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Which Hot water recirculating pump

leaking
leaking Member Posts: 59
in THE MAIN WALL
I have the smallest B&G recirculating pump on a 100ft hot water line and it doesn't help at the end apartment. I believe I need a bigger pump, or maybe it just isn't pumping- but it's running. What are the most efficient pumps sold? Are they Brushless motors? How do I size a pump? I just saw an and for a variable speed pump, is that the way to go?

Comments

  • hot_rod
    hot_rod Member Posts: 23,000
    The smallest pump you can buy should do that. B&G sells the small ECM Laings

    Grundfos, Taco, Armstrong, Wilo, etc all offer high efficiency recirc pumps

    Officially you measure the Piping, fittings, and insulation if any to come up with the exact load. Most pumps are multiple or variable speed to dial in

    Look for a 3-5 degree drop from tank to return
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JUGHNE
    JUGHNE Member Posts: 11,244
    With the existing set up, what is the return water temp??
    If you have that 3-5 temp drop as Hot Rod said, then you have piping issues that I don't believe a larger pump will help.

    The recir line may not go completely to that last apartment.
  • leaking
    leaking Member Posts: 59
    100 ft from the pump the return doesn't even feel warm, it takes maybe 2 minutes to get warm water out of the faucet,
  • Zman
    Zman Member Posts: 7,610
    Are the pipes insulated? Are they run in a heated space?
    I have never seen a residential DHW recirc where the pump is too small. I suspect a piping issue.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • JUGHNE
    JUGHNE Member Posts: 11,244
    Pump may not be running. Tip of screwdriver against pump body with handle in your ear, switch on and off, you should hear the difference.
  • leaking
    leaking Member Posts: 59
    It's an apartment building , on a Corner lot , the building is 12 units 2 story but I have only 4 end units being recirculated, the system has a dedicated return, pipes all insulated with foam, heated basement, pump is running. Yes a plumbing mistake is possible but I did get the smallest pump.
  • leaking
    leaking Member Posts: 59
    Can a pump run and be broken and not pump?
  • heathead
    heathead Member Posts: 237
    Is their a check valve on the return line that may be stuck?
  • Dave H_2
    Dave H_2 Member Posts: 576
    I guess the next question is has it ever worked?

    And how is it controlled, is it just on 24/7 or some sort of temp control?
    Circs can have power going to them and not be circulating. Is it all bronze or stainless....?
    What size pipe are you feeding and what type of water heater?
    Tankless style water heaters need bigger circs in order to get the unit to fire. Tank style can use smaller circs.

    Dave H.

    Dave Holdorf

    Technical Training Manager - East

    Taco Comfort Solutions

  • leaking
    leaking Member Posts: 59
    Yes check valves, yes it could be stuck, water heater is 17 yr old AO Cyclone, I think 85 gal 199,000 btu or about, I think an old bigger pump was better , it works a bit. This is a small pump, B&G nrf-22, it only consumes 92 watts.
  • leaking
    leaking Member Posts: 59
    It's on 24/7, bronze I believe, piping looks large out of the AO 85 gallon Cyclone, but the return I think is 1/2".
  • Dave H_2
    Dave H_2 Member Posts: 576
    You say a bigger one was there, So when was the nrf22 installed?

    that circ should be more than enough circ to get the flow you need.

    Dave Holdorf

    Technical Training Manager - East

    Taco Comfort Solutions

  • leaking
    leaking Member Posts: 59
    I put in the B&G nrf22 probably when the AO cyclone went in, maybe 17 - 18 years ago. Could a check valve be bad ? How would I know if it's bad
  • JUGHNE
    JUGHNE Member Posts: 11,244
    Short of opening the check valve up, about all you could is to wrack it with a rubber hammer or large screwdriver handle. If stuck shut with the pump on it may jar it loose, it that is the problem.
  • leaking
    leaking Member Posts: 59
    I checked the pump temp yesterday and today at the pump and at the far delivery area after turning it off all night. With an IR thermometer. The bypass near the pump seems ok , since one side is much hotter. The temp at the faucet far away is at least 10f lower when the pump is off vs when the pump is on, but it still takes 3 minutes to reach temp, when pump is off, it can't reach temp, it's -10 lower. That is why I thought a bigger pump was needed.
  • JUGHNE
    JUGHNE Member Posts: 11,244
    Some recir systems that have a TEE branch near the end that might have checks for the branches where they split. Maybe even balancing valves.

    I found one with the check valve installed backwards, but that can not be your problem if the system used to work.
  • PAXRod
    PAXRod Member Posts: 6
    I had a similiar issue with a circulation hot water pump (TACO) which works off a timer- I stopped getting hot water when I should have. Pump hummed like it was running so I assumed a stuck check valve. Fortunately before replacing check valve I pulled the pump apart and the impeller was stuck - pulling it loosen it and it rotated easily. I had a different cartridge so I put that in and system works.
  • leaking
    leaking Member Posts: 59
    Ok thanks everyone , but I'm still not sure , :o:o
  • Hilly
    Hilly Member Posts: 428
    Only time I had a problem on a res circ was that it was airlocked. After the first I always just purge through the pump to be certain. The small ecm grundfos have been my main ones and I always had to purge them if there the water was drained in the building. After the first time it happened (I crapped myself because I thought I undersized the circ or my lines) I always check to make sure the circs are pumping the warm water when I work on those systems.

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