honeywell ST699

3 Nov 2011
Reaction score
United Kingdom
HI . moved in to the house where honeywell ST699 is installed .Both switches water and c.heating are on constant position.Problem is that central heating is not working -red led is on., . Central heating start to work when hot water is heating in this same time . that mean that i can switch central heating off completely and it will be still on during heating hot water .I removed programmer and fit a link between L and CH ON, and L and HW OFF
No reaction.
may it be programmer ?
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what I discover today morning is , when hot water switch was on const. (heating work as well-but was off) I could not switch it off . Had to switch main fuse off and on again , and then it was off.So few second after I had switch hot water on again boiler start and could not switch it off again . Than like before main fuse -off , than on and boiler was off. Did check again now in the evening and it is possible to switch hot water off.
Bt still heating switch without reaction.
How to check mid valve?

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