Very high Gas consumption?

tellme_why

Hi,
My gas consumption is very high for a 2 people household - 3 bed detached house.
I have a pretty old gas boiler indirect system with new hot water cylinder, gravity system and power shower.
Hot water energy seems very high.. any thoughts?


Total gas/year 23,000kwh
Hot water gas/year 10,700kwh
Hob gas/year 2,800kwh
Heating gas/year 9,500kwh

Boiler consumption 19.7kw, assuming 63% efficiency boiler to water 12.4kw.

Many Thanks

Ebe_Scrooge

It does sound pretty high.  A few thoughts ....

Firstly, you say you have a new hot water cylinder.  I'm guessing it's pretty well insulated, but was the old one insulated?  If not, that can lead to a lot of wasted heat (and may account for historically high usage, which may start to come down a bit as the effect of the new cylinder starts to even out your averages).

What about the house itself?  Double glazing, cavity walls, loft insulation up to scratch, any draughts that need seeing to?

A new boiler will tend to be more efficient than an old one, but only up to a point - and it takes a lot to recoup the initial outlay of a new boiler.

Are you sure your figures are correct (how are you managing to split out the hot water/hob/heating elements of the overall usage?)

If all else fails, might it be worth asking your supplier to check the meter itself?  Those figures do sound very high.

Sorry, not sure I've been much help, but hopefully some ideas to get you started :-)  

ComicGeek

How do you know the breakdown between end uses (heating, hot water & hob)? It's not normal to have gas sub meters on a house, so how have you ended up with those numbers?

Are those estimated, or from the EPC? Is the total gas usage from your actual meter readings or estimated?

FreeBear

Thermostat on the hot water tank ?

I fitted a smart(er) control system for heating & hot water. After tweaking the times & temperatures, my annul gas consumption is around 8500KWh with an old Baxi back boiler. But heating & HW is usually turned off during the summer months. Unless you are tech savvy, I wouldn't recommend my system, so have a look at something like the Drayton Wiser control.

coffeehound

Power showers have a reputation for burning through hot water.  If you could reduce the amount of flow through that, you would surely save some gas.

tellme_why

ComicGeek said:

How do you know the breakdown between end uses (heating, hot water & hob)? It's not normal to have gas sub meters on a house, so how have you ended up with those numbers?

Are those estimated, or from the EPC? Is the total gas usage from your actual meter readings or estimated?

Hi, I measured consumption in July-August which is hot water only (no central heating). I run an experiment with boiler off I measure the consumption of the hob of typical cooking pattern and use a multiplier to get to yearly consumption. I should increase a bit the hot water to account that in winter inlet water is colder.. 

Slinky

Just checked my bill, we're a 2 person household with a similar size 1960s probably not very well insulated house and ours is 16,400 per year with an ancient boiler, gravity system and a pumped shower. In the summer months we're using 386kwh of gas per month (£9 approx) to heat hot water and cook on the hob. We only have the boiler on for about 40-50 minutes twice each a day.

NSG666

2 of us in 3 bed house with combi boiler annual consumption c. 12500kWh.
Do you have the hot water on a timer or constant? If the latter it will waste more. Are all the relevant pipes around the cylinder insulated? Have you got TRVs? Do you leave the heating on all the time? What target temperature?
If it's an old cast iron boiler it might be closer to 50% efficient.

Our annual consumption is c. 12500kWh for 2 living in a 3 bedroom house using a combi boiler.

tellme_why

thanks Sli, mine config is very similar to yours - similar house age and household.. but in july-Aug we consumed 1100 kwh/mth .. boiler is on only during the shower time and cycle 2 more minutes twice at the end of each shower..

tellme_why

NSG666 said:

2 of us in 3 bed house with combi boiler annual consumption c. 12500kWh.
Do you have the hot water on a timer or constant? If the latter it will waste more. Are all the relevant pipes around the cylinder insulated? Have you got TRVs? Do you leave the heating on all the time? What target temperature?
If it's an old cast iron boiler it might be closer to 50% efficient.

Our annual consumption is c. 12500kWh for 2 living in a 3 bedroom house using a combi boiler.

..HW is on Hive schedule from 3 pm to 8pm. Not all pipe are insulated.. the aircupboard is so tight that's difficult to insulate.. also pipes from the ground floor boiler to first floor tank (about 4 m run) are non-insulated copper.. I have TRV all over the place.. boiler is 20yrs potterton profile OEM eff says 75% but must have dropped awhile I suppose..

NSG666

tellme_why said:

NSG666 said:

2 of us in 3 bed house with combi boiler annual consumption c. 12500kWh.
Do you have the hot water on a timer or constant? If the latter it will waste more. Are all the relevant pipes around the cylinder insulated? Have you got TRVs? Do you leave the heating on all the time? What target temperature?
If it's an old cast iron boiler it might be closer to 50% efficient.

Our annual consumption is c. 12500kWh for 2 living in a 3 bedroom house using a combi boiler.

..HW is on Hive schedule from 3 pm to 8pm. Not all pipe are insulated.. the aircupboard is so tight that's difficult to insulate.. also pipes from the ground floor boiler to first floor tank (about 4 m run) are non-insulated copper.. I have TRV all over the place.. boiler is 20yrs potterton profile OEM eff says 75% but must have dropped awhile I suppose..

Cheers they were more meant as variables that could affect your consumption rather for you to actually reply to. Another would be target temp - mine is 18.5deg with 15deg set back whereas I've been in some houses where it's 23deg!!