately an hour for your floor and the surrounding air to heat up when using an RFH system. In addition to consistent, comfortable heat and cost savings over time, RFH installations in your bathroom also cut down on noise. With no furnace to cut in, there are no ducts to rattle or loose vents to shake or squeak. In addition, these systems can last up to 40 years before needing replacement, instead of the typical 10 or 15 offered by a traditional furnace.

Con: Some assembly required

Laying an electric RFH system requires tearing up the existing floor, laying down wire mats and then replacing the floor. Experienced home handymen may be able to tackle this job themselves, but it can be time consuming. A hydronic system, meanwhile, requires not only a significant time investment, but an experienced contractor. Because hydronic systems work best when they have a thermal mass, a pad of concrete is often placed underneath them, or a thin layer of concrete is placed between the heating tubes and the floor. Properly pouring this concrete, especially in a main level or second-floor bathroom, is a difficult undertaking.

Pro: Different heating types

You can install either of two types of RFH: hydronic systems and electric radiant floors. Hydronic systems use polyethylene tubing buried beneath the floor, which carries hot water pumped through it to create heat. Although more expensive than a forced air furnace initially, this type of heating can significantly reduce energy costs over time. This type of heating is suitable for anywhere in a home, including a bathroom. Electric radiant floors also work well in a bathroom but are typically too expensive for all floors in a house. This type of RFH uses heat-conducting plastic mats, which contain copper or nichrome resistance wires.

Con: Potential floor damage

Both types of RHF pose the risk of damage to your floor, either through a ruptured water tube or fire due to a faulty resistance wire. Both are unlikely circumstances: Polyethylene tubes (unlike traditional copper) are resistant to corrosion, and electrical systems use a slow and low method to heat your floor, rather than quick, high-powered bursts. You can make minor repairs on electrical systems yourself, but troubleshooting a hydronic system requires a professional contractor. Improper installation could lead to excessive heat and, in turn, significant damage or risk, especially around tubs, toilets or shower enclosures.

Although more expensive upfront than a forced air furnace — at least $2,000 for an electric system in a bathroom and $15,000 for a hydronic boiler — the cost savings over time combined with slow, even heating make RFH choices a solid investment for any bathroom. Significant installation requirements and the possibility of a in-floor damage, however, are also important to consider before making a switch.


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Comments

Does anybody actually still make and install electric resistance coils for subfloor heating? I thought that dinosaur finally went extinct. It was always subject to hot spots, required a specialist for installation, and there was (as your consultant says) always a danger of an electrical fire from an arc. The hydronic system is much more reliable, energy-efficient, and easily repaired. If the correct type of water line is used, it will not break under normal pressures and is usually only heated to about 110 to 120 degrees... about the same as the hottest setting on your shower. They do work best when installed between a concrete slab and a tile or hardwood floor, as carpet reduces the heat transmission into the room above. Most homeowners should get some professional advice from a consulting engineer (NOT from a plumbing contractor, with all due respect) before making the decision to retrofit an existing home with this system. If it's not designed AND installed correctly, it's a major headache instead of a high-comfort money saver.

Doing a retro on radiant heating may not be worth the effort or expense. For new construction, the added cost, and zone capability, makes radiant heat the savior of indoor heating. A good layout covers the floor and even warmth is guaranteed. The new piping is great, and well worth the investment.

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