Huge Gas Usage of 32,000 kWh per year - Help !

welshblob

michaels said:

Magnitio said:

tiya1990

Hi,

Do you notice whether the boiler runs continuously during the period that you have set the hot water to be on?

I noticed that the setting on your boiler is very low. Was it set like that by the person who serviced your boiler? This could result in the output temperature from your boiler being lower than the thermostat setting on the hot water tank, so the boiler would run continuously based on the timer. Another possibility is that the three-way valve is malfunctioning and not sending all of the hot water from the boiler through the coil in the hot water tank; again this would result in the boiler running for much longer.

The usage does look more like the heating was running, the tank is insulated modern style, should only be losing 1-2kwh per day.  Only thing is, surely the OP would notice the rads getting hot?!

Would the boiler just continue to run at a lower temp if the boiler temp was lower than the tank cut off temp?  Where would all the energy go?  Perhaps it would cycle on and off continuously but then I can't see the air temp would make such a huge difference.

I noticed my rads getting hot when my three way valve got stuck. However this is an unvented system and mine is a vented and looking at the pics I can see it only has a two way valve and the body looks quite shiny and new so wonder if that has been replaced? Quick way to tell if the valve is working is to turn DHW on only  and see if both pipes either side of the valve are hot, the bottom one shouldn't be. I assume that this system can only provide CH and DHW or just DHW as I can't see another valve before it goes from the tank unless it's obscured by the red expansion vessel? Not sure what would have caused the corrosion on the Flexi from the top expansion vessel. 
Also the boiler is set to 2 which is quite low but the tank thermostat is on 45 which is also low so it shouldn't be on a constantly firing. Either the system is losing that heat, say to the rads or the boiler is not being controlled by the tank thermostat and is constantly on ....although I think the boiler also senses the temp on the return and would turn itself off if too high?

Mstty

bagand96 said:

tiya1990 said:

Hot Water - our water was being heated twice a day between 5am - 8am and 5pm - 10pm even when we were away according to OH .

I would definitely try and reduce that.  You know your family's routines best, but it's unlikely you need to have the water on for 8 hours a day.  As another poster said before, your water is thermostatically controlled so the boiler won't be running the whole 8 hours, but it could easily be cycling on and off to warm the tank up, when in reality the water would be warm enough anyway.  Your cylinder looked fairly modern so should be fairly well insulated.  Perhaps try cutting an hour off the morning and 2 hours off the evening and see how you go.  If you run out of hot water then fine, adjust it back.  If you don't, consider reducing further.  

As an example, I took your Gas use from when you were away and compared it to the temperature recorded in Birmingham on those days.

Date	kWh	Temp
2nd July	23.28	16
3rd July	23.99	18
4th July	22.68	19
5th July	23.08	20
6th July	19.94	22
7th July	19.16	22
8th July	15.64	26
9th July	14.32	24
10th July	12.66	28
11th July	9.4	29
12th July	8.74	25
13th July	11.39	23
14th July	13.41	21
15th July	16.11	23
16th July	13.92	26
17th July	10.25	30
18th July	8.58	36
19th July	6.79	37
20th July	7.5	26
21st July	15.5	20
22nd July	17.25	22
23rd July	18.53	22
24th July	17.7	24

It's obvious that on the hottest days (and there were some scorchers!) less gas was used.  That's because the water cylinder would be losing less heat, because the house was warmer.  But a lot of Gas kWh were wasted heating a water cylinder that no-one was using!  Lowest day was 6.79 kWh, which may have just been the pilot light sat there quietly doing it's thing - although even on that day I bet some energy was used to heat water so the pilot light is probably under 4/5 kWh a day.

I agree with other posters, a new condensing boiler is probably the way to go here, but I still reckon reducing the time you have your water on will also help a bit and could be done today for free!

Sorry if I have read this wrong but it is long touted on this forum that a reheating cylinder will lose only 1-2.5kWh a day.

I haven't read the whole thread but is this just the OP heating their hot water whilst away and the loss of heat costing this much gas?

QrizB

Mstty said:

agree with other posters, a new condensing boiler is probably the way to go here, but I still reckon reducing the time you have your water on will also help a bit and could be done today for free!

