High gas usage for boiler.

[stevedurban]

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

 

[John.g]

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]

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

View attachment 72749



And this is an over view of Gas Usage

View attachment 72751


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.

View attachment 72753


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

View attachment 72755

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]

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]

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]

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]

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]

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

 

[John.g]

There is a motorized valve+cylinder stat but apparently HW is on "all day".

 

[Chuck]

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]

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

 

[stevedurban]

i was told (rightly or wrongly) when it as fitted that they are so super efficient, that it can be left on all the time because they will only really heat when you use the hot water, because the thermal loss is so negligable.

However, your point is very valid that if there are issues, it could be heating all day!

The house would have 2 baths and 1 shower in an evening normally - so from a quick google, thats maybe 90L? tank is 210 - so if we just have the water on tomorrow for 2 hours at 12pm tomorrow, that should cover the day?

 

[John.g]

What is the cylinder stat set to now and what is the boiler temperature (set point) now, does this setting be changed in summer/winter?.

Two baths at 88 Litre/bath? and 45C is equivalent to 123 litrs of cyl HW at 60C so ~ 77 litres at 60C remaining = 128 litres at a showering temp of 40C = 10 min shower at 13LPM.
12kwh required to heat tank from cold so 2 hours should be fine as cylinder stat will cut out boiler anyway??.

 

[Chuck]

Another couple of faults that need to be ruled out:

1. The CH zone valve were letting by when it should be closed. The CH radiator system would then act as a bypass for the DHW cylinder and waste a lot of heat in the process.

2. An incorrectly set automatic bypass valve (ABV) opening when the cylinder is heating.

P.S. Sorry if these ideas have already been discussed; I'm not able to read most of the posts at the moment because everything is covered in adverts.

 

[stevedurban]

What is the cylinder stat set to now and what is the boiler temperature (set point) now, does this setting be changed in summer/winter?.

Two baths at 88 Litre/bath? and 45C is equivalent to 123 litrs of cyl HW at 60C so ~ 77 litres at 60C remaining = 128 litres at a showering temp of 40C = 10 min shower at 13LPM.
12kwh required to heat tank from cold so 2 hours should be fine as cylinder stat will cut out boiler anyway??.

cylinder stat:


Boiler is on 6



We don’t generally touch them all year round.

 

[stevedurban]

Another couple of faults that need to be ruled out:

1. The CH zone valve were letting by when it should be closed. The CH radiator system would then act as a bypass for the DHW cylinder and waste a lot of heat in the process.

2. An incorrectly set automatic bypass valve (ABV) opening when the cylinder is heating.

P.S. Sorry if these ideas have already been discussed; I'm not able to read most of the posts at the moment because everything is covered in adverts.

1) any way to prove this option?
2) here is the external abv




Is there an internal one in the boiler that may need checking.

 

[ShaunCorbs]

Turn the cylinder stat down boiler should go off if it’s heating the hot water

 

[stevedurban]

I’m pretty sure the house is calling for heat almost all day - and just no longer able to get up to temperature. Tado shows in the heat graphs as follows. The darker area shows when the boiler is firing constantly. The medium grey means it’s coming on and off a few times an hour apparently - and the light colour is off (this is heating only!)
The house is relatively well insulated, loft conversion to regs 5 years ago. Cavity wall insulation installed 10 years ago. Double glazed throughout.

When I discussed the issue with tado - they said looking at the graph for how the temperature drops from when the heating is off over night, the house only looses about 3 degrees over night - which he said was relatively good!

So could Chucks opinion that maybe something like a bypass not working properly - causing the water to go round and round instead of to the radiators be an issue?or something along those lines? Pump not pushing hard enough?

 

[John.g]

Can you see the actual boiler temperature from the boiler display to confirm that the high setting 0f 6+ is actually reflected in the boiler temperature.
Also, as suggested above, turn the cylinder stat up if the motorized valve is shut and ensure it opens and turn it down if the motorized valve is open and ensure it shuts.
If the boiler temperature is as high as it might be, 75C+, and if the DHW temperature doesn't feel scalding then a fair indication that its temperature is being controlled to its setpoint of 50C. (should really be 60C, for legionella protection).

