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any suggestions on pumps?

icecreamfitter023
icecreamfitter023 Member Posts: 1
edited August 19 in Radiant Heating

hey guys. need some real world advice. just a refrigeration guy trying to build his own home.

want some confirmation on pump choice and whether or not these numbers work.

for reference I have to 2 zones. 1/2" pex. zone 1 is 3 loops at 300'. zone 2 is 6 loops at 250'. figuring for 30% glycol. primary / secondary piping

for a 20 delta t i came up with

zone 1- .633 gpm per loop. 2 gpm total. 7' of head.

zone 2- .53 gpm per loop. 3.5gpm total. 4' of head.

the alpha1 26-99 is the only pump that comes up in suggestions on Grundfos for both of these zones.

i was looking at the alpha 15-58 or the upse 15-58 but i fall well below the pump curve.

for a 10 delta T I came up with

zone 1- 1.266 gpm per loop. 4 gpm total. 21' of head suggested alpha2 26-99

zone 2- 1.5 gpm per loop. 6 gpm total. 13' of head. suggested alpha 15-58

any advice on if my numbers seems way off base. if 10 degree delta t is a pipe dream with the lay out i have ( is it even possible to get 1.5gpm through 1/2in pex?). is the 20 degree delta t where i will need to be and if so any suggested pumps to acheive these numbers?

thanks everybody.

Comments

  • GGross
    GGross Member Posts: 1,589
    edited August 19

    well you don't add the 2 head loss together assuming they are piped normally, if they are piped in series so one has to flow through the other first then your "furthest" zone via piping would just have a higher pressure drop (head)

    So your first example with a 20 degree delta T you would size your pump for

    (2 + 3.5) GPM @ 7' head (highest pressure drop)

    5.5 GPM @ 7' Head

    add a little fudge factor to that

    6GPM @ 10' head = Alpha 15-58 even if you were to add the head this would fall within the curve so not sure where the issue is there

    https://product-selection.grundfos.com/us/products/alpha-north-america/alpha-15-58-north-america/alpha-15-58-f-92603115?pumpsystemid=2743051322&tab=variant-curves

    or for example 2 with a little fudge factor

    10 GPM @ 25' head = Alpha 26-99

    https://product-selection.grundfos.com/us/products/alpha-north-america/alpha2-26-99-north-america/alpha2-26-99-f-99490916?frequency=60&pumpsystemid=2743051814&tab=variant-curves

    I would go with the 15-58 personally, especially if you are pumping each zone. If the 10 degree delta is very important then you would need a 26-99. feels a bit like overkill though.

    GroundUp
  • GroundUp
    GroundUp Member Posts: 2,392

    The 26-99 would easily support 3x what you have and is grossly oversized (though would modulate). Even the 15-58 will do nearly double what you have without issue. The Alpha 15-58 and two 3/4" Sentry zone valves would do a heck of a job here but if cost is of any concern, one UPS15-58 on each zone would be a great fit as well.

    I typically run my loops 250ft in residential homes and use 32% glycol, and a single 15-58 starts to max out at about 14-15 loops. I do typically use the Alpha 26-99 with zone valves and/or actuators when it's 3 or more zones and 15+ loops, but something like yours would be two UPS 15-58 (if a budget build) or an Alpha 15-58 with two zone valves.

    GGross

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