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Water heaters that heat?

I have come across 2 water heaters that circulate water to a coil which I am assuming is a radiator. The problem I am having is that the water comes into the coil hot but comes out too cool and is not heating the space. I did bleed all the air out of the lines but still no luck. First questions what is this type of system called? And secondly, what can I do to increase water flow so that it can keep up?


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Sounds pretty strange.

    You have two water heaters supplying water to one coil of some kind? I am not a professional, but am interested in heating things. Are the heaters in series, or in parallel? It must be a pretty large coil. Is there one circulator or two to make the water go through the coil?  In any case, if the water enters that coil hot and comes out cold, the coil is heating all it can. I bet others, as well as I, would like to see pictures of this setup.

    If it really is a problem of insufficient flow, larger diameter pipe, or a pump with greater capacity could increase the flow. But before bothering with this, you will need to find out what the problem is. Did this system ever work?
  • Mr_Apprentice
    Mr_Apprentice Member Posts: 3

    According to the tenant he never used the heater. He only lived there for a short time. I did hear that the coils over time get some type of buildup and restrict flow. Could that possibly be an issue or does that sound like something else.
  • Mr_Apprentice
    Mr_Apprentice Member Posts: 3

    I meant that there are two separate incidents where this problem occured not 2 water heaters in the same space. Sorry.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    More questions.

    I still do not understand your system. Is the water heater to heat the building with a a radiator you call a coil? Or is it there to heat domestic hot water? Is it a closed system?  Or is it an open one? If closed, I doubt you would have deposits clogging your radiator coil. If it is supplying domestic hot water through the coil, it could get clogged after a while, but if the tenant never used the hot water, that is unlikely.

    You still have to describe your system well enough so we who cannot see it, can know hwat you have.
  • meplumber
    meplumber Member Posts: 678
    Not legal in a lot of jurisdictions.

    The use of a domestic water heater that also provides central heating is not allowed in most jurisdictions.  That doesn't mean that we don't all see them.  The problems arise at or near design conditions.  If the design load was based on a water temp higher than the water heater can safely produce, then you have a problem.
  • billtwocase
    billtwocase Member Posts: 2,385
    As Meplumber said

    Potable water heating vessels are not approved for space heating
This discussion has been closed.