 

[stevedurban]

Can you see the actual boiler temperature from the boiler display to confirm that the high setting 0f 6+ is actually reflected in the boiler temperature.
Also, as suggested above, turn the cylinder stat up if the motorized valve is shut and ensure it opens and turn it down if the motorized valve is open and ensure it shuts.
If the boiler temperature is as high as it might be, 75C+, and if the DHW temperature doesn't feel scalding then a fair indication that its temperature is being controlled to its setpoint of 50C. (should really be 60C, for legionella protection).

I tested the boiler stat - the valve was closed - I turned the boiler stat up and the valve opened. As soon as I turned it back down - the valve closed again.

Unfortunately the boiler doesn’t have a display - only the dial.

 

[John.g]

Ok then, the flow pipe from the boiler should be absolutely scalding and you should only be able to touch it for a very short time.

 

[stevedurban]

Ok then, the flow pipe from the boiler should be absolutely scalding and you should only be able to touch it for a very short time.

Yes - scalding hot

Not sure if it’s right - but both sides of the ABV are also scalding.

(Hot pipes in red!)

 

[John.g]

They certainly shouldn,t especially when the index is set to 0.5? (5M), there may be a bit of crap under the seat, with the boiler running slowly, adjust (anti clockwise) the setting knob, you should hear some noise if the ABV starts opening at ~ 0.3/0.4, then reset it back to 0.5.
If it is in fact passing badly, the boiler return should also be very hot.

 

[stevedurban]

They certainly shouldn,t especially when the index is set to 0.5? (5M), there may be a bit of crap under the seat, with the boiler running slowly, adjust (anti clockwise) the setting knob, you should hear some noise if the ABV starts opening at ~ 0.3/0.4, then reset it back to 0.5.
If it is in fact passing badly, the boiler return should also be very hot.

They certainly shouldn,t especially when the index is set to 0.5? (5M), there may be a bit of crap under the seat, with the boiler running slowly, adjust (anti clockwise) the setting knob, you should hear some noise if the ABV starts opening at ~ 0.3/0.4, then reset it back to 0.5.
If it is in fact passing badly, the boiler return should also be very hot.

So I just tested as described. The tank was calling for heat. I adjusted the abv to around 0.3 and no different sounds. When the tank stopped calling - I could hear a new sound which was obviously water going through the abv - I’ve never heard this noise before.

I thought the idea of the abv was that when the boiler ran and then stopped calling for heat - and the valves closed - the water should pass through the abv to allow the pump to slow without excess pressure on the pump? If the abv was doing it’s job (and there isn’t another one in the boiler) then I should have been hearing that sound every time both valves just closed?

 

[stevedurban]

Can you see the actual boiler temperature from the boiler display to confirm that the high setting 0f 6+ is actually reflected in the boiler temperature.
Also, as suggested above, turn the cylinder stat up if the motorized valve is shut and ensure it opens and turn it down if the motorized valve is open and ensure it shuts.
If the boiler temperature is as high as it might be, 75C+, and if the DHW temperature doesn't feel scalding then a fair indication that its temperature is being controlled to its setpoint of 50C. (should really be 60C, for legionella protection).

Just to confirm - I set the tank stat to 60 - and after a while tested the water temp of the nearest tap - and it was 59.9

 

[John.g]

It was probably never set up properly, you are possibly the first person to touch it, if the no flow pump head is less than 5M (0.5bar) then the ABV will never open, so you can adjust it around that setting (of 0.3) so that it only opens when both mot.valves shut and the pump is on overrun.

Just to confirm - I set the tank stat to 60 - and after a while tested the water temp of the nearest tap - and it was 59.9

Well, back to square one so re high gas consumption as the cyl temp is being controlled and even if left enabled all day shouldn't account for that excess gas usage which was mad during the summer , see post #31, even 12kw current usage seems quite high once house up to temp?.
You said you might try running on the immersion for a day or two to rule out HW usage?.
Can you also not programme the HW cylinder to be heated for a few hours in the morning?, can't remember if you said that it has its own programmed zone.

