Honeywell ST699

Product Information

Whilst wire colours do necessarily mean anything on a central heating system, the combinations you have are a bit unusual. For example blue being used for CH on & HW on and brown for hot water off. That's based on your indication above about wiring on ST699. The only reason I wasn't going to bother with downstairs was because we don't really have trouble with the heat levels downstairs, if anything it's hard to keep it warm even when heaters are on constantly as it is a large open plan space and has a very large bay window at one end and French doors at the other. If so, you have a fully pumped system, but it's not being used to its full ability because the ST699 has not been wired correctly. Fortunately the changes I mentioned (motorized valves!) will not be necessary. It's just a case of installing a new programmer, correctly wired, and a thermostat. Yes N & L were previously in N & L on the ST699. Regarding the locations of the other cables, I'm pretty certain that I did the following swap, although, I'm second guessing myself now:

Find a Plumber Plumbers Looking for Work - Post Here Looking for a Plumber? Post Jobs Here Looking for a Heating Engineer? Post Jobs Here Find a Renewable Energy Specialist Plumbers Directory Listings Whilst Hive has an earth terminal it isn't actually connected to anything. Hive doesn't need an earth connection itself. The terminal is just there to 'park' any earth wires that happen to be present and keep them together so that they are safely out of the way of the other terminals. As you say, the junction box on the floor is just to extend the cable from CH valve, so it doesn't hang in the air.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! I just opened them all when I first moved in and hoped for the best, I've never touched them since lol. Can you please provide a picture of the ST9400 wiring. Do you also have any pictures of the prior ST699 wiring to compare. If you don't have a picture of the ST699 wiring can you carefully outline the connections on the ST699 (terminal, wire colour, etc) and to which terminals they were moved for the ST9400. You said "I have cables linking:" did you mean "I HAD cables linking.. on the ST699". As you have power & lights on the ST9400C i guess that "Blue-A" and "Brown-B" were previously in ST699 N & L respectively. But can you say of the other four which terminals on the ST699 did they originate.

The one on the floor is more straight forward - it's just a like for like pass-through to extend the cable... This is the existing wiring of the st699 I want to upgrade to a hive. I follow everything except the second blue wire that is going into the neutral port. 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? Hot water and heating calls currently work fine , occasionally the boiler fails to turn off but this is intermittent.Thanks for bringing this to our attention, this has been a recent change to our system. We agree with you that it is not quite right and we have now edited our system so as not to be so confusing. Ideally I would like a modern digital timer with flexibility for multiple programmes for different days and times and a wireless thermostat in the living room to control the temperature. And one that doesn't lose all it's settings whenever there is a power interruption! Yep like that - they're called 'Lifestyle 2-port motorised valve', there is one underneath the pump on a pipe that doesn't go into the cylinder, and one on a pipe that come off the other pipe and goes into the cylinder about halfway up it. As an aside my 'bay' window is more like a box on the side of the house, it's not full height and as far as I can see the large window sill is the only thing separating it from the outside, which seems like a horrible design from an energy saving/warmth point of view considering all the other walls have cavity wall insulation. Using "ST9400c Wiring 1.jpg" going left to right can you indicate which core went into which connection on the ST699

I've been doing a lot of research on heating systems recently, and for those that have seen my other topic I've been having trouble with a cold radiator which I think will need new valves. I'd recommend you tidy the wires a bit. The number of loose strands is a disaster waiting to happen. PF Community Forums General Off-Topic Chat For Sale & Wanted Make a suggestion about the forum in generalI opened up the Honeywell wiring hub near the boiler power switch to try to get a better idea of what the wires were doing Just think what if your away for a while in the winter and it was like last year and the power goes off. For 5mins work and 5 quid could save you loads of hassle. But this has got me thinking, why stop there? Our boiler is controlled by an ancient looking Honeywell timer which from Googling I think is a Honeywell ST699 (except our version features a delightful brown/beige colour scheme!) 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!).