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The Hidden Costs of Hidden Pumps

HeatingHelp Administrator Posts: 600
edited August 2018 in THE MAIN WALL

The Hidden Costs of Hidden Pumps

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  • RWhite14
    RWhite14 Member Posts: 1
    The biggest obstacle is up front cost, usually energy efficient equipment cost more to purchase, if legislation is not passed to phase out the less efficient equipment it will still be used whilst it is cheaper to purchase.
  • Gsmith
    Gsmith Member Posts: 429
    Remember too that the cost of electricity is much higher, maybe 2 to 3 times higher than in the US, which makes a bigger incentive for saving energy . I noticed recently for me, in northern NJ that my summertime electric bill including AC is half my cable tv / Internet bill, and I don’t think I’m atypical. Until power prices rise compelling consumer interest may not be easy to achieve.
  • @RWhite14 unfortunate but usually true
  • scott w.
    scott w. Member Posts: 200
    As a home owner how do you know when you have pumps that consume high amounts of electricity?
    How does one do the math to determine when it makes economic sense to call the plumber or boiler guy to change out 5 or 6 pumps to something more efficient?
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,433
    @scottW take photos of them and post them here for opinions.
    Retired and loving it.
  • jumper
    jumper Member Posts: 2,139
    Old saw is that more efficient heat transfer requires more pumping energy. Would some positive displacement pump require less power than normal centrifugal?

    Also we see more and more VFD s. Can those compensate for incorrect pump selection?
  • Jamie Hall
    Jamie Hall Member Posts: 22,162
    A positive displacement pump might be more efficient (use less power) if it is properly sized or if it is variable displacement (much money. devoted maintenance). More important, however -- and applies to both questions, is to size the pump so the system flow curve matches as closely as possible the maximum efficiency point (or curve, in the case of a VFD) of the pump.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 20,809
    scott w. said:

    As a home owner how do you know when you have pumps that consume high amounts of electricity?
    How does one do the math to determine when it makes economic sense to call the plumber or boiler guy to change out 5 or 6 pumps to something more efficient?

    The label on the circulators generally have the data, usually indicated in watts.

    But it is also about how much work they do with the amount of electricity they consume aka wire-water efficiency.

    A standard type wet rotor circulator common in residential use is in the low 20% efficiency, when running in the best operating condition.

    New ECM style circulators will do the same work with 50% or more electrical savings.

    So add up the power consumption, estimate how many hours a year they run X electricity cost to get your answer. In a common heating climate maybe 3, 4- 5000 hours per year?
    Degree day weather data, available online would be another way to estimate pump run time.

    KillOWatt meters are an inexpensive way to get actual consumption.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,205
    Its funny, I've been harping on this topic for years ( and usually ignored). The huge increases in the use of electricity for "high efficiency" hot water boilers makes them even less attractive once you add in all the true energy usage of the boiler. That's one of the reasons why I recommend cast iron still...the actual overall energy usage is often not that much different especially considering the "grid efficiency" ( about 70%) of direct burning of natural gas is more than twice the "grid efficiency" ( about 33 %) of electricity. Add in the increased energy usage for manufacturing due to the much shorter service life of "high efficiency" boilers and the increased energy usage to maintain them ( more repairs parts and service calls), and I wonder if there is any real improvement at all. Of course that's also why I prefer steam, its even more efficient yet since there is almost no electricity usage at all for small atmospheric boilers and very low overall usage for power burners units. For comparison in a 6000 DD65 climate( not sure the efficiency of HVAC transformers) for typical winter loads ( 60% capacity):

    Small residential atmospheric steam boiler: 0.01watts /sq ft
    Large multi-unit atmospheric steam boiler: 0.0017 watts/ sq ft

    Large multi unit power burner ( 84 to 87 % thermal efficiency) steam boiler: 0.02 watts per sq ft

    Small res atmospheric hot water: 0.039
    Large multi-unit atmospheric: .045 watts/ sq ft

    Large high efficiency boiler .05 watts/ sq ft ( figuring 2 pumps and an ECM fan plus some control power)

    Still about 1/10 of forced air but the operation of pumps in the system has been ignored way too long.

    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • EYoder
    EYoder Member Posts: 60
    edited August 2018
    With a hot water system designing around a larger delta T would really help in reducing electricity consumption. I understand some systems it's easier than others but it should be a goal. I think. :)