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Thread: Recirculating Hot Water Question

  1. #1
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    Recirculating Hot Water Question

    One of the neatest features about the house we just bought is the recirculating hot water system. The two bathrooms are quite far from the water heater, and it has been awesome to turn on the tap and get nearly instant hot water. That is, until it stopped working yesterday. All of a sudden, the hot water is not instant. Here is the system we have:

    http://www.homedepot.com/p/Watts-Hot...0800/100426993

    According to the previous owner, the pump is just one year old. I can put my hand on the pump and feel the motor running. The whole unit is hot, but that doesn't seem surprising, considering it's on top of the water heater and attached to the outflow line. The only thing I can think of that might have caused things to stop working is the fact that I turned off the water supply to the house yesterday to replace a bathroom faucet. (The cold water valve under the sink in that bathroom is frozen open, so it was easier to simply shut off the whole house.) I didn't think to turn off the pump when I shut off the water. Is there a chance that the pump burned up trying to pump with no water pressure?

    Any other ideas what might be wrong?
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  2. #2
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    Any chance there is an air lock in the system that you need to purge?
    http://media.wattswater.com/IS-IHWRS.pdf

  3. #3
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    That was my thought, you may have an air lock in the system.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  4. #4
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    I'm pretty ignorant about air locks. How does one go about purging the line? Is it these steps (from the troubleshooting section of the manual)?

    If there is no hot water at the faucet or there appears to be too much hot water on the cold water side the following steps will determine if the valve is operating correctly:

    1. Close the cold water stop valve below the sink.

    2. Open the cold water faucet.

    3. Water should slowly flow from the faucet until hot water reaches the valve. The flow should gradually decrease until no water is coming from the faucet at which time the valve is closed.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  5. #5
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    I don't know the exact procedure for your system, but you'll probably want to purge air on both sides of your system, the feed side and return side, so you'd need to open a valve at each end to be sure the return side isn't full of air.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  6. #6
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    Check the installation instructions and pretend its a new installation. Step 6 talks about purging the line.

  7. #7
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    I put a circulating system in my house. The return lines can be fairly small - just enough to keep the water in the pipe warm - the size of ice-maker lines is fine. Those lines ran through my attic. We had a cold winter, and the return lines froze and burst. We have lots of new plaster and paint and no recirculating hot water.

    But now that I have your sympathy, my BIL put a system in his house with a timer. Whenever you walk into the bathroom push the button, and the water recirculates for 15-20 minutes. If you are using it, you don't need recirculation to keep the water hot, but it doesn't circulate 24/7 heating the attic or slab. He says it saves a fortune in water heating cost.
    Charlie Plesums, Austin Texas
    (Retired early to become a custom furnituremaker)
    Lots of my free advice at www.solowoodworker.com

  8. #8
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    Quote Originally Posted by Ted Calver View Post
    Check the installation instructions and pretend its a new installation. Step 6 talks about purging the line.
    Thanks, Ted. I read the steps a few times, but obviously was not really paying attention.

    Quote Originally Posted by Charlie Plesums View Post
    I put a circulating system in my house. The return lines can be fairly small - just enough to keep the water in the pipe warm - the size of ice-maker lines is fine. Those lines ran through my attic. We had a cold winter, and the return lines froze and burst. We have lots of new plaster and paint and no recirculating hot water...
    Charlie, this system uses the existing cold water line as the return.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  9. #9
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    Quote Originally Posted by Vaughn McMillan View Post
    Charlie, this system uses the existing cold water line as the return.

    If the pump is in the bathroom, that makes sense, even though it means that you will have warm water coming from the cold faucets.

    If the pump is at the water tank, the return water goes into the cold side of the hot water tank so that it is reheated - the amount coming out of the hot side of the tank is the same amount that you are returning to the cold side of the tank, so virtually none of the warm water gets into the cold water system (virtually adjusted for the expansion of the water when it is heated, which is VERY small.) When you are drawing hot water, more cold water enters the hot water tank, "flushing" the returning warm water into the tank. Bottom line, if the pump is at the tank, a separate return line comes from the bathroom, and virtually none of the warm water gets into the cold water system. There should be a check valve near the pump so that if the pump stops, the cold water cannot take a shortcut to the hot faucet in the bathroom, going backwards through the return line.
    Charlie Plesums, Austin Texas
    (Retired early to become a custom furnituremaker)
    Lots of my free advice at www.solowoodworker.com

  10. #10
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    Recirculating Hot Water Question

    Charlie, read the manual Ted linked to upthread. The pump is at the water heater and there is no separate return line. Not exactly sure how it all works, but I do know that it did work (remarkably well) before I shut off all the water to the house for a few hours.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

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