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.

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

I bought this Honeywell ST9400C programmer to replace an older malfunctioning ST9400C, this is an easy swap with no wiring to disconnect as the programmer just plugs into all the wires which are fixed on the original back plate. Heating back up and running now so all good.

Was easy to install.

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.

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)!

Good quality and easy to fit