Discuss High gas usage for boiler. in the Gas Engineers Forum area at Plumbers Forums

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71
Hi

Not sure if anyone can give any ideas - but
I’ve got a Worcester Bosch junior 24i system boiler.

For the past 10 years I’ve lived In the house - the average usage of gas has been about 10,000kwh. For the past 2 years my average has been 58000kwh. (Boiler is the only gas appliance in the house!)

It’s Regularly serviced. And from the 3 plumbers I’ve had look at it - they’ve all said - it’s just colder than normal so usage has gone up!

Anyone got any ideas? Is that an increase others are seeing?

SG
 
You are either using it a lot more than before or there is a problem with the meter or you have a gas leak. How long is heating on for is it a combi or do you have a cylinder
 
Hi!

we’ve always had tado installed

It’s a system boiler with unvented cylinder

When we were away, I turned everything off - and gas usage was 0 - which I presume pretty much rules out a leak?

Is there any way to prove the gas meter theory?

Steve
 
Hi!

we’ve always had tado installed

It’s a system boiler with unvented cylinder

When we were away, I turned everything off - and gas usage was 0 - which I presume pretty much rules out a leak?

Is there any way to prove the gas meter theory?

Steve
Other than having it tested, by gas supplier not sure
 
Yes also seen them when they don’t register how is the meter record (for billing) inputted eg do you do it online or does your supplier
 
Hi!

we’ve always had tado installed

It’s a system boiler with unvented cylinder

When we were away, I turned everything off - and gas usage was 0 - which I presume pretty much rules out a leak?

Is there any way to prove the gas meter theory?

Steve
580000kwh/annum = 159kwh/day, doesn't make any sense as this is the winter/summer average.
Can you see the units/decimal places on your meter, depending on what you find, if you can then get your boiler to fire flat out (24kw) for say 5 or even 2 minutes then will soon see if a meter problem.
 
I think your Worcester bosch junior 24i system boiler is not getting the proper gas supply that's why your boiler not working properly. The heating output is 24Kw is ideal for any property with around 15 radiators.

Please share the pics so that I can help you more efficiently. If your boiler comes under the brand warranty then please contact customer care.

The second option will be you can take advice from the professional rooter and plumbing service provider near your area. Because the boiler system needs an engineer to fix it.
 
The boiler is no longer under warranty sadly

We’ve had a number of gas safe engineers to check and service it - so I’d hope they would have confirmed the gas? Would that be part of a service?

What should I take pics of?
 
If the usage is actually ~ 10,000kwh/annum and not 58,000kwh/annum and if a boiler problem then it must be running at around 15% efficiency, (10/58*85%), scarcely believable?, the easiest/obvious first port of call IMO is to monitor the meter readings over a few minutes while running the boiler at its 24kw output.
 
The boiler is no longer under warranty sadly

We’ve had a number of gas safe engineers to check and service it - so I’d hope they would have confirmed the gas? Would that be part of a service?

What should I take pics of?
Can you (also) post a photo of your gas meter.
 
If the usage is actually ~ 10,000kwh/annum and not 58,000kwh/annum and if a boiler problem then it must be running at around 15% efficiency, (10/58*85%), scarcely believable?, the easiest/obvious first port of call IMO is to monitor the meter readings over a few minutes while running the boiler at its 24kw output.
It’s been about 58000/annum for the past 2 years!

I presume I put it in service mode to make sure it’s running full steam? And then monitor the gas meter for the time?

Thank you!
 
If service mode means that it opens all zone valves etc and then fires at 100%, then, yes, if not just turn up the room thermostats and the cylinder stats and ensure all zones calling for heat, then monitor gas usage for exactly two minutes or so, your meter must show decimal point measurement, if not it may have a flashing LED which may be used to monitor like our smart elect meters.

If a combi boiler just open all hot taps & showers.
 
If service mode means that it opens all zone valves etc and then fires at 100%, then, yes, if not just turn up the room thermostats and the cylinder stats and ensure all zones calling for heat, then monitor gas usage for exactly two minutes or so, your meter must show decimal point measurement, if not it may have a flashing LED which may be used to monitor like our smart elect meters.

