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Thread: Gravity-Flow hot water recirc.

  1. #1
    DIY Junior Member
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    Default Gravity-Flow hot water recirc.

    Recently did a kitchen remodel and while the walls were open I piped in a hot water recirculation system. It's 3/4" out of the water heater and into the attic. About half way to the kitchen it branches to the bathrooms (capped, not connected yet) and is reduced to 1/2" for the remaining 20' or so to the kitchen. It then loops under the sink, return on the bottom and is 1/2" line back to the water heater. All pipes are insulated. At the water heater is a Grundfos circulator and flo-check valve (horizontal install) just before the line enters the tank at the bottom drain port (tee'd). It all works fine except it seems to be circulating on its own. The hot water out pipe is always hot and the return line is always warm. I've tested the circulator but waven't wired it up yet so it can't be kicking on. Do I need to bring the hot water out line below the drain level to stop the gravity flow?

    Chuck
    Last edited by chucknewell; 02-22-2005 at 04:31 PM. Reason: Sp.
    Chuck

  2. #2
    In the Trades Gary Swart's Avatar
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    Default

    I could be wrong, but I think you're system is normal. I have a different brand recirculating system and while I've never have check it when it was not plugged in, I think it would circulation some without the pump. You could check with the manufacturer, they probably have a website with a phone number for their tech department.

  3. #3
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    Default Manufacturer. . .

    Gary,
    Thanks for your input, I appreciate the reply. Unfortunately this is a "home brew" system. Since I designed it I'll have to fix it. I know I could put a solenoid valve on the return line to stop the flow, but I'd rather do it passively to keep the system simple.

    Thanks again

    Chuck
    Chuck

  4. #4
    Moderator & Master Plumber hj's Avatar
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    Default circulation

    If it is circulating by convection, what is the problem. It would be more of a problem if you wanted it to circulate and it didn't, which would be the normal situation since a convection system has to be installed to very precise parameters.

  5. #5
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    It's not supposed to be a gravity flow system. I'm in San Diego where energy costs are quite high and I don't want the water heater to cycle unnecessarily. Also, the controls for the pump are three parts: Timer, Open on temperature rise t-stat, and a close on temperature rise t-stat. The timer and open on rise t-stat function as usual. Clock turns on pump, hot water gets to kitchen t-stat opens - pump turns off. The close on rise t-stat is the other reason I need to stop the free flow. The idea is to be able to "turn on" the recirculation system remotely during times when the time clock doesn't have it on. The close on rise t-stat is on the hot water pipe a couple feet from the water heater. So, any hot water faucet in the house becomes a switch to activate the recirculation system. Turn on a hot water faucet for a couple of seconds, the pipe at the water heater fills with hot water, closes the t-stat, pump comes on and sends hot water to all faucets.

    I know this seems like a lot. Mostly it's to save water; my last water bill was $234 for two people living in a 920 sq. ft. house. I hate running water down the drain while waiting for it to get hot.



    Chuck
    Chuck

  6. #6

    Default To circulate or not to circulate

    install heat-trap nipples

  7. #7
    DIY Junior Member
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    Thumbs up

    Nipples are already installed. Thanks any way. I broke down and bought a solenoid valve today. Job done.

    Chuck
    Chuck

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