Boiler or Gas Meter - excessive gas usage

[FooManChu]

Hi

I've read a few topics already on this subject and have now encountered it my self. I had a new Baxi (sorry don't know the model at present) Combi fitted 18 months ago to a 4 bed detached (1930's) and last years Jan to Mar gas bill was reasonable and not excessive given the readings. However, this year the same time period has resulted in my gas bill reading for this period to rise by 4 times. Now I know Gas prices have soared but this is a reading issue, not a price issue.

Having read a previous comment about testing the Gas meter by checking the revolution of the main dial I have checked mine. As well as a digit dial I have an arrow dial which has an 0.5 beneath it.(o.5 cubic meters?) With the boiler on, this dial turns two revolutions for every 70seconds. Does this sound to be correct?
We had the meter checked FREE by Transco last year as we suspected a leak at the time but the Transco chap declared it working fine after a few tests. He did say however, that the boiler we had installed was a "big-un" I've since turned it right down....could this have been wrong or me to do this? There are separate dials on the boiler for Water and Heating and I turned these to half way.
We have the heating on no more than 20degrees via thermostat and have those stats on every rad in the house. Not every rad is on all the time. With the hot water running or the heating system on, the dial turns rapid. With the boiler off but the gas hob (the only other gas appliance we have) running, the dial turns very very slowly. The boiler does seem to affect the dial more than the gas hob...could the boiler have developed a fault? If so, what fault would that be if I was to get it inspected?

Any advice or assumptions would be appreciated.

AH

 

[gazthepottertonengineer]

Its more that likely down to the fact that gas prices have increased by 30-40%

 

[FooManChu]

I know they have increased, but taking my last years readings for this period of say, 100 units per quarter, now this years readings for the sam period are 400 units. So are you saying that the gas people now push out a faster rate of gas? I think not. More units means more consumption not price increases.

Cheers

AH

 

[ollski]

Big combi uses an obscene amount of gas when running hot water and it fires up almost constantly while there is a hot water demand.

 

[Gasguru]

One revolution of the test dial on the meter shows 1 cubic foot of gas consumed.

Therefore if 2 revs takes 70 seconds this equals 35 seconds per cubic foot.

Gross Kw input to boiler = 1100/35 = 31.4 Kw

Check with the boiler manual but this seems resonable for a mid range combi (if the figures in the manual are quoted nett then look for 28.3 Kw(31.4/1.11))

Generally these measured figures should be either -10% to +5% of the book figure.

When you time the dial check the burner is not modulating down (reducing heat output) by looking at the flame height (it should not reduce), otherwise you will get a false reading.

Do you have a warmstart or other feature on the boiler to maintain it in at hot temperature? Some are poorly designed and will fire the boiler up even throughout long periods when there is no hot water demand. This is exacerbated if the boiler is in a loft or equally cold place.

 

[FooManChu]

ok, so are there any special guidelines to what settings a large combi is most efficient at? 9 rads, thermostat above the rad in the hall set to 20 (btw, I don't have the heating on at the present time - too warm).

I use the Thermostat to regulate the usage and not the built in timer on the boiler. Would using the timer help?

Could there be a problem with the meter? Or the boiler?

The boiler has a frost stat installed set to 5% (I think the installer said) and the boiler is located in the garage. However, I am concerned based on 2 years of running why all of a sudden I have an increase in meter readings.

AH

 

[htgeng]

Big combi uses an obscene amount of gas when running hot water and it fires up almost constantly while there is a hot water demand.

Agreed. Tell us if your hot water usage has changed in the last year? How long do you have to let the tap run before you get hot water? Do you have baths/showers?

For most typical situations, a combi boiler is very uneconomical - its like flooring your car accelerator everytime you start from a a traffic light!

A better solution is stored hot water, whether that be unvented, vented or thermal store. If you continue to use a lot of gas, it might not worth adding one of these to your system. It wouldn't take many years to pay back your gas savings.

 

[Gasguru]

Does the gas consumption check out with the manual?

What boiler make/model is it.

Is there a pipe thermostat fitted, a frost stat on its own is not sufficient and will increase bills.

Do you have a correctly located room thermostat and TRV's?

Use the timeclock.

Is the current bill estimated or a real reading.

 

[plastered]

Big combi uses an obscene amount of gas when running hot water and it fires up almost constantly while there is a hot water demand.

