Honeywell ST699

Product Information

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. 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!

So the wire to terminal 8 from the boiler is throwing me as all the conversion examples from the norm basic set up on the st699 to the st9400c do not mention this direct connection from the boiler only a loop from 8 to 5 pins that can be removed.

Ive had this heating programmer for 20 years and it works fine unless I have a power cut, which happens out in the sticks occasionally. One installer may use a blue wire for a certain purpose another may use a brown for the same function.

It's often the case that a standard cable L, N, E is used to connect a room thermostat and the N conductor is often used as the switched live. Is it a DIY job or something a professional should do, baring in mind I don't want to replace the whole system, just the timer/thermostat of the existing system? However, the ST699 has two simple switches inside, one for heating and one for hot water, and so does the Hive. I would really like to get rid of the thermostat in the hall altogether for cosmetic purposes and I would love to have more flexible control over the heating than the draconian timer we have now that has one setting for all days for both the heating and the hot water at the same time.

If the cores were truly unused then they should be safely terminated in separate connections on a terminal block. If the motorisied valve seems to behave as it should but the boiler doesn't turn off afterwards, I'd suspect a sticking microswitch inside the motorised valve.