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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
  • ERP Control Class: IV
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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.

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Honeywell CM901 Room Thermostat Instruction Manual



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Rated 1 out of 5 by 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 20 Jan 2016
Rated 5 out of 5 by 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. 28 Nov 2015
Rated 3 out of 5 by Digits fail Had this for 2 years and now half the digits have failed. Can't tell the difference between a 7 8 or 9. Reliability very poor score. 6 Oct 2013
Rated 5 out of 5 by Excellent Product I installed one of these at home and working great. The TPI control "ramps" down the boiler time as the temperature gets close to set point. Less overshoot and a more stable house temeperature. Night setback and holiday mode are good. I am about to fit these and the DT90E to some fan convectors at work with old 2-wire thermostats with wide overshoot / undershoot of temperatures. Best feature of all for a School enviorment is being able to set the Max / Min adjustments within the installer mode which should prevent the unauthorised adjustment of the settings. Scewfix should consider stocking the CM907 unit as well for anyone wanting a 7 day version. 16 Oct 2011
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Download more info (pdf)

Brand Honeywell
Display Type Digital Display
Installation Type 3-Wire Installation
Manufacturing Standards Building Regs Compliant,
Model No CM901
Pack Size 1
Product Depth 26 mm
Product Height 89 mm
Product Type Room Thermostat
Product Width 133 mm
Programme Facility 24 Hour Programmable
Temperature Range 5-30 °C
Total Product Weight 0.21 kg