• Welcome to PlumbersForums.net - The international free plumbing advice forum. Professional plumbers sharing advice with fellow plumbers and DIY alike. Register for free today! - Checkout the Plumbing Advice forum and then our Plumbing Videos area which still needs populating.

Discuss High gas usage for boiler. in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

stevedurban

Messages
68
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
 

Gasmk1

Esteemed
Gas Engineer
Messages
1,952
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
 

stevedurban

Messages
68
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
 

Gasmk1

Esteemed
Gas Engineer
Messages
1,952
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
 

stevedurban

Messages
68
Has anyone ever actually seen a smart gas meter that’s caused higher usage that it actually should be?
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Messages
29,465
Solutions
1
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
 

John.g

Messages
2,497
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.
 

Ronald Jobe

Messages
3
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.
 

stevedurban

Messages
68
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?
 

John.g

Messages
2,497
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.
 

John.g

Messages
2,497
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.
 

stevedurban

Messages
68
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!
 

John.g

Messages
2,497
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.
 

stevedurban

Messages
68
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.
 
Last edited:

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Messages
29,465
Solutions
1
I think you miss typed ? Either the first or last figure 3rd number in ?
 

John.g

Messages
2,497
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.
 

stevedurban

Messages
68
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?
 

John.g

Messages
2,497
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
 

stevedurban

Messages
68
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
 

John.g

Messages
2,497
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.
 

stevedurban

Messages
68
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
 

Chuck

Esteemed
Messages
2,230
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.)
 
Last edited:

John.g

Messages
2,497
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?.
 

John.g

Messages
2,497
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?.
 

stevedurban

Messages
68
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)


You don't have permission to view attachments. Attachments are hidden.

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.

You don't have permission to view attachments. Attachments are hidden.



For reference, we have all tank fed showers and baths.
 

Attachments

    You don't have permission to view attachments. Attachments are hidden.
Last edited:

stevedurban

Messages
68
Water usage looks relatively static - although i cant go back any further than 2020

You don't have permission to view attachments. Attachments are hidden.




And this is an over view of Gas Usage

You don't have permission to view attachments. Attachments are hidden.



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.

You don't have permission to view attachments. Attachments are hidden.



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

You don't have permission to view attachments. Attachments are hidden.
 

Attachments

    You don't have permission to view attachments. Attachments are hidden.
Last edited:

John.g

Messages
2,497
Somethings not adding up now anyway Steve. (maybe good)
You used 1257kwh of gas, apparently for HW heating. This equates to 43.4kwh/day for that 29day billing period. This equals to 36.9kwh/day at a boiler efficiency of 85%.
Assuming cold water at 12C heated to 60C, Litres of hot water = 36.9*860/(60-12), 661Litres.
This would equate to 1133 LPD at 40C.
Your actual water usage for both May and June was 460LPD for each month so ????.

Don't know how they came up with a estimated gas usage of 60550kwh/annum
 

John.g

Messages
2,497
Water usage looks relatively static - although i cant go back any further than 2020

You don't have permission to view attachments. Attachments are hidden.




And this is an over view of Gas Usage

You don't have permission to view attachments. Attachments are hidden.



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.

You don't have permission to view attachments. Attachments are hidden.



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

You don't have permission to view attachments. Attachments are hidden.
You can see from the above that your "present" hourly usage is ~ 0.7M3/30min = 1.4M3/hour=15kwh/hr. or 13kwh/hr useful heat. Are you heating the whole house??.
Maybe turn the cylinder stat down from 60C to its very minimum and use the electric immersion say from 0900 to 1500 hrs tomorrow and monitor gas meter readings.
 

Chuck

Esteemed
Messages
2,230
Water usage looks relatively static - although i cant go back any further than 2020
Er, it was ca 300 litres per day in Feb & Mar 2020 and then jumped up to >550 litres per day and has been slowly declining since then. When do you think that the increased gas consumption started?
 

stevedurban

Messages
68
Somethings not adding up now anyway Steve. (maybe good)
You used 1257kwh of gas, apparently for HW heating. This equates to 43.4kwh/day for that 29day billing period. This equals to 36.9kwh/day at a boiler efficiency of 85%.
Assuming cold water at 12C heated to 60C, Litres of hot water = 36.9*860/(60-12), 661Litres.
This would equate to 1133 LPD at 40C.
Your actual water usage for both May and June was 460LPD for each month so ????.

