Huge Gas Usage of 32,000 kWh per year - Help !

Herbyme

My house is 1980s, 4 beds, 3/4 adults WFH, 5 in total, ie 5 showers a day + everything else we use hot water for, washing up etc In the summer we only use gas for water heating, no cooking or heating. Our monthly usage is around 400KWh/month.

I do think our hot water cylinder could do with better insulation. Can't see why an old duvet or sleeping bag wouldn't be at least nearly as efficient as a purpose made thing, as long as I can get it to fit neatly and add an outer layer eg sheeting,, can anyone advise?

Also how do you know if a room would benefit from more underfloor insulation? I havea a big room above a garage, although to be fair the rads are very rarely on in that room, its occupant likes a cold bedroom. It was given an extra layer of ? chipboard type insulation under the carpet when it was laid ?16 years ago, maybe that's enough?

ManMadeWays

Herbyme said:

Also how do you know if a room would benefit from more underfloor insulation? I havea a big room above a garage, although to be fair the rads are very rarely on in that room, its occupant likes a cold bedroom. It was given an extra layer of ? chipboard type insulation under the carpet when it was laid ?16 years ago, maybe that's enough?

In this particular room there was filtration, you could see dust/dirt blown up round the edges of the carpet, also 1930s floorboards with large gaps and around the rad pipes. The carpet/underlay was old and worn. Around Easter I lifted the boards and put Celotex between the joists, being careful not to block the airbricks. Over the summer this was the coolest room in the house, so expecting a vast improvement over winter. That's a bit drastic DIY, but you can get insulating board/underlay/high tog carpet that helps.

Herbyme

ETA re post above - our usage is 400KWh a month in the summer. In the winter it's several times that obviously.

Also about temp in hot water tanks - mine says it's set on 50 but it's a tiny dial so it's impossible to read accurately - I can measure the actual max temp when it's been heated for a while and I run it off, but what about the temp it drops to between periods when it's being heated, I doubt it's above 50 for 2+ hours at a time (see thermometer infographic above). ? Do I need to worry about that re Legionnaire's disease?

pochase

michaels said:

Looking at your June and July Gas usage and lets assume you were there all June and 1/3rd of July and the difference is 320kwh.

This seems like if you had been away all of July the usage would be 440kwh (pro rata).  I would say this is an order of magnitude higher than it would take to keep your hot water tank at temperature.  I would guess that either you are loosing hot water all the time (dribbling tap or pipe leak) or that the heating is actually on for some reason.  Surely the pilot light can't use that much energy.  Could the boiler be cycling on and off very often when heating the water, using energy to get up to temperature and then immediately turning off again?

In terms of your actual hot water usage of 480kwh based on the June/July comparison, this looks about right to me, we have 5, 3 teenagers in the house and use more than this.

https://www.energuide.be/en/questions-answers/just-how-much-does-the-pilot-light-of-a-gas-appliance-consume-exactly/716/#:~:text=So a pilot light uses,year (for 250 m³).

It seems that over 200KWh per month for the pilot light is possible.

Consulting different sources, you come across stated consumption levels ranging from 60 m³ a year, all the way up to 250 m³.

FreeBear

Herbyme said: Also about temp in hot water tanks - mine says it's set on 50 but it's a tiny dial so it's impossible to read accurately - I can measure the actual max temp when it's been heated for a while and I run it off, but what about the temp it drops to between periods when it's being heated, I doubt it's above 50 for 2+ hours at a time (see thermometer infographic above). ? Do I need to worry about that re Legionnaire's disease?

As mentioned earlier, 200-250 cases per year out of a population of 67 million - The risk is very, very low.

BUFF

tiya1990 said:

2) theoretica : Thermostatic valves - We have this in the 4 bedrooms only -  : Its called Danfoss - photo attached - works intermittently in some rooms . Is this supposed to communicate with the thermostat ?- thermostat only in hall - 'Drayton Digistat + 2 ' as shown in photo- none in any other room. 
They are meant to switch a radiator on /off (when ch is running) according to room temp. so will appear intermittent. They are independent of the Drayton digistat.

