M
M2RTY
Hi and thanks for looking at my (first) post 
We bought a house that had not been used for a couple of years, the boiler was not working and the wires had been disconnected, so we replaced a few parts on it, rewired it, and connected it all together to get it working again.
Details of the set up are as follows:
Baxi Solo Boiler
Cylinder thermostat on side of hot water tank
Honeywell electronic timer ST699 located next to boiler
Honeywell dial room thermostat located next to boiler
The heating works fine at the moment when set on the timer mode, I currently have it set to come on twice a day for an hour in the morning and an hour in the evening and the heating works fine.
However, if I turn the hot water on (either manually via the slider or automatically via the timer), it works and heats the tank in the loft, but after 30 minutes or so it starts to heat the radiators in the house too, even with the heating turned off on the controller (and the red light for heating not illuminated) – is this normal?
Also, once the hot water is turned on (either manually via the slider or automatically via the timer), even when I turn it off again, the boiler wont turn off, it just keeps running and heating the water, until I cut the main power to it and reset the timer – even sliding the slider to the off position won’t turn it off. The red light turns off on the timer unit, but the boiler keeps going. I have not left it more then 30 minutes or so, but guess it will just keep going? Unless it still goes for a set time for a reason after the being turned off – but I very much doubt it?
If I use the +1 hour buttons, the heating or hot water comes on fine, but after 1 hour it won’t turn off again. It just keep going until I turn the slider to off and then back to twice.
It's had a new diverter valve in the loft and the boiler has been serviced as it originally would not fire up at all (new ignition, vacuum hoses, fan etc) .
Originally I suspected it was a wiring issue we sort of guessed how it all went together when we bought the house. However, after reading a few posts, the timer control units seem to fail a lot and cause random events like I am experiencing, and could be faulty relays inside the timer unit. I have priced a new ST699 up, and think it would be a much better option to replace it altogether with the newer (and cheaper) ST9400C. I have found the replacement wiring guide for upgrading the old one to the new one, so I think I will do this first and see how I get on?
I will also buy new thermostat as this now looks to be not working correctly. It sometimes does not cut the boiler off when it “clicks” when I move it and it equals the temperature of the room. For what they cost I will stick a new one on anyway. Again could this be to a faulty timer unit?
If the new control unit still does not fully work, does anyone know any good heating engineers in Darlington who could take a look at the wires for me and rewire the couple that could be wrong?
Many thanks all
Martyn
We bought a house that had not been used for a couple of years, the boiler was not working and the wires had been disconnected, so we replaced a few parts on it, rewired it, and connected it all together to get it working again.
Details of the set up are as follows:
Baxi Solo Boiler
- Model: WM 50/4 PF
- Seriel Number: 008953
- GC 41-077-44
- Cat 1N
Cylinder thermostat on side of hot water tank
Honeywell electronic timer ST699 located next to boiler
Honeywell dial room thermostat located next to boiler
The heating works fine at the moment when set on the timer mode, I currently have it set to come on twice a day for an hour in the morning and an hour in the evening and the heating works fine.
However, if I turn the hot water on (either manually via the slider or automatically via the timer), it works and heats the tank in the loft, but after 30 minutes or so it starts to heat the radiators in the house too, even with the heating turned off on the controller (and the red light for heating not illuminated) – is this normal?
Also, once the hot water is turned on (either manually via the slider or automatically via the timer), even when I turn it off again, the boiler wont turn off, it just keeps running and heating the water, until I cut the main power to it and reset the timer – even sliding the slider to the off position won’t turn it off. The red light turns off on the timer unit, but the boiler keeps going. I have not left it more then 30 minutes or so, but guess it will just keep going? Unless it still goes for a set time for a reason after the being turned off – but I very much doubt it?
If I use the +1 hour buttons, the heating or hot water comes on fine, but after 1 hour it won’t turn off again. It just keep going until I turn the slider to off and then back to twice.
It's had a new diverter valve in the loft and the boiler has been serviced as it originally would not fire up at all (new ignition, vacuum hoses, fan etc) .
Originally I suspected it was a wiring issue we sort of guessed how it all went together when we bought the house. However, after reading a few posts, the timer control units seem to fail a lot and cause random events like I am experiencing, and could be faulty relays inside the timer unit. I have priced a new ST699 up, and think it would be a much better option to replace it altogether with the newer (and cheaper) ST9400C. I have found the replacement wiring guide for upgrading the old one to the new one, so I think I will do this first and see how I get on?
I will also buy new thermostat as this now looks to be not working correctly. It sometimes does not cut the boiler off when it “clicks” when I move it and it equals the temperature of the room. For what they cost I will stick a new one on anyway. Again could this be to a faulty timer unit?
If the new control unit still does not fully work, does anyone know any good heating engineers in Darlington who could take a look at the wires for me and rewire the couple that could be wrong?
Many thanks all
Martyn
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