3 way valve, whining radiators and flushing.

[giraffe]

I have had whining radiators for several months.

I have a two pipe open-vented with a boiler in the airing cupboard.
I also have a three-way diverter, a grundfoss pump and an air seperator.

Because of the whining and the nice weather I have decided to put a cleanser into the header tank after draining the radiators.

I am not sure how the 3-way diverter works and I switched it to manual to see what happened.

I refilled the system and put it on. The radiators at the top of the house got hot quickly and the ones downstairs took a long time to warm up.

One in the hall didnt warm up at all.

I then switched the 3-way diverter to auto and heard a lot of circulation happening downstairs and the radiator in the hall warmed up quickly.

It started to whine a bit until I adjusted the thermostat knob on the radiator.

Can anyone explain what is going on?
Should the 3-way be left on auto?

 

[wonderb0y]

yes it should be left on auto.

the whineing rad could be the pin sticking on the trv you could try re-greasing it, or if need be replace it.