BTW  - downstairs radiators are all covered by wooden radiator covers - would this affect the heating ?
Yes, exactly by how much will depend upon the design of both radiators & covers

3) Electricity : We do not have an electric shower / hot tub / pond pumps / UV lights / Sunbed / Air Conditioning.  One Gaming PC which is played on perhaps 6 hours a day in holidays and 1 hour a day during school time. We do have fridge freezer in the garage - and I am checking on the Power Meter for these.

your dhw tank presumably has an immersion (or 2) fitted as a backup. Is this by any chance switched on (we have recently seen this from another poster)? Especially important re. 4 below as it will probably be set to a higher temp.

4) FreeBear : I have turned down the thermostat at the hot water tank to 45 degrees after your suggestion .

5) BUFF : I think we need to go down the new boiler route in any case however I still wonder whether there is something else that we are missing that is accounting for such a huge gas usage. There are draughts through the doors and I wonder to what extent that is contributory. 
You do need to draughtproof but imo it's not likely to be a major component of your high usage.
As I previously mentioned I would take the opportunity of a new boiler to modernise/upgrade all your controls - properly used they will at the very least pay for themselves over the life of the new boiler.


6)  We do have an electric car which consumes 250kWh per month ie 3000 kWh per year. But the strange thing is that , our annual electric consumption without the car in 2020 was 9000 kWh and is now still 9-10,000 kWh which does not make sense !
Perhaps your energy saving has already started to bear fruit?

macman

Get the new boiler install booked before the heating season starts: the way gas price projections are looking, it could pay for itself in 2 seasons.
And please don't ask BG to install it: you'll pay maybe 40% more. Use an independent local RGI.

Dogbyte009

We used to have an Ideal Classic. Switching to a condensing system boiler - so keeping the hot water cylinder - cut the gas consumption by nearly a third.

xeny

Herbyme said:

I do think our hot water cylinder could do with better insulation. Can't see why an old duvet or sleeping bag wouldn't be at least nearly as efficient as a purpose made thing, as long as I can get it to fit neatly and add an outer layer eg sheeting,, can anyone advise?

It'd insulate OK, not sure if there is any reason why it would be a bad idea. Screwfix are doing the purpose made thing for about £15, which isn't too bad.

Tarmacexpert1962

Its 100% that boiler - Had exactly the same issue as you a year ago and was using 32,000kw pa on Gas with an old but well serviced 19 year old (20KW)  British Gas Boiler that was struggling to heat our extended 4 bed 2,000 sq ft detached house - 1930s with Cavity Wall and Double glazing throughout - The new Worcester Bosch boiler has literally halved our Gas usage to about 16/17,000 KW and only cost £2850 to install, so at current rates it will have payed for itself within a year, I have been truly amazed at how much more efficient it is and with a 32kw output its 50% more powerful than our old boiler so the house is actually warmer. I do run Google Nest so thats also very good at making sure its efficient, last Winter made sure the house was running at 20 Deg and then tweak it down a little during the day and up a bit until 10pm. Thermostatic valves on all our rads help as well. Also added more lagging to the insulated HW Cylinder, massive benefit on that as stays hotter so much longer and now just an hour a day gives a full tank of Hot water using only about  6-7 KW in Summer months. My wife and I work from home as well so just like you we were using 6000Kw of Electricity per annum and I have managed to halve that by turning off all the Phantom gadgets, changing an old 10 year TV to an efficient 43" model  plus we had an old Freezer in the utility room guzzling 40kw a month and not needed daily - Our other Liebherr Kitchen Fridge Freezer is 18 years old and uses 2kw a day (Power meter checked) so thats still a big culprit but I cant justify £800 on a new one just yet. So in a word we have halved our house consumption in a very similar house to you by looking closely at all the appliances and changing the boiler which was well overdue.  The caveat of course is the kids as ours moved out this Summer so no standing in the shower for half an hour and having multi screens and gaming pcs running-- LOL ! Good luck with the reductions