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Quick Informal Survey - Indirect DHW or Not

KevinWyman
KevinWyman Member Posts: 35
in THE MAIN WALL
Look at the attached file and please try to classify the domestic hot water system in the picture.



Would you say it is an indirect DHW (albeit with a very, very small tank)?

Some other type of system not yet named?



(Inside the Slant-Fin Combi-Cat is a brazed heat exchanger as well as a pump and flow switch).

Thanks for playing!

Comments

  • Brad White
    Brad White Member Posts: 2,399
    I would

    call it an indirect, as defined by having no combustion, relying on an outside heating source. The volume would not matter. Even a BPX as an instantaneous heater would qualify as an indirect, at least by my definition.



    My $0.02 anyway.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    It's an indirect, instantaneous hot water heater

    I'd be interested to know how instant this instantaneous hwh is in the summer. 



    The most common issue with the currently trendy crop of instantaneous water heaters is time delay from when the tap is turned on(call for hot water) to when the heater delivers acceptably hot water.  The fix from the sales guys is to ditch the old school name and start calling them "Tank-less Water Heaters".



    The good ol' Bosch WR400-1k had a standing pilot, and was very quick to deliver hot water (+/- 5 secs)



      This unit would be fast when the system is running, but you'd have to keep the boiler hot all summer to avoid waiting over a minite for the boiler to get up to heat.  I don't think I'd be reccomending it for a residential application.

    There was an error rendering this rich post.

  • icesailor
    icesailor Member Posts: 7,265
    Indirect or not:

    I call it a "Tankless" (indirect) hot water heater. Whether the HX is in the boiler water or you pump the boiler water through the HX, it's a "Tankless Heater".

    A properly piped storage tank will solve any inherent problems with the operations. Piped the way "I" do them.
  • icesailor
    icesailor Member Posts: 7,265
    Indirect or not:

    I call it a "Tankless" (indirect) hot water heater. Whether the HX is in the boiler water or you pump the boiler water through the HX, it's a "Tankless Heater".

    A properly piped storage tank will solve any inherent problems with the operations. Piped the way "I" do them.
  • KevinWyman
    KevinWyman Member Posts: 35
    Summer Operation

    Time will tell on the summer operation. Perhaps the hot water setpoint  temperature will need to be increased although so far throughout the winter, there have been many times when the boiler was cold (not delivering heating hot water) and the unit fired up and provided the hot water to the DHW heat exchanger very quickly. With small boiler capacity, small loop capacity and tight heat exchanger "pinch" that is to be expected.

     With these types of systems there is that slug of cold water that travels ahead of the arriving hot water. Not too big of an issue so far. This was true of the gas hot water tank it replaced as well frankly for most situations.  Certainly balanced by the long run time of hot water (as my teenage daughters will attest to). There certainly is no tank-loss with this type of indirect. Tankless Indirect.
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