Don't know how they came up with a estimated gas usage of 60550kwh/annum

thanks for much for the detailed response john.g!

Ill try the Immersion Tomorrow and see if it makes a difference.

Does the immersion have a thermostat on it or will it just keep heating the water?

Er, it was ca 300 litres per day in Feb & Mar 2020 and then jumped up to >550 litres per day and has been slowly declining since then. When do you think that the increased gas consumption started?
is hard to pinpoint because the bills were 6 monthly back then, and now monthly.

Im trying to get hold of the orignal bills but Avro went bust - so i cant get them so easily!

Guys i really appreciate everyones input! thanks for taking the time to help!
 

John.g

Messages
2,497
Yes, The immersion will have its own thermostat, probably set to 60/65C. Make a note of the cylinder stat setting before turning down to minimum, it looks like (and should be) set to 60C.
 

Chuck

Esteemed
Messages
2,230
Assuming cold water at 12C heated to 60C, Litres of hot water = 36.9*860/(60-12), 661Litres.
This would equate to 1133 LPD at 40C.
Your actual water usage for both May and June was 460LPD for each month so ????.
I wonder if the flow temperature being used to heat the DHW tank too low for the tank 'stat setting. E.g. if the flow temperature is 60°C and the tank stat is 65° then the boiler will cycle on and off all day keeping the heating loop that supplies the tank hot and, given there seems to be no insulation visible on the photo perhaps the losses from that would be enough to waste 2 kW.

Is there a programmer that limits the periods that the DWH tank is being heated for? It shouldn't need to be actively heated for more than an hour or two per day.

IME, the flow temperature needs to be a minimum of 5°C above the thermostat-determined setpoint.
 

stevedurban

Messages
68
I wonder if the flow temperature being used to heat the DHW tank too low for the tank 'stat setting. E.g. if the flow temperature is 60°C and the tank stat is 65° then the boiler will cycle on and off all day keeping the heating loop that supplies the tank hot and, given there seems to be no insulation visible on the photo perhaps the losses from that would be enough to waste 2 kW.

Is there a programmer that limits the periods that the DWH tank is being heated for? It shouldn't need to be actively heated for more than an hour or two per day.

Is there any way to confirm that?

The hot water is on permanently 24x7
 

Chuck

Esteemed
Messages
2,230
Is there any way to confirm that?
Measure the DHW temperature from the closest tap with a 0-100°C thermometer. Check the flow temperature the boiler is delivering, which is shown on on its LCD display.

I don't like the way your cylinder stat appears to be away from the side of the cylinder. It should be secured in place with a strap. If the sensor is not in good contact with the pocket you'll have the boiler running continuously and will waste a lot of heat because the circulation loop will be hot 24/7.

The hot water is on permanently 24x7
Why? How much hot water do you use over the course of a day, and when. A programmer gives a good measure of protection from the above issues.
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
Messages
29,465
Solutions
1
Measure the DHW temperature from the closest tap with a 0-100°C thermometer. Check the flow temperature the boiler is delivering, which is shown on on its LCD display.

I don't like the way your cylinder stat appears to be away from the side of the cylinder. It should be secured in place with a strap. If the sensor is not in good contact with the pocket you'll have the boiler running continuously and will waste a lot of heat because the circulation loop will be hot 24/7.


Why? How much hot water do you use over the course of a day, and when. A programmer gives a good measure of protection from the above issues.

Unvented so pocket stat with sensing bulb set to 50dc
 

Reply to High gas usage for boiler. in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

Similar threads

J
Thanks I will get the guy who’s dealing with it to check this out.
Replies
12
Views
311
jennygardner2
J
elvis80
Replies
7
Views
684
elvis80
elvis80
H
If its a conversion, depending how well it was done, sometimes part of another property can be fed by your supply. Have you taken a daily reading...
Replies
5
Views
739
W
S
Thames Water have ruled that out. :-(
Replies
31
Views
349
SandraKJ
S
T
I’ve a 400 square metre 5-story house, with an unvented heating system and the hot water on a return loop, as the boiler is in a block at the far...
Replies
0
Views
231
Tony_P
T

Newest Threads (Please Reply)

Search Forum

Top