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stevedurban

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64
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

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2,486
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

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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

Messages
64
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:
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Boiler is on 6

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We don’t generally touch them all year round.
 

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stevedurban

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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


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

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

stevedurban

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64
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?
 

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John.g

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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

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64
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

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2,486
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

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64
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!)
 

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John.g

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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

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64
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

Messages
64
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

Messages
2,486
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

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

stevedurban

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64
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?

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John.g

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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.
 
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stevedurban

Messages
64
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!)

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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.
 

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ShaunCorbs

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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
 

John.g

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2,486
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?.
I thought you meant the central heating was on for 3hrs/day.
148kwh/day, if so, seems a bit on the high side, 148/17.5= 8.46kwh/hr, bit on the high side but not outrageous either.
 

stevedurban

Messages
64
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.
Just on the last point - I spent a fair amount of time previously running back and forth watching the valves and boiler to check it didn’t have the flame symbol lit on the front whilst the valves were closed and it didn’t seem to! The boiler is still pumping (which i believe is correct) but no flame.
 

John.g

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2,486
What do you mean by the boiler pumping?.
I think Tado works something like Evohome where the rads "TRVs" are actuated/controlled by it, and depending on actuator positions fires the boiler on/off so wonder what does the the CH mot.valve do?.
 

stevedurban

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64
What do you mean by the boiler pumping?.
I think Tado works something like Evohome where the rads "TRVs" are actuated/controlled by it, and depending on actuator positions fires the boiler on/off so wonder what does the the CH mot.valve do?.
I meant I could hear the pump running on the boiler - but the “[email protected] was off!

Here was the reading 2 hours ago
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Here was the reading after 2 hours

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stevedurban

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Revta
I meant I could hear the pump running on the boiler - but the “[email protected] was off!

Here was the reading 2 hours ago
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Here was the reading after 2 hours

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Re tado - yes - there are TRV’s on all radiators - and they speak with the thermostats In the rooms. The thermostats tell the TRV’s to open and the boiler to kick in. We have it that only the downstairs thermostat has the ability to call for heat - the upstairs only gets to temperature when they downstairs is calling.
 

John.g

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2,486
Your meter readings = 21.9kwh for 2 hours (boiler on, I hope)
Interesting re Tado, I can understand the upstairs M.valve just calling for heat when its roomstat calls, but if its the same so for the DHW M.valve, then in the summer with no CH demand how is this catered for, unless there a separate relay fed from the HW M.valve or somewhere else that calls in the boiler?.

Re boiler running pump, in a normal S plan this will run continuously with a call for the boiler to run, the boiler burner will cut in/out if its output is > the heating demand but pump will continue to run and will only stop after no call from CH or DHW (or boiler programmed off). So why is your pump running all the time, is the boiler on all the time and if no demand will fire up/down on its own boiler stat?.
 

stevedurban

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Your meter readings = 21.9kwh for 2 hours (boiler on, I hope)
Interesting re Tado, I can understand the upstairs M.valve just calling for heat when its roomstat calls, but if its the same so for the DHW M.valve, then in the summer with no CH demand how is this catered for, unless there a separate relay fed from the HW M.valve or somewhere else that calls in the boiler?.

Re boiler running pump, in a normal S plan this will run continuously with a call for the boiler to run, the boiler burner will cut in/out if its output is > the heating demand but pump will continue to run and will only stop after no call from CH or DHW (or boiler programmed off). So why is your pump running all the time, is the boiler on all the time and if no demand will fire up/down on its own boiler stat?.
So we have a standard 2 splan - one M.valve for heating (which feeds all the radiators in the house) and one one for water.

Tado controls both independently. When the downstairs thermostat calls for heat - it tells the tado controller to open the DHW valve - and boiler starts etc etc. the other thermostats around the house just tell the radiators in their “zone” to open and close as needed. If the downstairs is calling for heat at that moment - the radiators will get hotter. If downstairs isn’t calling for heat - they won’t get hotter. (That’s our choice - and was recommended by tado to do this)

When I was mentioning about hearing the pump - I was referring to the overrun. It sounds like the pump keeps pumping for about 5 mins from the time the last valve closes - and then the boiler is quiet. I presume this is by design.

When either valve is open - you hear the boiler in full force.

