Honeywell 7-day Programmable Thermostat CM907 CMT907A1041

We used to have a Drayton Digistat 3, which was quite old and started to switch itself off leaving the boiler in its last state, i.e. on or off. I also found the Drayton incredibly complicated to configure over 7 days and I normally quite good with these sort of things.

The Honeywell CM907 is brilliant and much easier to use than the Drayton! I love the fact I can not set the room temp down to .5 of a deg, where as with my old thermostat I found 21 a little too cold and 22 a little too warm. I also love the "Day off" feature, so you set all your times up for the weekdays and weekends and if you are off during the week, you press the day off button and it runs Sunday's program, so you have a warm house all day. Also I like the party feature, so if you have friends over for dinner and run late past the heatings programmed time, you can press this button to make the heating run and extra hour, or set how long you want it to run, after which it returns to its normal times.

It is covered in easy to use buttons so you don't have to click through tireless menus to find what you want, one or two clicks and it is doing what you want it to do. It is packed with all sorts of features that will make your life easier.

Really easy to install, took me 20 minutes! Mine was connected to a Combi Boiler so all you have is two wires to hook up.

I highly recommend this product to anyone out there who either wants to update their existing programmable thermostat or wants to replace their thermostat with a programmable one.

I've had a Honeywell TP7000 7-day programmable stat for some considerable time, and whilst it was good it suffered badly from 'overshoot' i.e. if you set a given temperature higher than the current (for example in the morning for getting out of bed) you would absolutely roast as the stat kept the boiler running far too long. I ended up having to pre-judge this and set an initial lower temperature then a higher one at a later time which was a real pain in the backside.

The CM907 on the other hand is incredibly good at maintaining the right temperature, even with a difficult house like mine where it takes the boiler a considerable time to get things hot but there's then a lot of thermal mass so you get a lot of extra heat even after turning it off. The CM907's proportional control and the very configurable settings (proportional bandwidth, cycle time and minimum on/off times) allow you to tune it perfectly to your installation.

Combine this with the 'optimisation' feature by which the controller estimates how far in advance of your set time it needs to turn on to get the temperature right by that time, and you have an excellent solution that's dead easy to use despite the complexity hidden within it.

Aesthetically it looks great too, the display is stylish and easy to read and it's very easy to programme. It can handle any temperature you want for frost protection / holiday (unlike my TP7000 which was hardcoded to 8C - useless!) and it can handle days where you're at home instead of at work for example during holidays.

The one thing I would say beware of is if you're a shift worker - the CM907 assumes that your holiday days must be copies of Sundays, so if your working pattern is that Sunday has the heating down as you're normally at work then you'll find that's what it does when you tell it you're on holiday! Other than that relatively minor restriction I reckon this stat can handle just about any scenario, maintains temperature very well indeed even with difficult heating 'loads' and is dead easy to fit on a standard wall box.

Highly recommended. And cheaper than my TP7000 was too, so Honeywell have improved the product significantly AND made it cost less. How's about that!?

There have been a few comments regarding the cycling function of this controller - in so much that by default the controller has 6 heat cycles (6 x on/off) per hour. But what hasn't been pointed out yet is that the cycling only kicks in when the temperature is within 1.5°C of the desired temperature. (This is adjustable between 1.5-3.0°C in the installer menu.) So if you set the desired temperature to be say 22°C then the controller will be permanently on until the room temperature reaches 20.5°C at which point it will start cycling to reach the 22°C setting. The cycling is designed to optimise condensing combi-boiler efficiency and ensure that the set temperature is reached controllably and not exceeded. The default setting is 6 cycles per hour as is what is recommended for combi-boilers but you can adjust the number of cycles from 3-12 if you like. Of course if you're finding that the cycling is not allowing the heating to quite reach the preset temperature (in very cold temperatures) you can always set the temperature 1.5°C higher than the desired temperature to compensate and it'll not cycle. You can then add another program to set the temperature at your actual desired temperature and the cycling will be able to maintain it. For example: if I want the temperature to be 21°C by 8am I may set the heating to come on at 7am and set the temperature to 22.5°C. I may then set a program to change the temperature to 21°C at 8am and the controller will accurately maintain it. Once you learn how the cycling works you can exploit it as described and end up with a very accurately controlled heating system.

I also like that you can calibrate the room temperature - so if the temperature reading on the controller is a little off, you can adjust it to get it spot-on rather than setting the temperature higher/lower to compensate. Would buy again and recommend. Bought from a local plumbers merchant for £60.25.