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Indirect water heater placement long run piping vs recirculation line.

heathead Member Posts: 234
So adding indirect water heater to house that had two water heaters two different sides of house. House is piped in 1/2 copper. I know it's small. 3.5 baths. House is 80 feet long. One side kitchen and bath that are used during day, and bedrooms other half. My thought was put indirect on kitchen half of house most water used all during day and bedrooms would be once in morning and once at night. Not waiting long near kitchen sink for hot water and one heater already their near inlet for water service. So if I do that I need to run the pipes from the boiler 80 feet, total round trip 162 feet to IDWH. 1 1/4 copper 6 GPM is max flow through boiler heat exchanger with 3.3 feet of head available on internal pump left for indirect water heater and piping. Tank coil is .7 pressure drop at 6 gpm and .004 per foot of 1 1/4 type m copper. .004 x 162 is .648 ft of head for pipe. Is the math right. My hesitation is cost for copper pipe. VS designing recircultion loop and pump complexity. How many double 1 inch pex al line would I have to run to have it make the equlivent of the copper 1 1/4 head flow. I know just suck it up and pipe it once and be done? Or just deal with wasting water at kitchen sink with 40 feet of 1/2 copper before hot water arrives. Thoughts


  • mattmia2
    mattmia2 Member Posts: 9,843
    The pipe to put the indirect at the fixtures will cost much less than the nonferrous circulator and controls for a recirculation loop. Could also pipe it in pex. just insulate whatever you use well.

    Is the kitchen/bath a full bath or just a half bath? Where is the laundry? I might think about an indirect at each location, a small one if the kitchen isn't supporting a full bath or a conventional washer at the kitchen/bath.
  • Jon_blaney
    Jon_blaney Member Posts: 321
    I had a recurc installed when I added a master suite addition build on my house. Not worth the cost to install or use. I had a constant circulation system. It is expensive to run so I turned it off. Just put up with waiting for the hot water.

    Prime the system in the AM for the bathrooms by a quick draw at the bathtub. Quicker than you might think. Rinse your dishes in the cool water in the kitchen sink while waiting for the hot to arrive.

    I only pay for the water, no sewer charge.

  • hot_rod
    hot_rod Member Posts: 22,382
    Put a small electric tank at the far end? Fed from the distant indirect. A 6 gallon 120V  maybe
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream