Honeywell ST699

Product Information

I do know that there is a Grundfos pump in the airing cupboard next to the cylinder and two white boxes connected to the pipes which I believe are motorised valves, but that is the extent of my knowledge - the airing cupboard is a bit of a spaghetti junction or pipes and wheel valves, and I don't really know what any of them do! Whilst wire colours do necessarily mean anything on a central heating system, the combinations you have are a bit unusual.

In your photo the wires would appear to be in the correct terminals as far as I can tell from a photo, when you can't see what is on the other end of them all. For example, one answer shown below mentions the link from 5 to 8 being removed which I dont have, I have a direct link to 8 from the boiler, so not sure where to wire this to on the st9400c. Page 3 of the pdf wiring diagram upload attached shows the basic system 2 with room thermostat wiring layout I currently have exactly. At then end of the day, from an electrical point of the ST699 has two on/off switches in it; one for heating and one for hot water. You have everything necessary to do what you want, but the wiring in the junction box on the wall needs to be checked, as will the junction box on the floor.There is also an equally old looking thermostat dial in the hall (just above the radiator which doesn't strike me as an ideal location! Here’s the embarrassing bit: I then realised that the indicator light for ‘once’ was coming on ‘as programmed’ because ‘once’ was pretty much all day on the programme.

The darker blue wire looks like an actual neutral wire , could the light blue wire be a switching wire that should have gone somewhere else? Is it as simple as looking at a wiring diagram for the ST699 and attaching to the corresponding connection of a new timer? On the plus side in the hall staircase and landing is not connected to the open plan space and the front door is a traditional wood design with thick curtain to reduce the draught in winter, so although the thermostat is directly above the radiator (small double) at light switch level it is still a cold space as it is next to the front door and the radiator has to heat up the stairs and landing too so it sort of still works. When you have it, post details of it on here and someone will be able to advise you how to install it. Some of our partners may process your data as a part of their legitimate business interest without asking for consent.The Honeywell ST699B-1022 Electronic programmer is part of the Honeywell controls range at PlumbArena. In this instance, the heating controller operates the motorised valve and inside the motorised valve is a small switch that turns the boiler 'on' when the valve is open, so it's the motorised valve that's actually starting and stopping the boiler, and it's not unknown for these switches to play up and become intermittent.