Help with thermostat controller, costing too much

Nicky321

My mum has an Ideal Isar Boiler and a Honeywell CM61NG thermostat.

At the moment the boiler is coming on and going off as it pleases, this is turn is costing a lot of money.

Ideally she would like her central heating on 7am - 9am at a temperature of about 20 deg, then 12pm - 2pm at roughly the same temp and finally 6pm - 9pm again at 20 deg.

However I have turned off the optimum start but i cannot get it to work to the requirements above.

Please help, spent days searching the internet with no real success.

Johnandabby

The optimum start makes sure that at the time set in the programmer the house is at the right temp, ie if the start time is 7am, the optimum start will bring the boiler on at say 6.30am (time dependant on how cold the house is to start with) to make sure that the house is at the set temp at 7am. Most boilers don't have this, so people set the heating period longer to recreate the same effect manually. If you use the optimum start function, you then to make sure that you're not including the heat up periods twice - just have the time set for when you want the house to be at temp.

Have you set the times on the programmer correctly as per the times above? The programmer allows you to set 6 temp change times per day so should be ample for this.

DavidFx

so just to clarify

you have set

7am = 20 deg
9am = ? temp

12noon = 20 deg
2pm = ? temp

6pm = 20 deg
9pm = ? temp

If the ? temp is set too high then the boiler will fire to maintain this temp

Nicky321

Thankyou for your replies,

If the optimum start is off am I correct in thinking it will only switch on as follows:-

So if I set it at 7am = 20 deg (boiler switches on)
9am = 10 deg (boiler will switch off)

12pm = 20 deg (boiler switches on)
2pm = 10 deg (boiler switches off)

6pm = 20 deg (boiler switches on)
9 pm = 10 deg (boiler switches off)

(where the temp is set at 10 deg, only if the room temperature is below this would the boiler operate to bring the temp upto 10 deg?)

ValHaller

Nicky321 wrote: »

(where the temp is set at 10 deg, only if the room temperature is below this would the boiler operate to bring the temp upto 10 deg?)

Yes, the thermostat would ensure that the temp never dropped more than a smidgen below 10deg. This temperature is too high and I imagine that the boiler will still run several times each hour.. Try something like 3 or 4 deg C. You may need to start the heating earlier to allow for the colder start temperature.

DavidFx

The minimum temperature you can set is 5 deg C

loracan1

Is it an RF controller? or wired in.

Nicky321

loracan1 wrote: »

Is it an RF controller? or wired in.

RF i assume, its not wired

macman

When you say 'it comes on when it pleases', can you be more specific? Exactly when? Is there a pattern, or is it random?
If it's coming on during the night, then it's probably the frost 'stat function kicking in at around 5C to protect the boiler from freezing. Is it in a garage?
I have the optimum start function enabled on another Honeywell programmer, and in the recent very cold weather it's been kicking in at anything up to 90 mins before the 'official' start time of 7am.

Nicky321

YEah, sorted, set it as

7am = 21 deg (boiler switches on)
9am = 5 deg (boiler will switch off)

12pm = 21 deg (boiler switches on)
2pm = 5 deg (boiler switches off)

7pm = 21 deg (boiler switches on)
9 pm = 5 deg (boiler switches off)

just needs a little bit of tweaking now, maybe set it for 6.30am so its warm we mum gets out of bed.

THANKYOU TO EVERYONE WHO HELPED X