pumps?
- Thread starter chimpboy
- Start date
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Ok, I'm new to all this, but the Grundfoss data sheets define the first number as the nominal port diameter in mm, and the second number is the maximum head in dm (decametres). i.e. 50dm = 5m.
So, if I step up to 25mm ports, will I see a slightly lower flow speed through the pump and so less noise at full speed?
So, if I step up to 25mm ports, will I see a slightly lower flow speed through the pump and so less noise at full speed?
Nearly right! But it's decimetre (one tenth of a metre) so 50dm = 50 tenths or 5m. A decametre (dam) is ten metres so 50dam is 500 metres!
As far as I know it won't make any difference. Though I have often wondered why the standard CH pump has 15mm ports when the pipe size is 22mm. Presumably because on the outlet you are goinf from a small port into a larger pipe. It would be different if you had a 40mm pump connected to a 15mm pipe. That's my theory, if any one has a better explanation ....
In any case, the required flow speed is dictated by the output of the boiler.
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