No Hot Water unless Central Heating on

[duckface]

Vaillant 242/1 E

If the central heating is turned on then hot water can be operated ok. If the control is turned to just Hot Water then when a hot water tap is turned on nothing happens. Is it the diaphragm or diverter?

thanks

 

[kevplumb]

View media item 8355
when you turn on a hot tap is the cam behind this bit moving

 

[duckface]

Simple answer, no

 

[kevplumb]

could be
sec heat ex scaled
diaphram in water section
sticking pin in water section
lack of cold flow into boiler

 

[duckface]

but if the HW comes on all ok when CHW is on then diaphragm or sticking pin seem good possibilities?

 

[OLLIE20]

Also check all the cappilary tubes they generally get blocked up and the servo doesnt make switch, god these boilers were over engineered, also not all parts available 4 these any longer is it not a VCW