If a combi boiler just open all hot taps & showers.
So I just did the test - put the boiler in service mode - turned the radiators all on (tado) and then watched the meter for 2 minutes exactly

The reading started at 4559.622 m3 and then went to 4559.672 m3 at the end of the 2 mins.
 
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I think you miss typed ? Either the first or last figure 3rd number in ?
 
That's a consumption of 0.050M3/2min, = 0.050*60/2, 1.5M3/hr, = 1.5*10.8, 16.2kwh = ~ 16.2*85%, 13.8kw boiler output.
That's probably OK as the boiler would not be firing full out to service rads only, So IMO, beyond any reasonable doubt, the meter is reading correctly.
Would suggest monitoring the meter reading over say exactly two full days and see what you consume, to convert..... Kwh = M3X10.8. To annualize it, Kwh = M3X10.8X365/2. (or divide by whatever the monitored period was).Depending on what you get then you must decide your course of action.
 
That's a consumption of 0.050M3/2min, = 0.050*60/2, 1.5M3/hr, = 1.5*10.8, 16.2kwh = ~ 16.2*85%, 13.8kw boiler output.
That's probably OK as the boiler would not be firing full out to service rads only, So IMO, beyond any reasonable doubt, the meter is reading correctly.
Would suggest monitoring the meter reading over say exactly two full days and see what you consume, to convert..... Kwh = M3X10.8. To annualize it, Kwh = M3X10.8X365/2. (or divide by whatever the monitored period was).Depending on what you get then you must decide your course of action.
Thanks for the calculations! I’ll monitor for a few days then report back on the readings.

On the basis the readings are right - it would seem that the boiler must be firing most of the time to use that amount of gas? If so - what are the potential causes that it’s not getting the house to temperature quick enough?

The tado appears to be working - as I’ve stood by the boiler and amended the temperature and the boiler responded accordingly.

Could the pump not be sending the hot water round fast enough? A blockage? Faulty valve somewhere sending the hot water though?
 
Might have got up too early but where's the problem? both are the same, so 4559.672-4559.622 = 0.05M3/2min.
The reading started at 4559.622 m3 and then went to 4559.672 m3 at the end of the 2 mins. Post #16
Apologies - 4559.622 and 4559.672 Post#18
 
Might have got up too early but where's the problem? both are the same, so 4559.672-4559.622 = 0.05M3/2min.
The reading started at 4559.622 m3 and then went to 4559.672 m3 at the end of the 2 mins. Post #16
Apologies - 4559.622 and 4559.672 Post#18
I amended It in the original post to save confusion - seems it did the opposite! Sorry
 
Thanks for the calculations! I’ll monitor for a few days then report back on the readings.

On the basis the readings are right - it would seem that the boiler must be firing most of the time to use that amount of gas? If so - what are the potential causes that it’s not getting the house to temperature quick enough?

The tado appears to be working - as I’ve stood by the boiler and amended the temperature and the boiler responded accordingly.

Could the pump not be sending the hot water round fast enough? A blockage? Faulty valve somewhere sending the hot water though?
Can't say from that meter check reading what your "normal" daily consumption but once your house is up to temp then would expect something like say a boiler output of 3 to 5 kw to maintain that temperature, so maybe monitor it every hour or so as well, and post back.
 
Can't say from that meter check reading what your "normal" daily consumption but once your house is up to temp then would expect something like say a boiler output of 3 to 5 kw to maintain that temperature, so maybe monitor it every hour or so as well, and post back.
After 2 hours, the reading was 4562.288

So its used 2.616m3 in 2 hours
 
The new meter has clocked up 4560 m^3 since 07-Sep-2020. That's a total of ca 10.8 kW hr m^{-3} * 4560 m^3 = 49,250 kW hr over 16 months, which I make 37,000 kW hr / yr. This includes one summer and 1.5 winter seasons so your annual consumpt is more like 30,000 kW hr, roughly half the 58,000 kW hr quoted in post #1. Hence, I think that the 58,000 kW hr must be the total for two years, i.e. 29,000 kW hr.

