Puzzling Glow-worm 18HXi boiler fault

[pennine_lad]

Hi

Boiler has been off for a couple of weeks and switching back on. No fault codes but behaviour odd. Has had an annual check / service.

HW comes on quickly gets up to temp set 63 degC then shuts off. In 5 mins watching it, it does not come back on.

When CH just on it does not come on at all.

When both HW and CH on it does stay on.

Do these fault suggest electronic / settings at boiler or something downstream like pump or pipe blockage?

Thanks for any leads.

David

 

[Stuckinarut]

Possible 3 port mid position valve failure

 

[pennine_lad]

Thanks for the lead. It is a Tower MP322C/H with a visual slot on top to show motor paddle position.
A side is HT (CH), B is HW, middle both.
Tried selecting HW and CH only on boiler and paddle stays in the middle.
There's a manual lever click stop to manually set and that is not moving the valve setting.
So definitely worth following up. Box is labelled motor can be changed without draining.

 

[Stuckinarut]

Yep, definitely sounds gubbed. Not sure how reliable tower are, I know they're cheap though