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hot_rod Member Posts: 21,835
hot water and recirc lines well insulated? If not, that is where the loss is. Constantly circulating 130- 140 in uninsulated copper 24/7 will add up quickly, from a fuel cost standpoint.

hot rod
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream


  • Wayne Jaffe
    Wayne Jaffe Member Posts: 1

    I have a large house with many bathrooms. I have a hot water recirc. loop with a bronze recirc. pump. My problem is the gas usage during the summer. I have an indirect Ergomax Hot Water heater. The return recirc. water causes the DHW system to call for new boiler water about every 75 minutes even when there's no consumption. During the night when the recirc. loop is closed (I have zone valves which stops the gravity flow), the loss is negligible and there's no boiler call.

    What I'm thinking about doing is adding a direct fired gas hot water heater whereby the inflow is the recirc. loop (along with street water) and the outflow feeds the Indirect so that when there isn't any consumption, the Indirect won't call for boiler water and only the smaller gas using direct hot water heater will fire. In times of large consumption, the temperature in the Indirect will drop causing the boilers to fire to feed the Indirect.

    To further save energy, I'm thinking about letting the boiler have a cold start allowing enough time to reach temperature by adjusting the aquastat on the Indirect to a higher setting.

    I'd appreciate your thoughts...

    Thank you...

    Wayne Jaffe
  • Tony_8
    Tony_8 Member Posts: 608

    Why run it all day ? The std water heater won't save you any money on fuel, you'll just burn it in a different appliance. Put a 15 minute timer in to open the ZV and let the end switch cycle the circulator. If you have more than one location you're currently switching from, wire timers in parallel at each location. A little management will save a lot of money.
  • John Reed
    John Reed Member Posts: 5

    Wayne, does your recirc pump run all the time? If it does, you should have it wired to a line mounted aquastat that only has the pump run when the WELL INSULATED water line temp falls below a given set point, say 100 degrees. When there is no hot water consumption, and with the lines well insulated, the recirc pump and boiler pump will hardly ever run. Hope this helps.
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