Heating Driving Me Crazy Always Something!

[Imreadytorun]

So I have replaced the mororised valve, as I had a problem when the system was just heating water, it would turn the radiators on. This solved the problem. Now the heating will not come on at all after it reaches 16, unless I move the thermostat on the hot water tank to 80 rather than 65. The system has drained down, all the radiators bled so it's not air in the system. I have even replaced the pump to make it more efficient getting the water round, and I just don't know where to go from here, any ideas appreciated!

 

[NozSpark]

TBH it sounds like your heating is wired through your hot water controls somehow,, for a start all the wiring could do with checking

 

[SPECIAL LOCATION]

The motorised valve you replaced...  Is it a three port valve working both heating and water..?

Or is it one of a pair of two port valves one for heat one for water?

If its a three port valve then as well as the "Water ON" and "Heating ON" signals you also need a "Water OFF" signal to get the valve to position itself correctly.....

If one of these is missing or they are swapped over incorrectly then it would give symptoms of the wrong thing heating up as the valve body will be in the wrong position!!

Who wired up the new valve..?

Did you verify the original valve was wired correctly..?

Do you have any wiring drawings of how your system is wired..? 

Need a bit more info to give any more accurate info..

:coffee

Just to add...  If it is a 3-port valve you need...

Heating ON from prog/timeclock - via room stat - to White of valve.

Water ON from prog/timeclock - via cylinder stat - direct to boiler+pump.

Water OFF from prog/timeclock AND from cylinder stat - to Grey of valve.

Orange of valve - to boiler+pump.

Wiring colours used between stats progs & valves could be anything depending on who wired it up!