Hot water thermostat turns off heating - Help

[John T]

Hi
Ive just changed the Honeywell (V4073A) motorised valve in my central heating (Y system). It has a new Honeywell programmer (ST69)as well and if both heating and hot water are on together the heating goes off when the hot water thermostat turns off. If i isolate the hot water system on the programmer the heating works fine . As soon as i have it working together the hot water thermostat keeps over riding the heating. I am sure the wiring is correct.

All help appreciated.

regards

John T

 

[oldtimer]

Not sure but the HW might have priority over the CH so once the HW tank is up to temp the CH is allowed to work

 

[snowhead]

Have you changed the whole valve?
Are the pipes correctly connected A, B, AB?

Was it a Honey well before thew change?

Did you change the programmer at the same time as the valve?

 

[guest119]

Sounds something like the tank stat n/o and n/c the wrong way round.

 

[John T]

Have you changed the whole valve?
Are the pipes correctly connected A, B, AB?

Was it a Honey well before thew change?

Did you change the programmer at the same time as the valve?

Hi
Yes it was a Honeywell valve and i have just changed the programmer thinking that was the fault. But afraid the new programmer makes no difference