Honeywell CM927

new_owner

OK needed to put in a wireless thermostat while decorating.

So I opted for the Honeywell CM927. Now I am struggling with the timer

All I want is it to come on at 5:30am for 30 mins at 18 degrees and then switch off again then do the same at 6pm at night.

I dont want it to decide when it will switch on or off.

Is the best option to turn off the optimise option?

or set the 6 time to;

1 = 3:00 am 6 degrees
2 = 5:30 am 18 degrees
3 = 6:00 am 6 degrees

or do you need to be more exact

1 = 5:20 am 6 degrees
2 = 5:30 am 18 degrees
3 = 6:00 am 6 degrees

???

Damn thing

keithu

1 - 5.30am 18 degrees
2 - 6.00am 6 degrees
3 - disabled
4 - disabled
5 - 6.00pm 18 degrees
6 - 10.00pm (?) 6 degrees

You disable a step by pressing and holding the 'i' button.

The optimise function only applies to step 1 and would turn the heating on earlier to bring the temperature up to 18 degrees by 5.30 in this case. If you want the heating to come on at 5.30 on the dot you should disable it.

macman

The optimiser is disabled by default, to switch it on you need to access the installer menu.
The optimiser function is OK but it only works on the data stored from the day before, so sudden ambient temp shifts overnight will fool it.

daveyjp

Depending on the room temp and property insulation half an hour may not be enough to get to 18 degrees.

No need to skip times, just set up 1,2,3 and 4 as per keithu settings.

Mr_Ted

All an Optimiser is is a weather dependant time clock!
For an Optimiser to work correctly it needs an external temperature sensor and an internal temperature sensor, ONLY if this is how it is connected will it work correctly and this will mean it will evaluate the outside and internal temperatures to give the set temperature in the property as per the time and temperature settings, it will if setup correctly also Optimise OFF so you will not be using any more fuel, but probably will save fuel!

Is this the way the system is installed is what is needed to assist?

If it isnt, why spend the added cost of using this type of controller rather than a simpler controller!

stevemcol

Give the optimiser a try, it's a good feature. Agree it's not perfect becuase it doesn't know the outside temp but it's pretty good at hitting the target temp on time. I've experimented a lot with different heating / thermostat settings. I find that the optimiser uses less gas than other methods. I've been at home during the day and noticed it coming on in time for 'home time'. Doesn't come on too early and has the house up to temp bang on time.

If you're not bothered about having the house warmed up when you get home, then I agree, don't use the feature.

new_owner

Thank you.

All working now.

@mr Ted; Bought because honeywell have a good name and I was in a hurry I am not sure the Optimiser works to that level. It looks like it works off the room temp. There was not really a price dif between this and the model down..

Just so used to a stop start timer it had me a bit thrown when the temp failed to go off

@stevemcol; I will try it once I have got used to the system. Seems to get mixed reviews.

Thanks all again

macman

I don't think that even if you fit the optional external temp sensor it links with the optimiser function. The optimiser just 'remembers' how long it took to get to the set temp from morning start up the day before, and adjusts the start up time accordingly.
The external temp sensor is just 'for information'. If it does link to the optimiser, then nothing in the documentation states that to be the case.

Mr_Ted

:rotfl:

macman wrote: »

I don't think that even if you fit the optional external temp sensor it links with the optimiser function. The optimiser just 'remembers' how long it took to get to the set temp from morning start up the day before, and adjusts the start up time accordingly.
The external temp sensor is just 'for information'. If it does link to the optimiser, then nothing in the documentation states that to be the case.

:rotfl:Sorry but its a common deficiency in this country for domestic installers lack of knowledge on optimisers, or compensators!
An optimiser needs the outside sensor to calculate, in real time, when the properties heating, sensed by the internal sensor, will reach the desired set temperature!
It needs the external sensor as it is external temperature that determines the internal temperature when the heating ISN'T ON, i.e. obviously if its very cold outside it will cool the property much quicker and require more heat to bring it back to desired temperatures, the optimiser does this automatically for any given external conditions!
It requres 2 inputs to evaluate the 1 output required to reach that desired property set temperature and to assess the timing for heating On, or heating Off!
i.e. it calculates how long before the set times in the controller it is required to bring the heating on to reach the set temperature at the desired time the temperature is required!
It also does the reverse for the desired OFF time by calculating when to turn the heating OFF and still have the desired temperature for he SET off time!

It has nothing to do with remembering the previous days activities, as they could be totally different day by day, and as i say it uses information to evaluate the given conditions in real time!

stevemcol

Mr Ted. I counted 7 exclamation marks! I didn't think room stats could be that exciting.

The CM927 does seem to do a pretty good job of predicting the house warm-up profile though, without knowing the OAT.

All stats, works best if fixed in a communal area (hallway) and the rad in that area mustn't be rad stat controlled. It predicts the warm up rate well and maintains the home's core temperature whilst individual rooms can be regulated with rad stats.

With wireless stats, people do make the mistake of moving them around the house, which is never going to provide effective control.

I live in an exposed 3 bed corner semi and my combined fuel bill is less than £1k p.a. When the house is occupied I always set a target 19° which will be achieved when we get home from work, without significant waste.

macman

Mr_Ted wrote: »

:rotfl:

:rotfl:Sorry but its a common deficiency in this country for domestic installers lack of knowledge on optimisers, or compensators!
An optimiser needs the outside sensor to calculate, in real time, when the properties heating, sensed by the internal sensor, will reach the desired set temperature!
It needs the external sensor as it is external temperature that determines the internal temperature when the heating ISN'T ON, i.e. obviously if its very cold outside it will cool the property much quicker and require more heat to bring it back to desired temperatures, the optimiser does this automatically for any given external conditions!
It requres 2 inputs to evaluate the 1 output required to reach that desired property set temperature and to assess the timing for heating On, or heating Off!
i.e. it calculates how long before the set times in the controller it is required to bring the heating on to reach the set temperature at the desired time the temperature is required!
It also does the reverse for the desired OFF time by calculating when to turn the heating OFF and still have the desired temperature for he SET off time!

It has nothing to do with remembering the previous days activities, as they could be totally different day by day, and as i say it uses information to evaluate the given conditions in real time!

Thanks for that info. So how does my CM907 optimiser calclulate the start up time, given that it does not have the external sensor fitted? It clearly functions without the sensor, as the start up time does vary quite widely.