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Do I need this circulation pump?

  1. Jul 24, 2008 #1
    The schematic shows a central heating system. I'm wondering if I can drop the twin pump? If each of the single pumps are powerfull enough to bring the water around through the heat exchanger then why do I need the twin pump?

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  2. jcsd
  3. Jul 24, 2008 #2


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    Science Advisor

    It would depend on what flow rate you want. Two equally rated pumps in parallel will put out twice the volumetric flow rate of one. Perhaps the designer had economic reasons in mind (i.e. maybe it is less expensive to have two smaller pumps than one large pump).

  4. Jul 24, 2008 #3


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    Staff: Mentor

    It's a primary-secondary pumping system. The double-pump keeps water flowing around that loop regardless of what the other loops are doing. That's important because some boilers don't like low flow rates.

    It's a simple enough system, though, that I might be inclined to break the primary loop (just add a valve where it loops around), flip the valves around, and get rid of the secondary pumps! The 3-way valves will ensure you always get the same flow rate through the boiler regardless of if the flow is going out to your heating system. If the system is to be expanded later and/or if the boiler flow rate is higher than the heating system flow rate, you can use the valve added to the boiler loop to regulate that via balancing it for a certain bypass volume.
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