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Need help with indirect DHW

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Comments

  • andycoop
    andycoop Member Posts: 7
    Getting back to this problem. Yes, @HVACNUT you are correct, the bulb was not fully inserted. That was easy to fix with a gentle push with a screwdriver. It is now in as far as it will go. However, it did not bottom out.

    The bulb extends 6 inches, and when I removed the original one, I stuck a 6" screwdriver in the well and it didn't hit the end. So that's the best this will do. Also, there was no grease in there, dried or otherwise.

    After I inserted it, I re-ran my tests.

    Start: water at tap 144 degrees
    Ran water down to 90
    Water heater turned on 7 minutes later.
    Water heater ran for 46 minutes.
    Water temp = 138.
    Hours later the water temp = 154. I assume the water heater ran again.

    A few days later, I did it again.
    Start: water at tap 157 degrees
    Ran water down to 90
    Water heater turned on 1 hour and 17 minutes later.
    Water heater ran for 46 minutes.
    Water temp = 143.

    I'd like to catch it when the water heater turns on without me running it down, but I have to get lucky for that.

    In the meantime, I'm going back to Bradford White on this.

    As always, thanks for everyone's help and expertise on this.

    ~~Andy
  • hot_rod
    hot_rod Member Posts: 23,267
    157 degree hot water at the tap? Yikes be very careful. What temperature do you have the control set at?

    1hour and 17 minute delay to fire when the control has been at 90 degrees? That is a huge thermal lag.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • HVACNUT
    HVACNUT Member Posts: 6,298
    The well is probably packed or has dried grey goo so the bulb can't be fully inserted.
    Get a new well.
    Clean the bulb and do a trial run before you install it. When the bulb is fully seated, mark the capillary with a Sharpie at the opening of the well so when you install the well, then insert the bulb, you'll know when it hits bottom. 

    Larry Weingarten
  • hot_rod
    hot_rod Member Posts: 23,267
    edited January 2023
    If a good portion of the bulb is in contact with the well it should read accurately 

    Strap on aquastat have the same bulb with just a strip of the bulb in contact.

    Maybe replace the well with one that matches the bulb length and reach
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream