HONEYWELL ST9400C Thermostat Programmer. 7, 2-Channel, 3 on/Off per Day, 24 V, White, 1
Original price was: £95.00.£90.99Current price is: £90.99.
Price: £95.00 - £90.99
(as of Jun 10, 2025 14:35:10 UTC – Details)
The ST9400C in a 7-day Electronic Programmer which provides accurate time control for central heating systems with separate programmes for heating and hot water. ST9400C is suitable for replacing a wide range of programmers on the market and is a direct replacement for Honeywell ST6400 Programmers without the need for re-wiringThis Version replaces some of the following previous Honeywell Models: ST6400C1003 ST6400C1052.
St9400 programmers can be combined with other Honeywell Controls such as Room Thermostats, Cylinder Thermostats, Wiring Centres and Zone or Diverting Valves to form a fully automatic central heating control system.
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Any circuit boards cannot be returned if seal has been broken as incorrect diagnostics could cause damage to these parts.
Now with LoT Technology
Our Largest ever Backlight Display
Factory set Clock
Automatic Summer/Winter time change
7 Day or 5/2 Day operation
Product may comes in white box or plastic package
Customers say
Customers find the thermostat easy to install, taking just 5 minutes to replace the old model, and appreciate its functionality, with one customer noting it works correctly straight away. The device fits easily on the previous backplate and provides good value by saving on operational costs. They praise its control capabilities, allowing independent control of hot water and heating, and appreciate its versatility as a programmer. While many customers consider it a good replacement for the ST6400C, some report it being prone to failure.
8 reviews for HONEYWELL ST9400C Thermostat Programmer. 7, 2-Channel, 3 on/Off per Day, 24 V, White, 1
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Original price was: £95.00.£90.99Current price is: £90.99.
G McLaughlin –
Replaced old unit in a matter of minutes
Genuine part and so easy to set upI had to replace the existing controller because the buttons became “tired” and matter how hard I pressed I decided to bite the bullet and buy a new unit.I didn’t even have to set the clock because it had retained the time and date in the memory.The buttons are working fine now. I should have replaced it sooner and saved myself a few months of grief!
Rajul Patel –
Great replacement for the Honeywell ST6400C – Easy and simple to install and programme.
I brought the ST9400C to replace the ST6400C which had seen better days. The ST9400C is a direct replacement for the ST6400C and as such has been cleverly designed to sit on the same back plate as the ST9400C. This means no need to rewire, drill new holes or the need to call a plumber. All you do slacken two securing screws at the bottom of the ST9400C hinge the unit up to separate the backplate and main body of the ST9400C into two halves. You do the same process on the ST6400C, switch off your electricity supply at the mains and simply fit the ST9400C main body onto the existing ST6400C backplate. It is as simple as that, jobs done, hassle free and quick.The ST9400C unit comes complete with a simple to follow âquick programming guideâ which really makes light work of programming your hot water and heating needs. From start to finish I had replaced my old ST6400C with the new ST9400C and programmed it in no more the 15mins. I love the fact that the ST9400C even adjusted itself when the clockâs went back for winter.If I had to criticise anything it would be that the buttons do sometimes tend to stick behind the plastic body of the ST9400C, however pressing the buttons delicately seemed to solve the issue. I highly recommend the ST9400C. I have read issues about reliability of the ST9400C but since installing the unit about a month ago I have not had a single problem.
SP –
User friendly, good features
When I moved into my home the programmer that was fitted was a Horstmann. These repeatedly failed on me and when I tried to buy the replacement the model number had been discontinued. In the end I asked my brother for an economical alternative. He suggested the Honeywell ST9400C. It meant changing the back as well as rewiring which you could potentially do yourself if you know a little about electrics but if in doubt always check with a qualified electrician. It would be a really quick job so shouldn’t cost too much to get done.The Honeywell has proved to be so much better than Horstmann. The interface is more user friendly, the display is more informative and you have a few more controls and features such as override, extra hour, clearly lets you know when the next time its due to kick in etc. There were no problems installing and I’ve had no issues with using it so far. I’d definitely buy this brand again in the future for other houses.
Family Lavisse –
Brilliant
Brilliant. – worked straight out of the box – a life saver – simple easy to follow instructions
Richard Mills –
Bringing Warmth Back To A Frozen House!
Bought as a replacement for a simpler (and possibly even prehistoric) Honeywell controller that had died rather suddenly after many many years of service (and left us without heating or hot water until we figured out the problem).The controller is simple to install (I used a wiring chart that I found online that detailed how the wiring on the new controller related to the wiring on the old controller) and even simpler to operate. The LCD screen is bright and clear and informative – the default setting is to have the screen lit, but it will remain lit at all times (a little disconcerting initially). There are a host of settings that can be tweaked (including whether the LCD display is lit or not), and even the programming of the device is simple, making it easy to have different settings for each day or to copy the settings from one day to the next. There are even built in programs that you can use if you don’t want to set your own.Simple to use, not unpleasant to look at, quick and easy to fit (at least as a replacement) & (so far at least) reliable.
Joseph K. –
Finally a working heating and hot water system again!
I had an old ST9400S which would no longer function as the relays kept clicking and it was turning on and off every two seconds, meaning the system could never reach temperature. Tried temporary fixing by turning the backlight off and making heating and hot water come on at different times but eventually stopped working all together.Read somewhere on the Honeywell forums that the ST9400S and ST9400C used the same backplate so decided to purchase this as offered more programming and was cheaper. Installation was relatively pain-free apart from having to dremel off some of the plastic at the bottom as I do not have it mounted flush but rather with a wire running up the wall in the boiler cupboard. Ensured safe installation by turning off the mains as well.When turning mains back on, immediately came on with right date and time and immediately fired up the system again. Home back up to temperature and nice hot water; perfect!
Sue G –
Easy peasy to fit as a replacement to the st6400c
Simply turn off the power at the fuse box, undo two screws and snap out the old unit from the backplate, click in the new one and tighten up the screws again and put the power back on. Job done. 15 minutes tops, including opening the box and fetching the screwdriver.Well done Honeywell. What a clever design.
TichAmazon Customer –
Do not get this if you are not a computer geek with good eyesight.
Compared to my previous Honeywell programmers, with easy to use sliding switches, this is much more attractive……and that is where the improvement ends! It is so difficult to set, unless you want to leave the same settings every week, all year, that we just use the “extra hour(s)” feature all the time and never set it to auto. OK, I’m not young, and my reading vision is poor now, but I’m not the only one by any means who will find this fiddly and exasperating to use with b…r all advantage over the previous units (except that it is so bright you don’t have to turn the light on in the same room)!