Problems with 3 position valve

[dbharrison]

My Central Heating system is providing Central Heating and Hot Water but does not appear to be controlling propperly. When the Central Heating comes on first (Hot Water OFF at this point) the valve goes to the mid position thereby providing both Heating and Hot Water. This situation continues until the Hot Water comes ON and the water in the tank is up to temperature. At this point the valve goes to the Heating position. Becuase the valve is initially in the mid position the water in the tank often heats above the required temperature. If both Heating and Water are switched off the valve returns to the Hot Water position.
Th valve itself appears to be working correctly but is not being controlled propperly. Any suggestions would be gratefully received

 

[spraggo]

The valve appears to be working OK, check that the cylinder stat is set to 60c and is situated approx 1/3 up from the bottom of the cylinder.

spraggo.

 

[seco services]

When the Central Heating comes on first (Hot Water OFF at this point) the valve goes to the mid position thereby providing both Heating and Hot Water.

no the valve should go to heating only position. if only heating on hw off.
check the grey for 230v

At this point the valve goes to the Heating position.

grey becomes live from the cyl stat satisfied.

If both Heating and Water are switched off the valve returns to the Hot Water position.

only if hw was last to call.
if heating was last to call and valve still falls to hw only then again i would be checking for power on the grey.



heating only hw off check you have 230v on the grey from the programmer.