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-   -   Very little hot water (https://www.askmehelpdesk.com/showthread.php?t=89693)

  • May 6, 2007, 08:58 AM
    kcoryer916
    Very little hot water
    Trying to figure out why the hot water comes out of the taps scalding hot for about two minutes and lukewarm at best after that. After some research I decided it was the tempering valve. When I went to look I could not find one. We have a tankless hot water boiler, HB Smith FD12-W-5. I found the manual and there IS one in the diagram but like I said for the life of me I cannot see it. Can I install one if it's not there. If the tempering valve is not the problem what else should I be looking at? Thanks in advance for you help.
  • May 6, 2007, 04:30 PM
    hvac1000
    Possible scale in the heat exchanger.
  • May 6, 2007, 05:00 PM
    JackT
    How old is your boiler? If you have a tempering valve, I don't believe that's your problem. I agree with hvac1000 that you probably have a scale problem in your heat exchanger. Over a period your heat exchanger will build up a white scale on the inside of the pipes. This scale acts as an insulator slowing down the process of heating up the water. The water that's just sitting in the exchanger is hot but, as soon as you open up your faucet, the boiler can't heat up the cold water fast enough and as a result you'll get only warm water. Depending on the age and condition, you may find someone who can circulate acid cleaner through it that will remove the scale. Or it may have to be replaced.
  • May 6, 2007, 05:46 PM
    kcoryer916
    Quote:
    Originally Posted by kcoryer916
    Trying to figure out why the hot water comes out of the taps scalding hot for about two minutes and lukewarm at best after that. After some research I decided it was the tempering valve. When I went to look I could not find one. We have a tankless hot water boiler, HB Smith FD12-W-5. I found the manual and there IS one in the diagram but like I said for the life of me I cannot see it. Can I install one if it's not there. If the tempering valve is not the problem what else should I be looking at? Thanks in advance for you help.
    The boiler was installed in 88' so maybe it is time for a new exchanger. Thanks.
  • May 7, 2007, 04:22 AM
    labman
    So much for the supposed longer life of the tankless heaters.
  • May 7, 2007, 04:25 AM
    hvac1000
    Here is a web site for your replacement coil.

    HB Smith - Tankless Heaters Replacement Coils

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