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Adding Radiant Heat to Your Floor

  • Transcript

    LESLIE: Well, for many, one of the most unpleasant steps you can take in your home is by setting foot on a cold floor with bare feet.

    TOM: So true. And that’s just one of the reasons adding radiant heat to your floor is a great idea. Not only does it stop that toe shock, it can actually make your entire home more comfortable and cut down on your energy bills. Here to tell us more about radiant heat is Richard Trethewey, the plumbing and heating contractor from TV’s This Old House.

    Welcome, Richard.

    RICHARD: Glad to be here.

    TOM: Now, this is a project that can be done from above or below the floor, right?

    RICHARD: That’s right. It can be installed from below the subfloor or above if the area below is difficult to access.

    TOM: Now, let’s talk about the types of radiant heat. The one that you most commonly work with is hydronic heat, correct?

    RICHARD: Right. That’s a fancy word that people don’t understand; they think it’s hydraulic, hydronic, hydroponic.

    LESLIE: Yeah.

    RICHARD: But it’s really just the use of warm water to circulate through pipes and the other is electric.

    TOM: Now, how does the hydronic heat work? Is it run through special types of pipes?

    RICHARD: What you really want is you want to have these veins running through your building that are going to last. And so the plastic pipe of choice is called PEX – P-E-X. And that can be installed a couple of different ways. It can go from below the subfloor; it can be sandwiched in between the subfloor and the finished floor, as well.

    TOM: Now, I’ve seen you, on the show, use something that looks like sort of grooved-out plywood boards that’s made for the radiant heat to fit right in. And can you talk about that?

    RICHARD: That’s right. It’s that sandwich I was just talking about where you’ve got your plywood subfloor and you put down these plywood strips that have aluminum attached to the back side. It has a perfect groove in it to allow you to put the tubing right into it. It has a place for the tubing to return back and forth, so you have a serpentine pattern of radiant heating in your kitchen. And then you put your finished floor down over the top of it.

    The key on that is to make sure you don’t put the radiant underneath your kitchen cabinets, don’t put it under the island. It’ll make the potatoes grow like a weed.

    LESLIE: Now, are there better flooring choices that work more in partnership with a radiant floor?

    RICHARD: Well, everybody has to understand that the more you put in terms of R-value on top of the floor, the hotter the water and the hotter it is to send the energy up into the room. So tile or marble or stone is the greatest because it just gives off its heat so readily. And then – but some people want to put wood floors on; that’s fine. With any solid hardwood, you’ve got to be sure you get the moisture level correct. I’m particularly a fan of prefinished wood, which is – it really comes out of a box and just clips together and it’s – it doesn’t have any issues.

    TOM: Like engineered hardwood, for example.

    RICHARD: Absolutely. And it works great and it’s perfect for radiant. And you can do carpet but you have to find a place where you can live with a carpet that doesn’t have too high of an R-value and too thick of a pad. Because if it is, you’re just defeating the purpose already.

    LESLIE: You’re not even going to feel it.

    RICHARD: That’s right.

    TOM: We’re talking to Richard Trethewey. He is the plumbing and heating contractor from TV’s This Old House.

    Richard, let’s talk about that radiant electric heat. Now, that’s something that’s typically used in the kitchen or the bathroom. Good application for those small rooms, especially?

    RICHARD: Well, it’s such a great sort of way to chase the chill off of a room. I don’t think I would always use it in our particularly cold climate; we’re based in the Northeast here. I might use electricity just as a backup to sort of chase the chill off the tile. But in marginal climates, it could be the principal way you heat the building and there’s nothing better. And you can put it in floors, you can put it in walls of shower stalls. You really don’t think one-dimensionally; you can put it in a lot of different places.

    LESLIE: Now, Richard, how efficient is radiant heat? I mean are you really going to save a lot of money if this is your primary heat source?

    RICHARD: Simply put, there is no more efficient way to heat the human body than radiant heating.

    TOM: Wow.

    RICHARD: You put it into a floor, you stand on it. You have warm feet and a cool head. As the heat heats the person, it gets cooler as you go to the top of the room. Now, at the top of the room, that’s where most heat loss happens. So if you have less heat at the top of the room, less heat leaves the building. And you’re only circulating warm water; you’re putting 95- to 105-degree water where most baseboard or radiator jobs need 180 or 200 degrees. No better way to heat and no more efficient way to do it.

    TOM: So you’re wishing us warm feet and a cool head always in life.

    RICHARD: That’s right.

    TOM: That’s a great thing to live by. Richard Trethewey from TV’s This Old House, thanks so much for stopping by The Money Pit and filling us in on the warmth of radiant heat.

    LESLIE: You can catch the current season of This Old House and Ask This Old House on PBS. For local listings and step-by-step videos on radiant heat and other projects, visit ThisOldHouse.com.

    TOM: And Ask This Old House is brought to you by Stanley. Stanley, make something great.

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