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Tankless Water Heater: Water Not Getting Hot

  • Transcript

    LESLIE: Bobby in Wasilla, Alaska, you’ve got The Money Pit. What can we do for you today?

    BOBBY: Hi. I have a second home that I visit on weekends and I installed an on-demand hot water heater in that cabin. My problem is that the water comes out of the ground at 36 degrees and it doesn’t seem to heat up or it takes a tremendously long time to go through the system for me to get hot water out of the faucet. Is there a way that I could make this a little bit more energy-efficient so it wouldn’t take so long to do that or do I just have to live with it and it’s better than paying for heating water when I’m not there?

    TOM: So it’s a tankless water heater that you have, Bobby?

    BOBBY: It is.

    TOM: Well, that was the right thing to do. Now, usually the cold water problem is a function of the distance between the water heater and the faucet itself because the water has to travel that distance. So, are they at opposite ends of the building?

    BOBBY: They’re on opposite ends of the building but it’s a relatively small building; it’s 24×30.

    TOM: Yeah.

    BOBBY: But I think the issue is that the water coming out of the well is 36 degrees.

    TOM: Well, I would also double-check, though, that the water heater was properly installed. Sometimes, typically what happens is they use a too-small – plumbers use too small of a gas line. Most tankless units, you need a one-inch gas line; not a three-quarter, which is standard for tank water heaters. And so, if it’s not firing completely, that could be the problem. I mean conceptually, that 36 degree water, once it hits the tankless water heater, should come out the other end at 110 degrees.

    LESLIE: The desired temp.

    TOM: At whatever you set it at. It doesn’t have to recirculate to get hot; it just hits it, it gets hot and then it gets delivered. And then there is some time between – to cover the time it takes for the water to get from the water heater to the faucet. But if it’s not coming out the other end of the water heater hot enough, then there may be a problem with the water heater and I – and the most likely culprit would be an undersized gas line.

    BOBBY: That’s terrific. Thank you very much. I’ll check on that.

    TOM: You’re welcome, Bobby. Thanks so much for calling us at 1-888-MONEY-PIT.

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