Honeywell CM901 Room Thermostat Product Code: 39124

Electronic sensing element. 3-wire installation. Override facility. Holiday mode. Automatic BST/GMT time change.


  • Digital Display
  • 6 On/Off Periods per Day
  • 1 Pre-Set Programme
  • 24 Hour Programmable
  • 3 Wire Installation
  • Frost Protection
  • Override Facility
  • Holiday Mode
  • Automatic BST/GMT Time Change
  • 1 Year Guarantee


Switch/contact rating: volt free (switches 24-230V). Temperature range: 5-30°C. H x W x D: 89 x 133 x 26mm. 2 x AA batteries supplied.
Additional Information
Technical Specification
  • Brand : Honeywell
  • Manufacturing Standards : Building Regs Compliant,
  • Product Height : 89 mm
  • Display Type : Digital Display
  • Product Type : Room Thermostat
  • Programme Facility : 24 Hour Programmable
  • Zoning Level : One
  • Central Heating Control Type : Thermostats
  • Total Product Weight : 0.21 kg
  • Model No : CM901
  • Product Width : 133 mm
  • Temperature Range : 5-30 °C
  • Product Depth : 26 mm
  • Pack Size : 1
  • Installation Type : 3-Wire Installation
  • Compatible Boiler Type : All Boilers
  • Manufacturer Guarantee : 1 Year Guarantee
  • Pieces in Pack/Case : 1
Product Contents
Delivery & Returns


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€83.95 Incl. 23% VAT

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Honeywell CM901 Room Thermostat is rated 4.1 out of 5 by 20.
Rated 2 out of 5 by from 1 year warranty, lasted 1 year Display elements now missing and temp sensor reporting room temp of 10 ° rather than 18°c. Looking for replacement with a longer warranty.
Date published: 2017-06-10
Rated 5 out of 5 by from Excellent temperature control I used this to replace an old mechanical thermostat. Only took 10 mins to fit. Programming is very easy - the on-screen messages are excellent. I especially like the Optimization feature - very clever!
Date published: 2017-02-24
Rated 2 out of 5 by from Unreliable Unlike the other reviews, I could not recommend this unit I have had two of these and both failed for the same reason - garbled displays. I noticed that one of the other reviewers bought a second one because the first lost digits on the display. While it worked it was OK, though too fiddly and complicated to set up with features that most folk wouldn't use. Unfortunately, as usual, both were outside the short 12-month warranty.
Date published: 2016-11-07
Rated 5 out of 5 by from Excellent performance I bought this thermostat as a replacement for an identical existing unit. The previous one started losing some parts of the characters on the LCD display after 5 years service. Despite this, I bought another one simply because the performance of this thermostat is in my opinion the best for demostic application. My house tempreture is spot on the set desired temperature and always comfortable summer or winter (no overshoot). I tried different makes and types and this model has been outstanding. I have a Heat Pump heating system all the year round with back up Gas Boiler boost during the very cold periods. The CM901 has a features which control the heat pump's on/off cycling to its optimum working performance. The same exist for the gas boiler.
Date published: 2016-09-23
Rated 5 out of 5 by from CM901 Room Stat No frills room thermostat. Simple to install. Looks very tidy and has a large LCD screen so even in the dimmest light its easy to see. For the price, it's a good piece of kit.
Date published: 2016-06-17
Rated 4 out of 5 by from Honeywell CM901 Bought this to replace a Randall timer which had a permanent live / neutral to operate the timer linked to a switched live to operate the boiler. Just put the permanent live into A and the switched live into B, left the neutral and earth in connectors. Easy to programme / modify the built in programme. Worked straight away, now just need to wait to see what settings are best and if it is reliable.
Date published: 2016-05-30
Rated 1 out of 5 by from Honeywell CM901 Room Thermosta Our Honeywell basic analogue thermostat in the hall had been playing up, so decided to upgrade it to this digital one. My man took the old unit off and replaced it with the Honeywell cm901 unit. Wired the unit up as per the instructions and switched the power on and the fuse in the central heating system blew . Got in contact with Honeywell (the phone number in there supplied instructions is wrong - should be 0345678999) and then proceeded to wait for a representative for 15 minutes (should have told me something). Went through the wiring with him and he said it was correct, then asked him why the fuse was blowing and he said that it shouldn't and then said that I should get another electrician to check my wiring in my house. I told the representative the only change was the new unit to which he replied that I still should get another electrician to check my wiring in my house. I then returned the unit and got Drayton Digistat +2 Room Thermostat product that works without blowing my fuses
Date published: 2016-01-20
Rated 5 out of 5 by from Honeywell cm901 My regular heating man is mown out with work at present so could not attend. I decided to tackle the job myself. Our British Gas basic analogue thermostat in the hall has been playing up for a while. It is the type you turn the knob, you set it at a temp and it is supposed to keep heat constant. It wasn't, it was ramping the temp up to phew, then letting it drop to brrr. Measured the unit size to make sure the new decorations weren't spoilt. Took old unit off wall. Found the twin and earth feed. Put red into "a" and black into "b". It's a double insulated unit so earth not needed so taped off. Fastened back plate to wall. Put batteries in front part, and stuck the " how to" label inside lid. Clicked it into back plate. Read, and followed the instructions, off it went. Yes it makes a light click noise when the contacts operate but it does a verrry good job of keeping the temperature stable all day. It adjusts the radiators in litle stages, not achieving phew and brrr. We are retired, so each day is similar, therefore this unit is ideal. Anyone who works / is out during week would be better getting the seven day unit, so they could programme it for different days.
Date published: 2015-11-28
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