Sorry if I have read this wrong but it is long touted on this forum that a reheating cylinder will lose only 1-2.5kWh a day.

I haven't read the whole thread but is this just the OP heating their hot water whilst away and the loss of heat costing this much gas?

It's still a mystery where all this gas is going.

It's unlikely that it's being spent on hot water, unless there's a hot water tap that keeps trickling away.

W e were wondering if their CH control valve was stuck open but that would mean the radiators getting hot.

It looks like their boiler, while old, doesn't have a permanent pilot light.

I don't think the OP has tested their gas meter yet, so it could possibly be a faulty meter? That's quite a long shot.

DeeQS

I moved into a new house in Jan and noticed that when our hot water was on, the boiler would run permanently. 

Turns out we had a fault thermostat on the cylinder. It caused the boiler to just run at a low kWh usage the whole time.

michaels

QrizB said:

Mstty said:

agree with other posters, a new condensing boiler is probably the way to go here, but I still reckon reducing the time you have your water on will also help a bit and could be done today for free!

Sorry if I have read this wrong but it is long touted on this forum that a reheating cylinder will lose only 1-2.5kWh a day.

I haven't read the whole thread but is this just the OP heating their hot water whilst away and the loss of heat costing this much gas?

It's still a mystery where all this gas is going.

It's unlikely that it's being spent on hot water, unless there's a hot water tap that keeps trickling away.

W e were wondering if their CH control valve was stuck open but that would mean the radiators getting hot.

It looks like their boiler, while old, doesn't have a permanent pilot light.

I don't think the OP has tested their gas meter yet, so it could possibly be a faulty meter? That's quite a long shot.

We also have the variable daily pattern while they were away, a faulty meter or leak, or indeed a constantly running tap) would more likely lead to a steady loss of gas?

Perhaps a neighbour has secretly teed off the gs supply after the meter?!

Presumably the OP could confirm it is the boiler by switching it off for 12 hours and checking no gas has been used!

Herbyme

DeeQS said:

I moved into a new house in Jan and noticed that when our hot water was on, the boiler would run permanently. 

Turns out we had a fault thermostat on the cylinder. It caused the boiler to just run at a low kWh usage the whole time.

DeeQS, how did you find out the cylinder thermostat was faulty? I'm a bit suspicious of mine, it's over 20 years old, plus the dial is so tiny you could breathe on it and change the setting 5 deg either way!

welshblob

I'm still intrigued by how this system is configured and I'm no plumber or heating engineer so don't take my word for anything. I have replaced a 3 way valve a few times though (first time v messy) and fitted Hive to my system. 

Observations (not necessarily related to consumption)
1. Two expansion vessels, assume one for heating and one for potable water? 

2. Only a two port valve is visible implying that you can't have CH on its own and DHW also has to be heated. Some older systems are like that but this surely would be a more recent install. However I might be missing some other components like the other grey box under the red expansion vessel. 

3. The Honeywell 2 port valve body looks quite new so assume that has been replaced recently? Also note that it is in auto setting so should be working and a quick test would be to see if both pipes to it are hot when just the DHW is on i.e. it would be allowing flow through the CH which wouldn't be correct. 

4. The Honeywell 24 hr controller below the boiler might be a st699b1002 and for some reason seems really expensive on ebay to buy. If that failed I'd probably just replace it with a cheaper Drayton 7 day controller although not sure of any technical reasons not to do that. Also note its got blu tack on the controls which I assume is to stop the far right modes being selected? 

5. Appears at some point the room thermostat has been replaced with a more recent Drayton timer. I assume this is where the CH programmes are controlled from with the main Honeywell controller just set to on for CH? Goes against my statement re 2 port valve in point 2 as that would turn on the DHW as well. Also not sure why you would improve the thermostat and just not replace the original controller and leave the thermostat fairly dumb/simple? 

Just my thoughts and would be interested to hear any plumber / heating engineers comments as I expect there are many ways to configure these heating systems. Would also like to know if reducing the DHW timer windows has seen any savings on consumption. 

DeeQS

Herbyme said:

DeeQS said:

I moved into a new house in Jan and noticed that when our hot water was on, the boiler would run permanently. 

Turns out we had a fault thermostat on the cylinder. It caused the boiler to just run at a low kWh usage the whole time.

