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Lochinvar Noble DHW piping

Alan (California Radiant) Forbes
Alan (California Radiant) Forbes Member Posts: 4,039
edited June 2020 in THE MAIN WALL
I've got some questions about Lochinvar's recommended piping for DHW recirculation systems.

The first diagram below is a "dedicated return" piping method and the second is a "return through cold line" method from their installation manual.

The dedicated return method seems like a lot of work with no obvious advantage.

Then, there's the requirement of an aquastat to turn off the recirc. pump once the water is hot to "prevent injury or death due to scalding". How does that happen with an anti-scald mixing device?

Lastly, they show a tridicator on the mixed, anti-scald device. I can understand a thermometer, but do you really need to know the pressure on a DHW line?

8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab


  • plumbworker
    plumbworker Member Posts: 2
    Hey Alan, I’d say the piping of the recirc loop is dependent of the type of mixing valve to be installed. Most of the 1017 thermo valves do not have full hot water port shutoff capability hence the split return piping with bypass to prevent temperature creep during non draw periods “circ pump running only”.

    the lower diagram with the return straight back into the cold with no bypass would be acceptable with a valve that has full hot port shut off. To prevent the creep.
  • hot_rod
    hot_rod Member Posts: 22,251
    Here is a winner of a valve that will prevent temperature creep without a need for that balance valve crossover piping.
    As @plumbworker mentioned, not many 1017 valves have this function.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream