How can I get hot water from my vaillant boiler - I have readiators hot bu ?

Diverter valve motor faulty ,you might have to change whole thing ,try on eBay with make and model number ,you might get half price

ltd
March 2012

Probably the HW flow sensor, Try turning on 2 or more taps, sometimes works, and will also rule out the switch itself. Different boiler, use different sensing, some are via a diaphram, which operates a pin, which pushes on a microswitch. If that type, once the front cover is off, you would be able to see the movement, or not. (probably with a plastic sheild over it, But you would be able to twist it to see the pin movement, (on the end of the 3 way valve) Some use more electronic means, test meter needed. If 2 or more worked, possibly diaphram in the 3 way valve, depends how you feel about it, can get them cheap from ebay.

SD
March 2012