Faulty diverter valve?

[Des Jennings]

I have a Worcester Bosch system boiler and I'm experiencing an issue where occasionally I can put on HW on its own but more often than not I have to have the CH on as well. Sometimes the HW works for a couple of weeks without the CH on, then suddenly, I can't call for any HW. What I have noticed is that when the CH and HW are on at the same time, the situation is remedied for a short time the next time I call for HW. Is this a sticky diverter valve or something electrical outside the valve itself?

Thanks.

 

[CountryFan]

Sounds like a 3 port valve fault.

 

[Des Jennings]

Sounds like a 3 port valve fault.

Thanks. It's actually a 2-port valve. HW came on without a problem this morning. There was no need for CH to be on, but I can guarantee that sometime in the next few days, it will not fire up. That's why I was wondering if the valve is actually receiving an electrical signal to fire up on the occasions that the HW fails.

 

[CountryFan]

Thanks. It's actually a 2-port valve. HW came on without a problem this morning. There was no need for CH to be on, but I can guarantee that sometime in the next few days, it will not fire up. That's why I was wondering if the valve is actually receiving an electrical signal to fire up on the occasions that the HW fails.

If that’s the case it need proper fault finding. Testing the voltages when it’s in a failed state.