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Thread: Heating coil

  1. #1
    Join Date
    Dec 2011
    Location
    San Diego ca
    Posts
    4

    Confused Heating coil

    This is an interesting set up!! The apartment heater is fed from the water heater with recirculating domestic hot water. Basically a heating coil you would see on any hot water heating system. I'm having issues getting hot water through the coil. It's coming in hot and cools off about 20 degrees on the leaving side of the coil with the fan off. I have bled the system a bit and seem to have good pressure on the leaving side but I know it could be pressurized from return side. Ofcourse the valves are frozen and unable to shut off. Any ideas on how to make my customer happy?!?!

  2. #2
    Join Date
    Feb 2010
    Location
    Landis North Carolina
    Posts
    528
    Quote Originally Posted by Stevo120 View Post
    This is an interesting set up!! The apartment heater is fed from the water heater with recirculating domestic hot water. Basically a heating coil you would see on any hot water heating system. I'm having issues getting hot water through the coil. It's coming in hot and cools off about 20 degrees on the leaving side of the coil with the fan off. I have bled the system a bit and seem to have good pressure on the leaving side but I know it could be pressurized from return side. Ofcourse the valves are frozen and unable to shut off. Any ideas on how to make my customer happy?!?!
    Ive dealt with those.Also it should have a pump,problably inside the air handler.Make shure its working and pumping good.Its a direct drive pump and thats the only moving part to the system.What kind of valves does it have?If they are gate valves,if so verify they are open completly.On gate valves the gate can break loose from the shaft and fall closed or even partially closed.You may need to open the system to make shure you have no excessive pressure drop accross valves after you verify the pump is running.They are really effective and relaively cheap to operate.The only moving parts are the pump and the blower.Really simple and effective

  3. #3
    Join Date
    Mar 2004
    Location
    Chester County PA
    Posts
    371
    Sounds like you only have 2 areas to troubleshoot, hand valves and circulating pump. If it's recirculating the domestic hot water from the water heater tank then you won't have higher return pressure to worry about. It will be equal pressure.

    I would bet money that there's something wrong with the circulating pump, either control side, motor or impeller.
    You should also offer to replace those seized hand valves.

    ~smoke~
    "That motor's done, he let the factory smoke charge out!"

  4. #4
    Join Date
    Feb 2010
    Location
    Landis North Carolina
    Posts
    528
    Echo in here

  5. #5
    Join Date
    Dec 2011
    Location
    San Diego ca
    Posts
    4
    Thanks for the reply guys!! The info is useful!! But to reply to you, I know the pump is working, how well who knows!! But I am getting hot water to about half of the coil. So without having to cut supply and return pipe to blow out the system is my best bet to shut off return and try to blast the coil. I'm afraid the scale may be really built up. So with that in mind any ideas on how to safely treat the coil for scale build up on the domestic hot water side. Remember it's drinking water along with heating.

  6. #6
    Join Date
    Apr 2001
    Location
    Over Here
    Posts
    1,105
    Is this a First Co unit? The check valve may be stuck. The coil discharge, if TEE'd into the tank drain, may be plugged with sediment at the bottom, not allowing flow. You really need operable shut-off valves.

  7. #7
    Join Date
    Dec 2011
    Location
    San Diego ca
    Posts
    4
    Thank you! I will check all those things!!

  8. #8
    Join Date
    Jun 2010
    Location
    Philadelphia PA
    Posts
    2,190

    Hey Steve

    You should check the system design, because if the hot water coil circuit is allowed to stagnate, then you could be growing bugs when space heat not calling. that run should be cut off and drained IMO And I think there is a code thing about that, need to look
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

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