Problem with system: boiler only fires up in hw mode

[gasfun]

Hi,
Went to a customer today. System with heat only boiler. the boiler fires up in hot water demand , but not in ch mode.if hot water and central heating are called for everything works fine. My thoughts are diverter valve. But then boiler would fire up when ch is called for?

 

[Dotty]

Moving to private forum.

 

[Whn1]

So has a 3 port valve?

 

[AWheating]

y plan?

 

[R1CKY]

y plan?

Because it saves time in the long run.......

Probably the synchron motor in the 3 port valve has failed. When you select hot water, the boiler will fire without any input from the 3 port. The 3 port only does something when heating is selected.

 

[AWheating]

Because it saves time in the long run.......

what a bad joke!

why did i not think of it

 

[gasfun]

Thanks guys. Y Plan system. Going back tomorrow. Planning rocks yeh

 

[arran197]

You're mid position actuator is goosed. You could change just the syncron motor, but I usually change the complete head.

 

[gasfun]

Yes thanks. I just changed it and works fine. I just didn't know that the 3 way valve signals the boiler to fire up in central heating mode. Need to do the honeywell course asap. Thanks again for the help gentlemen