Honeywell thermostat query

stuomac88

Hi all

Completely clueless when it comes to thermostats so hoping someone here can help me.

I have a Honeywell CM907 7 day programmable thermostat. I have always used the manual function for the central heating, but we recently got a new puppy and the room where he sleeps can get quite cold so I wanted to set a programme for the heating to come on a few times a day to keep him warm when the heating would otherwise be off.

I have set the programme to come on at 7am, 11pm & 3am for all 7 days(all at 20C) I put the thermostat on auto yesterday to see if it worked and it just seemed to maintain a temperature of 20C constantly, not at the times I had set. For example it was about 9PM(2 hours away from nearest time on my programme) and our radiators were boiling hot, checked again at 10pm and radiators were luke warm but room temp on stat was constantly showing 20C.

Am I doing something wrong or is this how the programme works? It seems to me that having it on auto would cost a lot more than using manually if it maintains that temp 24/7.

Apologies if I’m being stupid here but it really has me stumped, thanks in advance for any advice.

All the best
Stuart

Flt._Lt._Biggles

I don't know the details of the thermostat, but you say you set the "on" times, but did you set any "off" times?

System

stuomac88 wrote: »

Hi all

Completely clueless when it comes to thermostats so hoping someone here can help me.

I have a Honeywell CM907 7 day programmable thermostat. I have always used the manual function for the central heating, but we recently got a new puppy and the room where he sleeps can get quite cold so I wanted to set a programme for the heating to come on a few times a day to keep him warm when the heating would otherwise be off.

I have set the programme to come on at 7am, 11pm & 3am for all 7 days(all at 20C) I put the thermostat on auto yesterday to see if it worked and it just seemed to maintain a temperature of 20C constantly, not at the times I had set. For example it was about 9PM(2 hours away from nearest time on my programme) and our radiators were boiling hot, checked again at 10pm and radiators were luke warm but room temp on stat was constantly showing 20C.

Am I doing something wrong or is this how the programme works? It seems to me that having it on auto would cost a lot more than using manually if it maintains that temp 24/7.

Apologies if I’m being stupid here but it really has me stumped, thanks in advance for any advice.

All the best
Stuart

As my wife often says to me 'try reading the user guide'.

Downloadable from here:

https://www.honeywelluk.com/products/Programmable-Thermostats/TPI/CM907-7-Day-Programmable-Thermostat/

The CM907 is a TPI thermostat which means that it is designed to keep the temperature with a 2C temperature range. If, say, you come down in the morning and there is a 5C difference between the actual temperature and what you have set within on the thermostat, then the CM907 will demand maximum flow temperature from your boiler. The aim being to get your house up to temperature ASAP. Once the temperature is within the 2C block, then the CM907 will calculate and inform the boiler of the amount of heat required to sustain the set temperature.

It follows that to keep your puppy warm, it might be more efficient not to turn your heating on and off but to set a lower minimum temperature when you are out.

I have remote monitoring of my gas usage (optical spot reader). I also have a TPI controller and my gas usage for the first hour in the day is high. For example, we used 1.3CM3s of gas between 5.30 and 7.30 am this morning to heat the hot water cylinder and get the house up to temperature. From 11.30 to 1.30pm, we have used just 0.4CM3s to keep the house within the 2C set temperature range. If I allow the temperature to fall outwith the TPI 2C range, then boiler max flow and temperature will be requested to get the house back up to the set temperature.

ThePants999

The way the CM907 works is that you don't program "on" and "off" times, you program what temperature you want it to be at what times. So if you set a schedule that looks like this:

0700 - 20 degrees
1000 - 10 degrees
1800 - 20 degrees
2100 - 10 degrees

then it will attempt to maintain the temperature at 20 degrees between 7 and 10, and between 6 and 9, and at 10 degrees at all other times. And you can set a different schedule for each day of the week. You're then just supposed to leave it on auto all the time, and it'll make sure that the house is warm when you want it to be. It's still energy efficient, and much more comfortable than the large swings in temperature you get if you just have the heating on full blast every now and again but entirely off in between.

matelodave

As said above a programmable stat isn't like a normal swith on/off stat. It needs to be programmed to tell it what temperatures to set at what times otherwise it will stay on all day.
an example
20 degrees at 0700 - temperature will maintain at 20 until 0900 (2hrs)
15 degrees at 0900 - then drop to 15 degrees until 1200 (3hrs)
20 degrees at 1200 - increase to 20 degrees until 1400 (2hrs)
15 degrees at 1400 - decrease to 15 until 1700 (3hrs)
20 degrees at 1700 - increase to 20 degrees until 2200 (5hrs)
10 degrees at 2200 - decrease to 10 degrees until 0700 next day (9hrs)

They dont actually switch off you just set a very low temperature if you dont want any heat. Once you've programmed it then the stat will continue cyccling through it's settings and controlling the temperatures every day. You can usually set 6 programe times for each day of the week or 5+2 where Monday to Friday are the same but Saturday and Sunday are different because you may be at home all day at weekends.

Another advantage of a programmable stat is that if you manually adjust the temperature for any reason, it will resync back to it's normal programme at the next switching time which saves it being adjusted and forgotten.

Learn how to use & programme it properly and it will save you money and keep you comfortable without manual intervention.