If the ABV is passing then that will consume a fair few M3 of gas via unlagged copper pipes, the easiest way to check it is when/if the system is cold in the morning and just after the boiler fires up, keep your hand on the vertical ABC (downstream) pipe which should remain cold for a long period, if not leaking it could still possibly feel very hot due to conduction.

 

[ShaunCorbs]

Abv is shot by the sounds of it as it shouldn’t be passing when the system is on / running

 

[stevedurban]

It was probably never set up properly, you are possibly the first person to touch it, if the no flow pump head is less than 5M (0.5bar) then the ABV will never open, so you can adjust it around that setting (of 0.3) so that it only opens when both mot.valves shut and the pump is on overrun.


Well, back to square one so re high gas consumption as the cyl temp is being controlled and even if left enabled all day shouldn't account for that excess gas usage which was mad during the summer , see post #31, even 12kw current usage seems quite high once house up to temp?.
You said you might try running on the immersion for a day or two to rule out HW usage?.
Can you also not programme the HW cylinder to be heated for a few hours in the morning?, can't remember if you said that it has its own programmed zone.

If the ABV is passing then that will consume a fair few M3 of gas via unlagged copper pipes, the easiest way to check it is when/if the system is cold in the morning and just after the boiler fires up, keep your hand on the vertical ABC (downstream) pipe which should remain cold for a long period, if not leaking it could still possibly feel very hot due to conduction.

So for the past 3 days I’ve set tado to only turn the heating on for 2 hours a day (11-1) - and the usage hasn’t changed. I also checked when it was off that turning the tank stat up didn’t call for heat and open the dhw valve - and it didn’t - so we know that’s off.

Today upto 6pm so far I’ve used 148kwh!! It’s crazy!!! There has to be something wrong somewhere!! Just not sure where to turn!!

On the abv pipes - it’s only a short way to the return pipe coming out the tank - so that pipe always seems to be hot (rightly or wrongly?)

If the HW is off - should any heat be coming out that pipe from the tank? Or is the fact it’s hot either a fault or the ABV working?

 

[John.g]

So you have used 148kwh in, 3X2, 6 hours in total which is almost 25kwh (per hour), is that correct? Is it a 24kw boiler, can't remember?.
Can you set up a camera to monitor the Gas Meter to monitor those 2 hours each day or have you noted the readings at the end of each day period and start of next days period to ensure no usage in the intervening time?.

If the ABV pipework has been installed then the supply to it should be teed off before any motorized valve, can't see it properly but if its taken off before the (or any) HW M.valve then correctly installed, so as long as the boiler is firing the ABV is "live" and can leak, but boiler will hardly be firing (we hope) with both M.valves shut?.

Just thinking, the boiler is/should only be started when either of the M.valves open by means of (end) switches in their actuators.

 

[stevedurban]

So you have used 148kwh in, 3X2, 6 hours in total which is almost 25kwh (per hour), is that correct? Is it a 24kw boiler, can't remember?.
Can you set up a camera to monitor the Gas Meter to monitor those 2 hours each day or have you noted the readings at the end of each day period and start of next days period to ensure no usage in the intervening time?.

If the ABV pipework has been installed then the supply to it should be teed off before any motorized valve, can't see it properly but if its taken off before the (or any) HW M.valve then correctly installed, so as long as the boiler is firing the ABV is "live" and can leak, but boiler will hardly be firing (we hope) with both M.valves shut?.

No sure what you mean about 3x2? Heating comes on at 6am - and goes off at 9pm. Water is heated only 11-2

I will be able to see half hourly reports from octopus energy tomorrow as the smart meter uploads each night.

I can see yesterdays report already. It seems to be about .7m3/hour From 6.30am-12pm. It doesn’t seem to peak between 11-2 (the water was on that setting already yesterday!)

As for the ABV - It’s piped before the valves - so that seems right! It seems to overrun for about 5 mins when the valves shut.

 

[ShaunCorbs]

Turn heating and hot water heating off and see what your software registers

Boiler shouldn’t fire at all when everything is set to off