Centrl Heating Pump Speed? I have a three bed house beside gas central heat & a...

I have a three bed house beside gas central heat & a hot water container. The pump in the airing cupboard have three speeds. On the fast speed, its impartially noisy & I can hear it humming when it starts up within the morning, I find this fairly annoying.

There are two slower speeds which are progressively quieter, but I don't fathom out the effect of the pump speed and heating the house.

Does anyone know the optimum pump speed for helpfulness vs quietness?

All info welcome !
Night storage heaters move about cold promptly?
Answers:    There is no optimum speed for a circulator.
Set the "pump" at a number that will fry all the radiators including the one farthest away from the boiler, try 1 for an hour, and if not successful ,try 2, and finally 3,
From experience Number 2 is collectively OK
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I have a three bedroom house and my pump is set on 2 and it runs 7 radiators hope this help.