Honeywell ST699 Programmer Problem

[Mdljk]

I have a System boiler with a programmable room stat and a still very common Honeywell ST699 basic programmer - ten years old. I know that this crosses over into an ‘electrical’ issue but would appreciate if anyone could tell me if anyone has seen this fault and if it shows shows it is faulty and needs replacement obviously bu an electrician. Yesterday it no longer allowed either the CH or DHW to come on ‘twice’. It is fine in every other mode ‘constant’ ‘off’ ‘once’ but no longer allows ‘twice’ daily. Astonished to learn that this basic unit costs £100+ but will replace if needs be. Before I call out an electrician, from experience can anyone familiar with the ST 699 tell me if they have seen this fault before and if so does it indicates replacement. I have pressed the reset button but no change. Thank you

 

[Burger]

I haven’t worked on them so wouldn’t know. Maybe contact Honeywell technical?

 

[Mdljk]

Thanks. Good tip. Didn’t think I’d get through on phone but fast reply. Honeywell said that it is strange and unknown to them. Suspect slider is not making contact with. Advised a ‘hard reset’ = switch off for 30 min - then if no good dismantle and clean. I’ll let you know.

 

[Harvest Fields]

How did you get on mate?

 

[Mdljk]

How did you get on mate?

Hi Harvest Fields and thanks for the follow-up. Embarrassed to say that I stripped it right down and cleaned everything. Then bought a direct replacement from Screwfix. Same behaviour. 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 was expecting the ‘twice’ indicator to illuminate whenever I selected ‘twice’ - of course the light only illuminates during the two periods programmed. When I re-programmed to simulate this- bingo! it illuminated. So a simple misinterpretation of the functions. Prob was I filled in large holes caused by the boiler installation the day before and convinced myself that I had inadvertently fouled a signal wire to the boiler. Anyway back on wall. Returned replacement for full refund. Nil cost only lots of time wasted but thanks to all who responded and your good self.

 

[Harvest Fields]

Hi Harvest Fields and thanks for the follow-up. Embarrassed to say that I stripped it right down and cleaned everything. Then bought a direct replacement from Screwfix. Same behaviour. 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 was expecting the ‘twice’ indicator to illuminate whenever I selected ‘twice’ - of course the light only illuminates during the two periods programmed. When I re-programmed to simulate this- bingo! it illuminated. So a simple misinterpretation of the functions. Prob was I filled in large holes caused by the boiler installation the day before and convinced myself that I had inadvertently fouled a signal wire to the boiler. Anyway back on wall. Returned replacement for full refund. Nil cost only lots of time wasted but thanks to all who responded and your good self.

Thanks for the update and glad all is now ok.

 

[Jon Fredriksen]

I have the Honeywell st699 at home, on an oil fired boiler system, fully functioning BUT it only allows for both hot water and heating to run at the same times. I would prefer to be able to control both independently, as I require hot water at specific times. Am I able to simply upgrade the programmer to achieve this?

 

[king of pipes]

Only if you have a zone valves fitted a picture of the cylinder and associated pipework would help . Kop

 

[Mini Wael]

I have the Honeywell st699 at home, on an oil fired boiler system, fully functioning BUT it only allows for both hot water and heating to run at the same times. I would prefer to be able to control both independently, as I require hot water at specific times. Am I able to simply upgrade the programmer to achieve this?

I have the same problem with mine and I just moved in to new house has this device. I tried everything but it still works for both of them at the same time.
Please if you could find the solution for this advise me what to do.

Thanks