I have a small standard CH system - 1 rad downstairs, 2 rads upstairs, Boiler + programmer + room thermostat downstairs, Pump + Hot Water Cylinder upstairs in airing cupboard.
My problem is this: if I turn only the Heating on all 3 radiators get hot but if I turn the Heating AND Hot Water on the Water gets hot, the two upstairs Rads get hot but the downstairs Rad remains stone cold (even the supply pipe is cold).
I was informed by someone "in the know" that this would be caused by a faulty pump so I've just fitted a shiny, brand new Grandfos pump but it has not made any improvement - the downstairs Rad is still freezing cold when the hot water is on.
My next thought is that maybe there is a problem with the Mid-Position Valve but I would have thought that it would switch off all of the Rads if it was faulty not just one of them.
I don't really want to blindly throw any more replacements parts at the system until I understand what is going on so any tips would be greatly appreciated.
My problem is this: if I turn only the Heating on all 3 radiators get hot but if I turn the Heating AND Hot Water on the Water gets hot, the two upstairs Rads get hot but the downstairs Rad remains stone cold (even the supply pipe is cold).
I was informed by someone "in the know" that this would be caused by a faulty pump so I've just fitted a shiny, brand new Grandfos pump but it has not made any improvement - the downstairs Rad is still freezing cold when the hot water is on.
My next thought is that maybe there is a problem with the Mid-Position Valve but I would have thought that it would switch off all of the Rads if it was faulty not just one of them.
I don't really want to blindly throw any more replacements parts at the system until I understand what is going on so any tips would be greatly appreciated.