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W/M Plus 100 question

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Phil_6
Phil_6 Member Posts: 210
I just took over a job to finish where they have a Weil Mc Lain Plus 100 indirect water heater connected to the boiler. I usually don't use this brand of water heater, but it seems to work great except for the water temperature of the domestic water shoots way up to 170-180 degrees no matter what the thermostat on the tank is set at. The piping and wiring is all pretty straight forward, heater is wired to an Argo relay which starts the circ and boiler. I changed the thermostat assembly like the Weil McLain tech guy suggested but I guess he was wrong. Still happens. Any suggestions?

Thanks, Phil

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  • Big Idahoan
    Big Idahoan Member Posts: 43
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    inderect check

    have you checked the piping? are you getting unwanted heat migration through the inderect water heater loop? is there flow checks installed on the supply and return lines.
  • hydronicsmike
    hydronicsmike Member Posts: 855
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    wiring?

    If you checked the above:

    Something could be wired funny, or the Relay is shot - causing the pump and boiler to stay on even though the aquastat is satisfied.

    Check the wiring and relay. You may have some backfeeding going on there.

    Mike
  • Phil_6
    Phil_6 Member Posts: 210
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    wiring

    every thing appears as it should be. I can stand right there and watch it shoot right to 170 or so and the relay shuts off.The thermostat on the water heater clicks the relay right on and off. Just not at a low enough temp.
  • [Deleted User]
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    Check for a

    properly sized pump for the tank. The +100 needs 22 gpm @ approx 2' of head. That means 1 1/2" pipe. Can't cheat on this puppy. Funny things will happen.
  • Al Letellier
    Al Letellier Member Posts: 781
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    PLUS 100

    > I just took over a job to finish where they have

    > a Weil Mc Lain Plus 100 indirect water heater

    > connected to the boiler. I usually don't use this

    > brand of water heater, but it seems to work great

    > except for the water temperature of the domestic

    > water shoots way up to 170-180 degrees no matter

    > what the thermostat on the tank is set at. The

    > piping and wiring is all pretty straight forward,

    > heater is wired to an Argo relay which starts the

    > circ and boiler. I changed the thermostat

    > assembly like the Weil McLain tech guy suggested

    > but I guess he was wrong. Still happens. Any

    > suggestions?

    >

    > Thanks, Phil





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  • Al Letellier
    Al Letellier Member Posts: 781
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    PLUS 100

    i install a lot of these tanks and they all seem to stack a lot of temp. I certainly hope you have a good mixer on that hot water line.

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  • paul sr
    paul sr Member Posts: 39
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    I HAVE PUT IN MANY +40'S AND HAVE HAD SERVICE CALLS ON +100'S. MY GUESS IS MAYBE THE FLOWCHECK OR ZONE VALVE (EITHER/OR) ISNT CLOSING FULLY, OR MAYBE THAT EXTRA DIP TUBE THAT COMES WITH IT MIGHT HAVE BEEN PUT IN THE HOT SIDE BY ACCIDENT. AND MAY NOT HAVE ONE ON THE COLD SIDE ( IVE SEEN SOME REAL BEAUTS) HOPE THIS HELPS
  • Phil_6
    Phil_6 Member Posts: 210
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    Thanks

    Some one else installed this equipment. Judging from the sloppy work around the house, anything is possible. I think I'm going to tell the cust we need to disconnect it, inspect it and re-install it with a mixing valve. I hope they'll go for it.

    Phil
This discussion has been closed.