You mentioned about the boiler pump running constantly with a call to the boiler to run - and not burning if the output is > the heating demand? But surely if the heating demand isn’t met - the boiler should be burning? And if the heating demand is met (room stat hits temperature) the value would close - and the boiler would stop anyway? So what scenario would the valve be open - but not calling for heat?
 

stevedurban

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64
So we have a standard 2 splan - one M.valve for heating (which feeds all the radiators in the house) and one one for water.

Tado controls both independently. When the downstairs thermostat calls for heat - it tells the tado controller to open the DHW valve - and boiler starts etc etc. the other thermostats around the house just tell the radiators in their “zone” to open and close as needed. If the downstairs is calling for heat at that moment - the radiators will get hotter. If downstairs isn’t calling for heat - they won’t get hotter. (That’s our choice - and was recommended by tado to do this)

When I was mentioning about hearing the pump - I was referring to the overrun. It sounds like the pump keeps pumping for about 5 mins from the time the last valve closes - and then the boiler is quiet. I presume this is by design.

When either valve is open - you hear the boiler in full force.

You mentioned about the boiler pump running constantly with a call to the boiler to run - and not burning if the output is > the heating demand? But surely if the heating demand isn’t met - the boiler should be burning? And if the heating demand is met (room stat hits temperature) the value would close - and the boiler would stop anyway? So what scenario would the valve be open - but not calling for heat?
P.s - thank you so much for your patience, advice and understanding! I really appreciate it!
 

ShaunCorbs

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The meter reads nothing when not on / out

The meter is reporting the correct kWh over time heating / hot water been on around 8 hours total at 24kw

How long has the tado kit been installed?
 

John.g

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2,486
That's correct, all boilers have a minimum output, depending on boiler manufacturer, boiler output etc, it will be ~ say 3 to 6 kw so if the heating demand is below this then the boiler temperature will rise and the burner will cut out when this temperature reaches its setpoint+3C (normally) and the burner will cut back in when the boiler temp is its setpoint-3C plus the boilers anticycling time which may be ~ 3 mins, the pump will continue to run because the demand for heat has not gone away.

"When the downstairs thermostat calls for heat - it tells the tado controller to open the DHW valve" do you mean the CH m.valve? The DHW valve is also controlled by the cyl stat.
 

stevedurban

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64
The meter reads nothing when not on / out

The meter is reporting the correct kWh over time

How long has the tado kit been installed?
Correct - the question is is the boiler using more gas than it should?

Tado been installed for 10 years. I added digital tado room stats about a year ago in the hope that it would help… alas it didn’t!
 

ShaunCorbs

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Doesn’t look like so you’ve had this problem for a while ?

“I added digital tado room stats about a year ago in the hope that it would help… alas it didn’t!”
 

stevedurban

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64
That's correct, all boilers have a minimum output, depending on boiler manufacturer, boiler output etc, it will be ~ say 3 to 6 kw so if the heating demand is below this then the boiler temperature will rise and the burner will cut out when this temperature reaches its setpoint+3C (normally) and the burner will cut back in when the boiler temp is its setpoint-3C plus the boilers anticycling time which may be ~ 3 mins, the pump will continue to run because the demand for heat has not gone away.

"When the downstairs thermostat calls for heat - it tells the tado controller to open the DHW valve" do you mean the CH m.valve? The DHW valve is also controlled by the cyl stat.
Apologies yes - when the CH valve will open when downstairs calls for heat!
 

John.g

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2,486
So, what tells the boiler to start when there is a call for DHW in high summer or anytime for that matter when all TRVs are shut?.
 

stevedurban

Messages
64
Doesn’t look like so you’ve had this problem for a while ?

“I added digital tado room stats about a year ago in the hope that it would help… alas it didn’t!”
Yes - I’ve had it for over a year - maybe 2. I’ve gone through cycles of trying to find a solution. Each plumber that came - serviced it and said - “it cold - so you use more heat! - and that was it! They didn’t really check anything - never checked the gas meter for usage per min etc… I just couldn’t find anyone with any drive to just confirm their theory! If it is just I’m using more gas - then so be it!

I just can’t understand why for 8years or so of living in the house - my estimated average gas usage on every bill has been 6-10,000 and a bill of around £120 a month (averaged over the year). I’m now heading to an average of 60,000 according to their estimations (185kwh today!)
 

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