Convection loop stopped with new water heater install

Discussion in 'Water Heater Forum, Tanks' started by Lee Hagen, Apr 21, 2021.

  1. Lee Hagen

    Lee Hagen New Member

    Joined:
    Apr 21, 2021
    Location:
    Delafield, Wisconsin
    Hi all,

    I posted this in the main forum but just noticed this forum is more appropriate.

    Our convection loop worked fine for the last 25 years and three water heaters (Rheem or Ruud). Installed a new gas Richmond 9G50-38F3 and now its like there's no loop in the system.

    Water heater is installed in basement. Runs about 20 feet to first floor bath. Takes a left turn and runs about 30 ft to a T that goes up stairs. Couple more feet there's another T. Straight goes to a basement bath and the T turns left and ends under the kitchen. I installed a T there, then reduced to 1/2" and it returns to above the heater with an elbow that runs down to the drain on the heater, where I put in another T. The line from the kitchen sink is downhill to the elbow above the tank.

    Water coming out of the tank at the relief valve is 125 degrees after heat cycle ends.

    The return line along side the tank is only 80 degrees. I drained the system and disconnected a valve on the line just above the tank and water is flowing from the kitchen sink. Opened the drain valve on the tank and water flows properly.

    As I mentioned... all this worked fine until installing the new tank. Hot water at the kitchen faucet never seems to get hot. The upstairs shower does get hot.

    Any suggestions?

    Thanks.
     
  2. breplum

    breplum Member

    Joined:
    Oct 2, 2004
    Occupation:
    Plumbing and heating contractor
    Location:
    San Francisco Bay Area
    Likely, the heat trap on the new water heater hot nipple are to blame.
    If you remove the hot side tank nipple and replace with simple brass, see if it gets better.
     
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  4. Lee Hagen

    Lee Hagen New Member

    Joined:
    Apr 21, 2021
    Location:
    Delafield, Wisconsin
    The first bath gets hot water, with a bit of a delay (before the new tank, it was HOT in 3 seconds), as does the upstairs bath (105 deg.), with more of a delay, so hot water is flowing. Why would a brass nipple have an affect? Is there something called a 'heat trap' or are you saying heat is being trapped?

    The kitchen is the main problem (closest to the tank on the return line). Hot never gets hot like it has with the past tanks. I doubt the temp gets above 95 deg.

    Is there a chance that some water is flowing back to the kitchen from drain side of the tank? I read where some have put a check valve in the return line.

    Thanks for replying.
     
  5. Bannerman

    Bannerman Well-Known Member

    Joined:
    Mar 19, 2014
    Location:
    Ontario, Canada
    As breplum said, there is likely a heat trap within the new WH hot nipple. Replacing the exsisting nipple with a plain brass one will eliminate the heat trap so water can then flow from the WH without restriction.
     
  6. Lee Hagen

    Lee Hagen New Member

    Joined:
    Apr 21, 2021
    Location:
    Delafield, Wisconsin
    Never heard of the 'heat trap'. I will pull it out. What's the reason to use brass instead of the standard galvanized?
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Galvanized rusts. However a "dielectric" nipple, which is galvanized lined with plastic, is good enough, and is what is most commonly used.
     
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