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Ground water temp for On-demand hotwater in Alaska

Mytoy6 Member Posts: 19
Any ideas on how to raise the groundwater temp before it enters the on-demand hotwater heater/ boiler(ONEX). My hotwater pressure is low and i think if i can raise the temp of the source water i would get my pressure back with less temp flucuation. I had a friend tell me about a brazed plate heat exchanger run off my boiler as an additional zone might accomplish what i want without a storage tank. Anyone done this? My friend uses it for his hot water but he has a older boiler with much more btu then mine. I would like to keep it efficient as possible, without a storage tank of water.



  • heatpro02920
    heatpro02920 Member Posts: 991
    Which unit

    There are simple ways to raise the temp but which is going to make sense?

    What unit do you have {link me}?

    Natural gas propane?

    What is your incoming temp?

    Most gas tankless units don't like high incoming temps and with a plate exchanger you will get high temps, even if you pipe it on the boiler return {and you need to be careful not to cool the return too much}...

    I am thinking you need a larger tankless unit... its easy to figure out, how many gpm do you use, what is your incoming temp, and what outgoing temp do you want?

    My water comes in around 45* and my tankless is set at 115 in the winter thats a 70 degree delta.... which a larger tankless 199K btu unit should make around 5.5gpm {ru98i}... So even if you come in 33* and wanted 120 an ru98i would give you over 4 gpm.... That's still a lot of hot water, that's a shower and a couple faucets running full hot...

    that may be a better option than preheating the water, plate exchangers aren't the longest lasting pieces of equipment and they aren't real cheap {plus you should get one marked nsf or for potable water, low lead}...

    In my hunting cabin I only have a tiny electric water heater and the incoming water is COLD, so I run the water through a piece of baseboard near the wood stove before it goes to the water heater, it works really good... But when I take heating buddies up hunting, they always ask why I have baseboard 7 feet off the foor....

    Also look into high sierra shower heads, I love these things... they stretch your hot water out a lot...
  • kcopp
    kcopp Member Posts: 4,095
    I have one....

    of these. Its a GFX heat exchanger.

  • SWEI
    SWEI Member Posts: 7,356
    good stuff

    rule #1 for winter heating:  Don't throw away heat you've already paid for.
  • Mytoy6
    Mytoy6 Member Posts: 19
    edited April 2013
    My unit is the Embassy ONEX (NAT GAS)

    The Embassy ONEX boiler I have has a DHW function which runs at 160,000 btu with 4GPH rating and my incoming water temp is around 35.4 to 44.2 during the winter.
  • SWEI
    SWEI Member Posts: 7,356
    You may not like this answer

    but the simplest and least expensive way to solve your problem is to add storage to the system.  An electric tank-type water heater will be cheap and effective.  If you install it in conditioned space, the little bit of energy it loses will just act as a tiny supplement to your space heat.
  • heatpro02920
    heatpro02920 Member Posts: 991
    OK, combi unit

    Im going to have to agree with Swei, add a bronze or ss circulator and an electric water heater, if you have the funds maybe a hybrid water heater and then in the summer turn the boiler off and use the hybrid function.... Always nice to have aux. DHW too...
  • earl burnermann
    earl burnermann Member Posts: 126
    How about...

    Installing the largest electric water heat that will fit in your conditioned space. Do not hook it up. Remove the insulation from the new electric water heater and have this unit feed your cold water feed. Let the conditioned space heat the tank.
    If the women don't find you handsome, they should at least find you handy!
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