Central heating pump CP50

10 Sep 2006
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United Kingdom
Hi. I have a central heating pump CP50. On the speed setting is C1, C2, C3 to the right and minimum, medium, maximum to the left of the dial on the pump.

Could some kind person explain the difference between each setting on each side, as I presume C1 would = minimum, C2 medium, C3 maximum too?

Why is there 2 sets of speeds? Any preference to have? 5 radiator setup on 15kw boiler.

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C1, C2 & C3 are the traditional fixed speeds or (now called) constant curve, CC, if your pump is a 6M pump then C1 might be a 2M head, C2, 4M & C3, 6M, C2 at 4M should be adequate for 5 rads.
The min/max mode, left, is proportional pressure or PP control and is probably settable incrementally in 0.1M steps between say 0.5M and 6M, if you require say a 4M head for your system with all rads at full output, then you might set this ~ 5/5.5M to give you the required 4M head, if you have zoning or rad TRVs then as zone valves close or TRVs are throttling down then the pump head will reduce automatically which results in power saving and reduces the (sometimes) noise level in the TRVs. You could set this to its mid point or slightly higher and should work quite well.
John also helped me as I also have similar pump (newly installed).
see attached for application of CC or PP and other modes, basically its what stated above but in a tabular format for future reference.


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