48kwh per day for 2 hours heat!!!

WestonDave

I'm lost! If it sometimes calls for heat at 16.5 when set for 16, and its now not calling for heat at 16 when set for 16.5, its seriously screwed up and needs replacing. It can't be fixed so you need to decide whether this boiler cycling is worth paying someone to supply and fit a new stat.

My guess is that the amount of gas the boiler is using during these mini cycles is so small that if you watched your meter during these spells you wouldn't notice any movement.

Which brings us back to the real issue of your 48kWh per day consumption which is the fact that you are heating your lounge to 21C rather than 18C due to the temperature difference between the hall and lounge (probably as there are radiators in the lounge and none in the hall). Changing the stat won't change that differential between the two rooms so if you get a new one and set it to 18C and keep heating the lounge to 21C, you won't see the bills go down.

becksfaz

WestonDave wrote: »

I'm lost! If it sometimes calls for heat at 16.5 when set for 16, and its now not calling for heat at 16 when set for 16.5, its seriously screwed up and needs replacing. It can't be fixed so you need to decide whether this boiler cycling is worth paying someone to supply and fit a new stat.

My guess is that the amount of gas the boiler is using during these mini cycles is so small that if you watched your meter during these spells you wouldn't notice any movement.

Which brings us back to the real issue of your 48kWh per day consumption which is the fact that you are heating your lounge to 21C rather than 18C due to the temperature difference between the hall and lounge (probably as there are radiators in the lounge and none in the hall). Changing the stat won't change that differential between the two rooms so if you get a new one and set it to 18C and keep heating the lounge to 21C, you won't see the bills go down.

Flame light still off.... Just double checked settings. Set to 16.5, currently displaying 16c. When I explained the inaccuracy of the thermostat to BG engineer 2 weeks ago, he said 'they aren't always accurate, they are just a guide...' That comment was amongst other drivvel he had to say.
BG only replaced the stat in January - not sure they will give me another one(?)
I have watched my meter during these cycles and it uses 0.1-0.5 of a unit, which does add up when it boosts in and out the way it does.
We do have rads in the hall - there are 2 downstairs and 1 upstairs.
I wouldn't be setting a new stat to 18c cos I'm now aware of the temperature difference as you say. I just want to stop the boiler cycling when there isn't a need.

becksfaz

Was just vacing hall - heard stat click at 13.53pm, still displaying 16c, clicked out again at 13.58pm.

jalexa

becksfaz wrote: »

When I explained the inaccuracy of the thermostat to BG engineer 2 weeks ago, he said 'they aren't always accurate, they are just a guide...'

IMO that is an ignorant comment by the BG "engineer". They may (or may not) be "accurate", but there is no reason why they should not be be repeatable. The symptom you describe is unreasonably low hysteresis. That is a fault (unless it is a result of internal settings). Is there any mention in the instructions. I believe you have a re-badged Drayton. Can you identify the Drayton model?

grahamc2003

The stat should obviously maintain a differential between calling for heat and then not calling for heat. If the set temp is 18, then it should call for heat at say 17.5, and keep the heat on until a temp of, say, 18.5 is reached, then turn off until the hall cools to 17.5 again. It shouldn't be rapidly swithching on and off when at 18. Is the differential programmable, and set to zero?

Imv, the op shouldn't bother with what temperature the stat is displaying. Simply, if it's generally too cold, set the stat up 0.5, then leave for a few hours, still too cold up a notch more.

The differential between the hall and the living room could be solved with thermostatic valves I believe, so the amount of heat delivered to the lounge is reduced (assuming the op doesn't want it 21 in the lounge when it's 18 in the hall). The differential between the lounge and the hall can then be controlled.

becksfaz

jalexa wrote: »

Can you identify the Drayton model?

Googled Drayton and looks exactly like the Drayton digistat +3.

Just had a quick read of some reviews and theirs talk of some sort of 15 minute cycle and the fact that the boiler 'predicts' heat loss or something, which is why it kicks in when set to temperature.

I'm still slightly baffled though. If someone look into it and report back to me, explaining in English, I'd be REALLY grateful.

Read a couple of comments about people that replaced their stat - I am prepared to do this. For the peace of mind if nothing else. Please let me know your thoughts and recommendations.

jalexa

becksfaz wrote: »

Googled Drayton and looks exactly like the Drayton digistat +3.

Can't see any relevant setting in the Digistat +3. There is an "Intelligent Auto Start" mode (has to be selected) but I don't believe that would cause the problem you describe.

One thing that could cause the problem (other than being faulty) is being close to a radiator?????

Separate from the question of being faulty (or not), IMO a hallway is not a good location to accurately control the temperature of the largest/warmest/most occupied room. Unless rewiring to the living room is practicable then think about a wireless stat. However thick walls to the garage might affect the signal.

As to brand, a bit like Ford vs Vauxhall i.e. personal preference, but I have found Honeywell stats excellent.

becksfaz

jalexa wrote: »

Can't see any relevant setting in the Digistat +3. There is an "Intelligent Auto Start" mode (has to be selected) but I don't believe that would cause the problem you describe.

One thing that could cause the problem (other than being faulty) is being close to a radiator?????

Separate from the question of being faulty (or not), IMO a hallway is not a good location to accurately control the temperature of the largest/warmest/most occupied room. Unless rewiring to the living room is practicable then think about a wireless stat. However thick walls to the garage might affect the signal.

As to brand, a bit like Ford vs Vauxhall i.e. personal preference, but I have found Honeywell stats excellent.

Reading the reviews on screwfix, it's got some sort of build in thing, it begins with an a..... can't remember the name (that cannot be over-written) that cycles the boiler frequently. Someone said that if you are a person who leaves the heating and boiler on 24/7 but has it on stat control, the boiler will continue to fire all of the time. Another has said that it 'learns' the warm-up and cool down of your house so will sometimes call for heat over temperature predicting heat loss and sometimes not call for heat below.I can't de doing with that!
For some like me who is in the house with the little one and last year (after my big bill with my heating controlled 24/7) set the heating to come on at 6.30am and go off at 9pm - it means that with this stat, the boiler will constantly be firing regardless of it reaching my temperature! This stat is not for me....
..... and it's a relief to know that I haven't been going insane all this time!!!

jalexa

becksfaz wrote: »

Reading the reviews on screwfix,

Interesting, particularly "meerkat's". I recognise the heat "top-up" feature described. Probably all modern electronic stats have it including the Honeywell CM907 which I have, but I have never experienced the "Drayton" behavior. Neither did my previous Danfoss behave that way.

There is one thing which may be exaggerating its behavior with you. If the hall cools quicker (than the living room) then more heat "top-up" will be required. Based on your report (and Screwfix reviews) ISTM that the Drayton is not so much "faulty" as "flawed".

Normally a little "top-up" would be less of problem as the heat would be "lost" in the house. If your boiler is in the garage then more of the heat gets "lost".

Probably no easy, as in cheap, solution. Still think the hall is not the best location. Did you answer if a radiator was near?

becksfaz

jalexa wrote: »

Did you answer if a radiator was near?

Oh no sorry. Not really. There are 2 rads in the hall. I've just 'paced' them - one is 7 paces away and one is 5 paces away.
The hall rad at 5 paces is the last rad in the system so I don't think it's a case of the rad getting hot and kicking the stat off.
We have a large system (14 rads, currently operating 11) so when the stat kicks in, it takes approx 10-15 mins for the rads to even get luke warm.