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Hot Water Recirculation System

  • Transcript

    LESLIE: Well, when most of us awake and head for a hot shower to get the blood flowing, we often have to wait and then sometimes wait and wait and wait for the water that runs through the shower to actually get hot.

    TOM: Absolutely. And besides testing your patience and having to run all that cold water through your pipes to just get the hot water, well, it’s not a very environmentally-friendly thing to do. One solution, though, is to install a hot-water recirculation system. Here to tell us more about that option is a guy who gets more homeowners into hot water than out of it – and that’s a good thing – This Old House plumbing expert, Richard Trethewey.

    Hi, Richard.

    RICHARD: Hi, guys. Nice to be here.

    TOM: And this is a question we get asked very, very frequently on the show and most people think that a new water heater will solve this problem but it’s really not a case of capacity, is it?

    RICHARD: Well, think about it. If your master bathroom is 60 feet away from the water heater, you have to open up your hot-water faucet and 60-feet-worth of water has to be emptied out of that pipe before you see some of the hot water.

    So what we’ve often seen is people put in a hot-water recirculation system. This is a little, bronze pump that would come on at specified times and it would bring that hot water up towards that fixture – the farthest-away fixture from the water heater – so you can open up your faucet and have hot water right then.

    LESLIE: Now, does that require any extra plumbing, like perhaps a loop to sort of keep that water going to that fixture? So is that something that can be done in a retrofit?

    RICHARD: Well, there’s two choices. If you have a wide-open basement, then you can do it. You can run a relatively small – just a ½-inch – line from that farthest fixture back to the water heater, with a little, bronze pump and a little check valve and usually a timer. Now, sometimes you can’t, as you note, in a retrofit.

    And they also make this very ingenious, little, bronze pump that can sit underneath a vanity in your master bathroom. And you can hit a button and it can bring on a little pump which pulls the water from the hot-water pipe and actually pushes it over towards the cold-water pipe. And so – and it’ll shut off as soon as the hot water gets to that little pump. And there you open up the faucet, you’ve wasted no water and it’s coming on when you need it and only when you need it.

    LESLIE: Is that terribly expensive to operate?

    RICHARD: No, it’s actually – it’s more efficient to operate than a conventional recirc line. If you have a conventional recirc line, it actually can be an energy waster and let me explain. If it’s on all the time and you have a water heater that’s sitting at 130 or 140-degree water and you’re just pulling that hot water out and circulating into the far end of the building and coming back, you’re bringing cooler water back and making the water heater work harder. So, it’s a pretty good energy waster if it’s not properly controlled.

    This device I was talking about up underneath the vanity, you hit a button when you’re in the bathroom and bring it on and so you’re really not going to have that waste of energy.

    TOM: And the time it takes for that water to get warm once you bring it on?

    RICHARD: It’s a function of the distance away, you know. But it’s not much; it’s a couple seconds I think, yeah.

    TOM: Right. And certainly not nearly as much wasted water.

    RICHARD: That’s right.

    TOM: And as you say, the water heater is not sitting there reheating water that’s cold; excessively so.

    RICHARD: Right.

    TOM: Because I think we don’t realize that water heaters are pretty dumb.

    RICHARD: Right.

    TOM: I mean they’re designed to keep water in that vessel at 110 degrees, 24-7, so the more cold water you dump in there, the more gas that has to come, the more electricity has to run.

    RICHARD: That’s right. I think I saw the future, recently, in Europe. I was at a place that sort of has the new energy model over there and it had a little proximity switch when you walked into the bedroom – sorry – the bathroom. And so, when you came into the bathroom, the recirc pump came on then and only then.

    TOM: Oh, like an occupancy sensor?

    LESLIE: Yeah, that’s cool.

    RICHARD: Absolutely.

    TOM: Oh, cool.

    RICHARD: So it just brought that pump on just then because otherwise, people will leave the timer on all day and then they’ll be at work and they’re wasting energy.

    TOM: Right. I can barely get the kids to shut the faucet off, let alone the little button under the vanity.

    RICHARD: That’s right.

    TOM: Well, what a fantastic system. For more tips just like that, from Richard and the entire This Old House team, check out ThisOldHouse.com.

    Richard, thanks so much for stopping by The Money Pit. You’re going to make us a lot more comfortable in the morning.

    RICHARD: Great to be here.

    LESLIE: Alright. For more great home improvement advice, you can watch Richard and the entire This Old House team on This Old House and Ask This Old House on your local PBS station.

    TOM: And Ask This Old House is brought to you by GMC. GMC, we are professional grade.

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