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

StillNotRich

Gerry1 said:

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.

Sorry, i probably wasn't clear. Running at full blast for a minute (I did it a few times), the boiler used 0.06 M3 of gas, so 3.6 M3 per hour, that calculates to 39.88kWh using the formula given on my bill (correction factor, calorific value and conversion factor).

This seems correct for a 40kwh boiler, i.e. there is nothing wrong with the meter (unfortunately).

Cheers

rp1974

StillNotRich said:

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.

Devils advocate here,just how often is this boiler breaking down?,and don't these items have timers/controls thus avoiding the need to remember to turn them on/off?.

StillNotRich

Robin9 said:

@StillNotRich    12,000 KWh yes in a modern semi with a 2.2 family with parents out at work

What's your electric consumption ?

My electricity is also high - about 6,000kwh per year. I suspect that could be correct (we are not good at turning things off standby). I also suspect there might be a different issue - we actually have 3 phase electricity (the previous owner was an electrician), its not impossible that there is some confusion with the supply/meter which I've asked the supplier to look at. 

I didn't mention this in my original post to avoid confusing the matter.

Cheers

StillNotRich

rp1974 said:

StillNotRich said:

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.

Devils advocate here,just how often is this boiler breaking down?,and don't these items have timers/controls thus avoiding the need to remember to turn them on/off?.

That is a good point, we have always had an issue with the system losing pressure, every few months in winter we had to repressurize the expansion tank and re-set the boiler. This was finally fixed a few months ago when the plumber ran some anti leak additive through the system (not sure why no-one had ever suggest that!). For that reason we often didn't have hot water unless we used the "spare" tank...

It might be that that loss of pressure was causing the boiler to be inefficient? 

Cheers

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?

Yes, this is definitely something i need to investigate.

Cheers

mrsmsebastian

reading all your comments regarding your annual consumptions made me realise that we are doing well in terms of our usage. I have always been strict with my kids regarding their electric and gas usage as I thought we are using and paying too much. I think I will be a bit more lenient from now on.

Our annual usage is 2,286 kwh for electricity and 7,710 kwh for gas. Our boiler is worcester greenstar 25i combi boiler and our property is 3 bed semi-detached bungalow with 2 adults and 2 kids at home and a Uni student son staying on school holidays.

Gerry1

mrsmsebastian said:

reading all your comments regarding your annual consumptions made me realise that we are doing well in terms of our usage. I have always been strict with my kids regarding their electric and gas usage as I thought we are using and paying too much. I think I will be a bit more lenient from now on.

Our annual usage is 2,286 kwh for electricity and 7,710 kwh for gas. Our boiler is worcester greenstar 25i combi boiler and our property is 3 bed semi-detached bungalow with 2 adults and 2 kids at home and a Uni student son staying on school holidays.

@mrsmsebastian You're not doing well, you're doing incredibly well with all those people, especially as it's a bungalow.

However, for peace of mind it might be worth double checking to avoid an unpleasant surprise if it turns out that something isn't right.

Make sure you don't have an imperial meter (100s of ft3) that's mistakenly being billed as a metric meter (m3).  If so, the real kWh usage will be 2.83 times the figures shown on the bills.  (In other words, if the meter is imperial and you see 2.83 in the calculation then you're OK.)

Make sure that neither your meter readings nor your annual usage have been estimated.

FreeBear

Gerry1 said: (In other words, if the meter is imperial and you see 2.83 in the calculation then you're OK.)

And if you see the 2.83 figure, and your meter is metric, jump on the supplier and demand a refund - You will have been overpaying for the gas.

Gerry1

StillNotRich said:

Gerry1 said:

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.

Running at full blast for a minute (I did it a few times), the boiler used 0.06 M3 of gas, so 3.6 M3 per hour, that calculates to 39.88kWh using the formula given on my bill (correction factor, calorific value and conversion factor).

This seems correct for a 40kwh boiler, i.e. there is nothing wrong with the meter (unfortunately).

Nope.

Running at full blast for a minute (I did it a few times), the boiler used 0.06 M3 of gas, so 3.6 M3 per hour.

That calculates to 39.88kWh per hour,

which is 39.88kWh/h,

which is 39.88kW,

which seems the correct instantaneous power for a 40kW  h  boiler, i.e. there is nothing wrong with the meter (unfortunately).

FTFY ! 

Magnitio

StillNotRich said:

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.

A good quality hot water cylinder will lose heat at a rate of about 50W. Older, less efficient cylinders can be far worse. So, for two seperate cylinders, you could be using 1000kWh per annum just to keep the water hot even if none is used.

If the pipes between your boiler and the cylinders are long and uninsulated, or your cylinder thermostats are set too high, you will also be wasting a lot of energy, though during the winter, this may help with keeping the house warm.