Honeywell ST9400C Programmer. 7, 2-Channel, 3 on/Off per Day, 24 V, White - Bulk Package

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 ‘quick programming guide’ 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 clock’s 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.

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!

I needed a replacement timer for my old timer which had given up after 20 years service. The instructions were clear as to the changes to the wiring needed as the back-plane wiring was different to the old one. I slipped numbered sleeves (not supplied) on to each wire as I removed it from the old timer which recorded which terminal they would go into the new unit. The size of this unit was slightly smaller than the old timer, and I had a cut an additional wall tile to fill the gaps left. This by far the most fiddly part of the process. The timer can be configured to have same time every day, same time Monday to Friday and different time on Weekends, or different time every day. The 'holiday' facility also looks handy, but not yet tried. This allows the timer to come after several days of non-activity, so that you can come home to warm home after being away. Only downside I foresee is that this won't allow a bare minimum of heat to be kept on to stop freezing whilst away. Overall I am pleased with the purchase, and have no regrets.

Brilliant. - worked straight out of the box - a life saver - simple easy to follow instructions

Good quality and easy to fit

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.

Great controller the only critisiscm I have is how difficult it is to get to the retaining screws underneath the unit to secure it to the backplate

This is an excellent programmer, easy to set up, particularly for holiday settings. HOWEVER I have had to replace the unit twice since my system was installed just over three years ago. In both cases it failed to activate the hot water, although the central heating worked OK. I suspect that this was due to relay failures. A saving grace is that it is easy to replace, once you understand how it plugs in to the baseplate.