3 way valve and pump

[ballyclover]

new developments

new pump installed and upstairs radiators got hot along with HW.

Downstairs got warm but v slow.

i have set the hw to 0 to force CH on and now all and lovely and hot.

so when i turn water back up it will no doubt cut CH to downstairs.

Does this tell anyone anything.

was thinking about the timer and the wiring, thing is, it was working fine till a few weeks back, changed the pump and now we are getting somewhere

 

[ballyclover]

hi guys,

been a while, i replaced the pump and everything seemed to work fine, not much heat downstairs but upstairs worked well.

well things are back to how they were now, the pump i am sure is fine.

If i turn the thermostat on the hot water tank to 0, thus forcing the heating of the radiators it works fine, as soon as i turn the thermostat back up the radiators stop working.

I have felt the two pipes coming from the 3 way valve and the one which goes to the radiators is always cold unless i do the above.

Anyone got any ideas?

thanks

 

[MANDATE]

The fact your system does not have the correct capability means it can never work as it should.
Your choices seem to be either HW only or HW shared with CH.
When selecting HW shared with CH, the valve is supposed to move according to demand. So it could be in any of the three positions (but not in your case).
I believe you are only getting your radiators hot at a reduced rate while there is also a demand for HW. When HW is satisfied, the cylinder stat cuts the boiler of as it should and then you get nothing until HW is in demand again. Everything suggests you have inadequate wiring for the valve to function as it should. programmer? cylinder stat? power to 'grey' wire?