If I'm right, we're looking for a way to explain an extra 19,000 kW hr per annum, i.e. 52 kW hr / day, or the equivalent of 2 kW continuous loss.

The easiest way to waste this amount of heat without really noticing is to have a hot water leak. This would be quite significant, I make it about 0.62 litre per minute.

Anyway, try comparing the consumption with the cold feed to the hot water cylinder off vs on. Do you have any unbalanced mixer taps/showers? Any applicances fed with hot water? If you look at your water meter, is there an unexplained 0.62 litre per minute of consumption? Did your water consumption jump (by ca 320 m^3 per annum!) at the same time as your gas bill?

(Someone should check my figures and reasoning, I'm pressed for time right now so the above was a bit rushed.)
 
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That seems quite high IMO, its a boiler output of 12kw, would have expected around 50% of this.
Is this whole house heating or just one zone like downstairs, room stat setting also affects usage, I average 4 to 5kwh with downstairs at 20C and upstairs at 16/18C for 16 hours/day, oil firing, 50 year old house.
Have you any bills (personal details redacted) for any summer periods, like the past summer and any summer when the consumption averaged 10,000kwh/annum and ditto for any winter periods?.
Is there very high HW usage like teens continuously showering?.
 
The new meter has clocked up 4560 m^3 since 07-Sep-2020. That's a total of ca 10.8 kW hr m^{-3} * 4560 m^3 = 49,250 kW hr over 16 months, which I make 37,000 kW hr / yr. This includes one summer and 1.5 winter seasons so your annual consumpt is more like 30,000 kW hr, roughly half the 58,000 kW hr quoted in post #1. Hence, I think that the 58,000 kW hr must be the total for two years, i.e. 29,000 kW hr.

If I'm right, we're looking for a way to explain an extra 19,000 kW hr per annum, i.e. 52 kW hr / day, or the equivalent of 2 kW continuous loss.

The easiest way to waste this amount of heat without really noticing is to have a hot water leak. This would be quite significant, I make it about 0.62 litre per minute.

Anyway, try comparing the consumption with the cold feed to the hot water cylinder off vs on. Do you have any unbalanced mixer taps/showers? Any applicances fed with hot water? If you look at your water meter, is there an unexplained 0.62 litre per minute of consumption? Did your water consumption jump (by ca 320 m^3 per annum!) at the same time as your gas bill?

(Someone should check my figures and reasoning, I'm pressed for time right now so the above was a bit rushed.)
Rushed or not, you are right on the ball, annualizing the new meter its ~ 33,231kwh/annum or 91kwh/day, 10,000kwh/annum = 27.4kwh/day, shortfall 64kwh/day. if HW leak then 0.76LPM or 400M3/annum.

So suggest shutting off cold feed to HW cylinder and take another set of hourly readings.
Is the HW cylinder heating controlled by programmer and cylinder stat?.
 
ok, so here is a bill from May/June last year when the heating was off. Water was on constant as it always is (Notice the estimation on the right)


1642074344866.png
Rushed or not, you are right on the ball, annualizing the new meter its ~ 33,231kwh/annum or 91kwh/day, 10,000kwh/annum = 27.4kwh/day, shortfall 64kwh/day. if HW leak then 0.76LPM or 400M3/annum.

So suggest shutting off cold feed to HW cylinder and take another set of hourly readings.
Is the HW cylinder heating controlled by programmer and cylinder stat?.
Yes - There is a cylinder stat - and the hot water Isn’t overly hot so it seems to be controlling it.

FAF1105B-ADB0-4C05-B921-A5F6FA61347C.jpeg


For reference, we have all tank fed showers and baths.
 
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Water usage looks relatively static - although i cant go back any further than 2020

1642077430161.png



And this is an over view of Gas Usage

1642077629064.png


Also, something that may help. Octopus take half hourly readings on the smart meters. You can see here in the report i got that, when the heating turns off at 9pm, no gas is used over night until the heating turns on again at 6am. If there was a water leak, would i not expect to see usage over night as well? it also tells me that my tanks is relatively efficient at keeping the heat in.

1642077959500.png


on the 9th, it seems like the boiler did fire in the middle of the night

1642078153277.png
 
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