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

michaels

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.

macman

Gas: the giveaway here is that the OP used 600kWh of gas in a month when they were away for 22 days, and  turned the heating off in their absence. Other than gas CH and DHW, their only other gas appliance is the hob.
That equates to using 75kWh a day just for hot water and the hob, or 27,375kWh pa-without any heating. But the OP is only using 32,000kWh with heating.
Barring a gas leak downstream of the meter, which can be ruled out by a quick check, the only rational explanation is a greedy pilot light and an extremely old and inefficient non-condensing boiler.

theoretica

I would look at moving the thermostat controller out of the hall.  The hall is not - presumably - the room you care about the temperature of.  If you do decide to get a new boiler, making sure any controller is battery powered so you can pick it up and put it where you want it makes sense.  TRVs as a minimum on all radiators - they do not talk to the thermostat, just shut that radiator off when they are warm.  But maybe more advanced controllers would be worth thinking about which could be set to a timer too.  Or getting in the habit of adjusting the valves manually - turning the bedroom ones down as you get up.

I still think 600kWh of gas when you were mostly away is a problem - some of that will be pilot light, but much of it will be an indication of heat loss from the hot water system - pure waste.  Well not quite totally as in winter it would help heat the house, but uncontrolled spending and not where you wanted to heat.

FreeBear

Coffeekup said: Stop! Turning the water tank down to 45*C is a legionella risk at that temp. Put it it back to 60-65*C, I think @freebear was talking about a combi boiler water setting.

Legionella is a very, very small risk in the UK with just 200-250 cases reported annually. If you have an open tank of still water (e.g. a header tank), the risk increases slightly. Should there be any concerns about Legionella and you have a hot water tank with a header tank (as opposed to an unvented tank or a combi boiler), maintaining a water temperature of 50-55°C for two hours or so is sufficient to kill the bacteria (see image below). At 60-65°C, bacteria is killed within minutes, but you are then at greater risk of scalding from the hot water unless you have thermostatic mixers on all the taps - An important fixture with small children or vulnerable/elderly adults around.

macman

It's assumed that the OP turned off both the CH and DHW during their absence in July, so how do you conclude that the main cause is heat loss from the hot water system?

Krakkkers

I use my immersion heater and the thermostat is set to max at 85 degrees !!!

ManMadeWays

Some things we did :

In a 6 bed extended 1930s semi with 5 adults our Gas was 28,000 Kw/h. I've reduced that to Circa 18,000 Kw/h using Drayton Wiser Smart TRVs with each room having it's own temperature/time profile, I've reduced the CH flow temperature and tried to balance the rads to achieve a 20 degree loss from flow to return, also reduced the DHW temperature. (Vaillant Ecotec 937 Combi ). I've improved underfloor insulation in an original ground floor room that allowed a gale to blow in, also a chimney sheep , stopping warm air going up chimney.

Under the stairs cupboard has a hole allowing cold air in so that's next , as well as a poorly insulated ground floor bathroom.

Electicity was around 7,300 Kw/h, this is tougher to crack, especially with 3 WFH full time, nevertheless sacrificed one pond pump and put another pump/UV on a 12 hour timer. I've put Wifi cards in 4 PCs and switched off 2 LAN switches, moved a router so I can switch off a couple of WIfi Access Points.

I have now got several Tapo automated switches (also power monitors) they reveal Gaming PC/monitor setups using up to 350Watts/Hour, so they are all set to sleep after 10 minutes as I often found them left on for hours. Switched off a NAS drive as we didnt use it.

So likely to get down to 6,300 Kw/h so still expensive.

Need to check the freezer next, it's about 14 years old,get an air fryer/slow cooker combo to save on oven costs.

Lights are all LED so no issue there but I go round switching rooms off out of habit

phillw

ManMadeWays said:

Lights are all LED so no issue there but I go round switching rooms off out of habit

LED are more efficient, but they still use a reasonable amount of power.

Especially if you have 4 or 8 of them in a room.

theoretica

macman said:

It's assumed that the OP turned off both the CH and DHW during their absence in July, so how do you conclude that the main cause is heat loss from the hot water system?

It isn't assumed so by me - as not turning hot water off seems to me the simplest explanation for such a high gas use that month.  OP can you clarify?  Can you get smart meter data for what the house was using when you weren't even there to benefit?

michaels

theoretica said:

macman said:

It's assumed that the OP turned off both the CH and DHW during their absence in July, so how do you conclude that the main cause is heat loss from the hot water system?

It isn't assumed so by me - as not turning hot water off seems to me the simplest explanation for such a high gas use that month.  OP can you clarify?  Can you get smart meter data for what the house was using when you weren't even there to benefit?

Heat loss from a hot hot water tank should be of order 1-2.5kwh per day.  OP vampire loss (based on difference between June and July) seems to be about 440/30 = 14.5kwh per day.