Is average gas usage really 12,000kWh? I use 40,000!

Gerry1

StillNotRich said:

The meter measures M3 and that corresponds with the bill. I did a quick test where I turned up the heating to max when the boiler was cold and measured the amount gas used over a few minutes, it worked out at 39.9kWh which I believe is correct for a 40kWh boiler.

The only explanation I can think of is that the average usage quoted is wrong or that there's something wrong with my boiler - the meter seems fine but I might be missing something.

Welcome to the forum.

Yes, you are missing something, you're getting your units mixed up, confusing power with energy.  This may lead you to draw wrong conclusions.

The boiler is a big one, with a rated output power of 40kW.  If run for an hour at full power it will use 40kWh of energy.

However, in reality will will switch off or modulate down to a lower power when the house has warmed up.

Your test lasted only a few minutes so the instantaneous power may well have been 39.9kW but it's unlikely you used 39.kWh of energy in a only a few minutes.

MWT

StillNotRich said:

The temperature is relatively high, set to 21deg usually (my wife!) the water is not particularly hot, the boiler dial is set in the middle (it doesn't show a temperature) and the hot water tanks (there are 2 for some reason), are at about 68deg. We usually have showers, not baths, but we run the dishwasher daily and the washing machine twice a week....

As the others have said, you have the causes of your high use right there.

The good news is that the changes are easy to make and it seems likely you already have all the necessary controls fitted to let you make a considerable saving over the next year.

Do have a closer look at your smart controls and consider setting schedules that will vary the target temperatures across the day, so for example you warm things up for the early morning period while people get dressed, then drop down to a lower temperature for the majority of the day while people tend to be more active, then warm up again in the evening when things slow down again before dropping the temperature over night.

For us that typically means around 19C in morning for a couple of hours then down to 17C during the day, up to 20C for the evening and then down to 16C overnight.

As long as your insulation is decent the odds are it will never actually drop as low as 16C overnight.

Do check the controls for an option between 'comfort' and 'economy' ...

The difference is that comfort will make sure the temperature reaches the set-point by the start of the time period, but economy will avoid using the heating if you are close to the required temperature and will stop using it earlier than the end of the period when it learns how fast things cool down.

'Comfort' setting becomes a luxury with prices as they are  

chris_n

While 21 may be slightly on the high side I don't think it's excessive, I would be having a serious look for air leakage if your insulation is as good as you say. You can have all the insulation you want but if you let warm air out  and cold air in it is worthless. Agree with Gerry1 you might need to revisit your test and get your units sorted out.

BobT36

I personally turn my heating on only when it's needed, and that's for what, 4-7 days out of the year when it's really bloody cold? 
I then turn it straight back off, once the rooms have warmed up (heating only the rooms with people in). 

The rest of the year, pop on a fleece jacket or warmer socks. If you want to sit around in shorts and a t-shirt with the heating on full blast all year round, of course it's going to be costly... 

theoretica

25kWh for just water will be maybe 300litres of hot water a day - do you use about that?  If not it seems a useful target to look at.  Starting with WHY do you have two hot water tanks, can they be heated separately, are you using both, do you need both?

markin

Are the tanks modern with insulation?

Zandoni

Can you post a picture of your gas meter?

Cardew

Robin9 said:

Do check the meter details 

Is the meter marked as ft3 or m3
Ditto the bill

What is the serial number on the meter
Ditto the bill

OP states in first post: 'The meter measures M3 and that corresponds with the bill'.

StillNotRich

theoretica said:

25kWh for just water will be maybe 300litres of hot water a day - do you use about that?  If not it seems a useful target to look at.  Starting with WHY do you have two hot water tanks, can they be heated separately, are you using both, do you need both?

I'm actually wondering if that might be the problem - it seems one of the tanks is only used for the family bathroom which we rarely use. We noticed in the past that if the boiler brakes down or we forget to switch it on there is always hot water in that bathroom. The emersion heater is not plugged but were still keeping an entire tank warm without actually using it that much - I'll get onto my plumber.

StillNotRich

Phlik said:

StillNotRich said:

Thanks all for your responses.

The temperature is relatively high, set to 21deg usually (my wife!) the water is not particularly hot, the boiler dial is set in the middle (it doesn't show a temperature) and the hot water tanks (there are 2 for some reason), are at about 68deg. We usually have showers, not baths, but we run the dishwasher daily and the washing machine twice a week....

Cheers

Running your house at 21 °C will be the issue. Is the boiler set to maintain temperature throughout the day/evening, or on and off for set periods?

It sounds from your first post like the heating either upstairs or downstairs is on through most of the day/evening. If you want to maintain 21 °C throughout the day then it's going to cost, a lot. For me 21 °C is way too hot and I get irritable and not due to the cost

This may well be the case, I've always known we keep it high but I didn't think it would make that much difference...

I can see looking back about 7 or 8 years ago when our kids were very young that we used a bit more gas but not much more - at that time my wife insisted on having the heating on all night and day so I assumed it would cost much more.

Anyway I'm sure this is good advice.