DeeQS, how did you find out the cylinder thermostat was faulty? I'm a bit suspicious of mine, it's over 20 years old, plus the dial is so tiny you could breathe on it and change the setting 5 deg either way!

We noticed that if the hot water was on, from a timer, that the boiler would run for the entire duration of the time. This happened even if we didn’t use any water.
I went into the loft and found the dial for the hot water temp and turned it all the way down to 40c and the boiler was still running. The boiler water was set to 60c and the hot from the taps was very hot.
the only way to get the boiler to turn off was to set the hot water temp on the cylinder to 30c. 

Coffeekup

On the plus side when you figure out where you gas usage is going and reduce or fix the issue, gas prices may stabilise.

FYI:
https://forums.moneysavingexpert.com/discussion/6384372/180-a-year-pilot-light#latest

tiya1990

OP here again - Thank You everyone for your helpful comments - I have been doing some detective work and will post some readings. ( BTW - very unpopular at home with OH and teenagers as I am timing their showers - how long oven and microwave being used etc ! ) 

CH is ofcourse switched off . Only gas usage is showers and hob,

A) HW - I found that hot water was being used 8 hours per day - 2 hours in the AM 6.30-8.30 and 6 hours in the evening 4.30 - 10.30PM. Given that no one has a shower in the AM - I have trimmed that down to 1.5 hours and 3 hours ie 4.5 hours ie 44 % reduction in HW times  . Everyone's shower is generally in the evening and around 10 min each - so 40 min altogether -
Could I reduce it further ? 


Readings in kWh - 
For the 3 days that I checked 29/08 - 31/08 - before reducing HW -
AM usage was 3.8 / 6.4 / 4.2 / 10.1   ( for 2 hours ) and
PM usage was 20.2 ( on 29th Aug )  / 10.5 / 10.7  ( for 6 hours ) - I can't explain the 20.4 kwH figure on Bank Holiday - we had gone out for a meal so no cooking  .

Since 1st Sept - when I have reduced the HW times - 
AM - for 1.5 hours - the figures are 4.2 / 5.6 / 8.0 kWh
AM -    for 3 hours - the figures are 15.6 ( no reason - no cooking ) / 6.0 / 11.8 ( hob used for 3 hours ) / 12.5 ( hob used for 1 hour ) . 

So the total gas usage in the last week is 24 / 17 / 15 / 26 / 10 / 17 / 21 = 130 kWh ( where 4d in the week had 44 % reduced usage ) 

For comparison , in the previous week usage with 8 hours HW  was  12 / 16 / 18 / 15 / 16 / 20 / 19 = 116kWh ( and 126kWh the week before ) 

Can there be this much variability from day to day - at the same times when HW alone is on - without any obvious cause ?


B  )  Pilot light and electronic ignition- has been mentioned -  the manual talks about a ' sight glass ' but does not mention a pilot light. I have heard the boiler switching on relatively loudly at 6.30am and 6pm when HW is set to come on. 

At this time a blue light comes on for around 2 min maximum then both the boiler sound and the ' light ' goes off. 

Interestingly , the boiler also comes on at other times randomly though not for more than 5 minutes at a time. 
So far , I haven't noticed this happening outside of the HW times.

C) I have noticed that the Smart Meter starts recording gas consumption 30 min before HW is due to start ie from 6am and 5.30pm - is this the norm ?

D) The setting on the boiler has been mentioned by ' Magnitio ' - this was set by the Servicing Engineer at 2 - the manual says it should be 3 for summer and 5 for winter. 

E) ' welshblob ' - has mentioned ' checking the thermostat on the hot water tank ' - this is now set at 45-50 deg - is there anything else I should be doing ?

F) Radiators are not getting hot so I am presuming that the three way valve is working ??
Regarding the above  installation - these were installed > 10 years ago before we moved in . 
'macman' mentioned that the boiler is likely to be around 20 years ago so possibly the above are from the same time ?

G) One of the above is an immersion heater but this is always switched off. 

H) No leaky tap that I can see. 

We will hopefully have a heating engineer coming in the next week or so . 

Reducing HW has not reduced gas consumption unfortunately though I will continue pegging away - any other suggestions folks ?