Central Heating Pump

Discussion in 'Plumbers' Talk' started by nodrog38, Apr 2, 2019.

  1. nodrog38

    nodrog38 New Member

    Thanks Sam, your help is appreciated
     
  2. nodrog38

    nodrog38 New Member

    Hi Sam, any progress with the above ?
     
  3. sam spade

    sam spade Active Member

    Sorry for not coming back - I completely forgot about your problem over the Easter weekend.

    1. From the 38 HXi pressure loss graph (attached) we know that, at full output, the flow is 1.633m³/hr and the pressure loss is 4.05m.
    2. From the UPS 25-80 graph (attached)we know that, on speed 3, a flow of 1.63m³/hr produces a head of 6.75m.
    3. This means that the radiator circuit is producing a loss of 6.75 - 4.05 - 2.7m
    4. We have already ascertained that the heat loss is only 28kW so the required flow is only 1.21m³/hr
    5. This means that the radiator loss reduces to 1.48m (loss is proportional to flow squared)
    6. The head loss of a CDi heat exchanger (attached)at 1.21m³/hr is approximately 1.6m. (Green line)
    7. The total head loss is therefore 1.48 + 1.6 = 3.08m
    8. The Alpha1 15-50/60 will provide a flow of 1.41m³/hr with a head of 4.22m (Alpha1 graph attached)
    9. A flow of 1.41m³/hr will produce a temperature differential of about 17C.
    10. The Alpha1 15-50/60 consumes about 35W

    38hxi pressure loss.JPG CDi Pressure Loss.JPG UPS 25-80.JPG Alpha1.JPG
     
  4. sam spade

    sam spade Active Member

    I forgot to add that if the UPS 25-80 is retained it could be set to speed 2 giving a flow rate of 1.63m³/hr and a head of 5.58m. The power consumption would be about 120W. The flow rate is equivalent to a temperature differential of about 15C.
     
  5. nodrog38

    nodrog38 New Member

    Thanks Sam you are a great help. Will probably change the pump out and have all new.
     

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