Central Heating pump?

Since having a new Baxi boiler, pump and 3 TRV's fitted we've noticed a lot of swooshing noise that reverberates throughout the radiators and pipework, very annoying at nightime. There doesn't appear to be air in the system but I think the noise is caused by the pump. It is a "Circulating Pumps" (CP5m) with 3 settings. Increase the pump speed and the noise gets much louder but left on the lowest setting it is still excessive and seems to get worse as rad valves close. We were told to have an auto bypass valve fitted (which we did) but that hasn't made much difference. When the boiler is off the pump keeps going for 8 minutes (which I believe is normal) but during this time the swooshing noise gets worse but turn the pump off and the noise stops.

I was wondering if the pump could be too powerful for the system as even on the lowest setting the rads get hot? Or is there a better pump that would be better? Thanks.

Reply to
Mark
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I would try a Grundfos Alpha pump. These automatically reduce power as the resistance increases and flow decreases.

.andy

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Reply to
Andy Hall

Mark

Before you change the pump, was the system quiet before you had the new boiler, pump and 3 TRV's fitted?

If you employed someone to do this work then I think that it is their responsibility to get it working properly. Hopefully you haven't paid them yet!

Al

Reply to
Al

You may need to adjust the bypass valve if the installer left it set on too-high a pressure setting.. According to the instruction sheet for a Myson valve, it says -

  1. Ensure radiator valves are fully open.
  2. The bypass valve is initially set at the lowest pressure setting (With the Myson it is fully anti-clockwise to 0.2 bar)
  3. Slowly increase the bypass valve setting until the radiators heat normally.
  4. Check the radiators balancing (I think you need pipe thermometers to do that properly) and ensure the system is working normally.
  5. lock the bypass valve in the set position by use of the locking screw.

If all that does not work, then maybe you could invest in the Grundfoss Alpha pump as suggested by Andy Hall.

Dave

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