Just had an obscenely high end of year bill sent through, now that I've seen this I think I understand why. Thanks, v.useful bit of info. B*****y Baxi 's.
...and so, I will now go and add to next years bill by firing up my gas guzzling combi in order to run my self a bath!

 

[Agile]

Oh Dear !

None of you have used the Met Office figures.

If you compare the average diurnal temperatures during the period a year ago you will see that we have had a much colder winter and although we went back to average temperatures last Thurs/Fri we are back to well below average temperatures.

Today I wore a tee shirt and a long sleeve think shirt and was just about comfortable. Last Friday I was sweating in a tee shirt and hot in just a short sleeve shirt during the evening.

You should blame Tony Blair for global warming! ( Yes I know its not his fault its all those with 4 x 4 s to pick up the kids and its just a cold winter and global warming is only 3° during the last 50 years but.....)

Tony

 

[FooManChu]

ok, some further details.

My boiler is a Baxi is a 133HE+ installed over a year ago. I checked my meter readings last night and in a week I have gone through 2 units without central heating but with using hot water and gas hob usage. So the boiler (aka Heating) does make a huge difference.

--How long do you have to let the tap run before you get hot water? Do you have baths/showers?

I use an electric shower mostly and so a bath is rarely used. I did read that running the hot tap slowly will reduce gas usage as it reduces the flow from the boiler allowing the boiler to heat the water faster. Correct or dumbfounded?

--Does the gas consumption check out with the manual?

I'll have to look into this further.

--Is there a pipe thermostat fitted, a frost stat on its own is not sufficient and will increase bills.

There is no thermostat fitted on any pipes to my knowledge.

--Do you have a correctly located room thermostat and TRV's?

I have TRV's on very rad but a conflict of interest as to whether they work or not. The gas engineer who installed the system dismissed them as useless yet the Transco engineer who came and inspected for leaks told me they worked.(as in were useful)

--Use the timeclock.

YES, I believe this may be an issue. Last year I remember using the clock more but was told a while back that using the thermostat in the hall would be better to regulate the temperature/usage. The thermostat is located above the hall rad and the Transco engineer said is should not be positioned there but further up the stairs? Any comments on this anyone????

Can a more programmable clock be fitted to a 133HE+? So that we could have a setting for the weekdays and one for the weekend. This cannot be done with the present clock.

--Is the current bill estimated or a real reading.

No, its an actual that I have taken myself and double checked. I will be monitoring it in future when the heating is switched back on again when its cold.

Cheers for your advice so far.

AH

 

[ChrisR]

You can use a programmable thermostat which allows different temps at different times during the week, with smoothing algorithm to avoid temperature overshoot.

I'd be checking the gas pressures supplying your boiler to make sure all is as it should be, but it sounds like you've just got used to a warm house!

 

[FooManChu]

I will be monitoring the meter in future.

I guess its call Transco again if I want to measure the pressure?

AH

 

[Gasguru]

AFAIK there are two versions of the 133HE+ the early ones had a recuperator and later ones a single primary heat exchanger. The book figure for the later version shows 45.45 Kw gross.

Therefore the boiler is either modulating down during the reading (due to reduced water flow/low water pressure/undersized water pipes etc) or the gas pipework is undersized and the boiler is not producing its full output.

The boilers own frost protection will operate at 8 Centigrade.

A frost stat should also have a pipe stat. If the frost stat turns the boiler on due to the reduced ambient temperature a pipe stat will then turn it off once the return pipework has reached say 15 Centigrade. Otherwise the boiler will fire untill the room warms up.

TRV's on ALL radiators are a recommendend control method for this boiler, but there must be no bypass valve fitted. The boiler has an integral flowswitch to turn the boiler off if all the TRV's have shut down.

Either dis-connect the room stat OR move it to a suitable location in the hall and remove the trv from the hall rad and fit two lockshields to prevent adjustment. Adjust this rad so the hall is the last place to get up to temperature.

It should be straightforward to add a 5 and 2 day external timeclock.

The boiler has "intelligent pre-heat" ie it logs hot water usage and only pre-heats when required - I would not have though this should add too much to the gas bill, however Baxi and intelligent design don't really go together!. It can be disabled if neccesary.

 

[FooManChu]

Thanks for your input.

I don't have (apologies for saying all rads have TRV's) a TRV in the hall or in the bathroom radiators.

Another question!

Do you have to balance a sealed system at all?

Regards

AH