Is my boiler being choked of gas?

[Mrast]

Hi all.

Struggling with what I believe to be a high Gas bill last month (£97 for nov-dec, heating only on for 6 hours a day)

Reading around and found someone saying to check how long it takes for gas meter to do a full turn of dial (imperial metre measuring in cubic feet)

I timed it at 83 seconds. So did 1093 / 83 which gives me 13.16 kw input.

My boiler manual says max CH input 29.7 kw

Basically by heating goes on 630-830am and 6-10pm each day last month and the boiler fires for the whole time the heating is on even when th rooms are warm.

Majority of rad trv on setting 3.

Could the 13.16kw be the reason why? Is it not getting enough gas and having to burn what it does get for longer?

The meter reads about 2.6 more each day I check it after heating has gone off.

I hope this makes some sence?

Boiler is a Vaillant Turbomax Pro 24
3bed semi - excellent loft insulation but no cavity yet (being done in 2 weeks)

Thank you

 

[garrywhite]

Hi, how much did you pay this time last year?

 

[Mrast]

I didn't I only brought the house in the summer.

But looking at the British Gas app on my iPhone it is quite startling as it shows me the readings the previous owners had:

2 Nov 2007 - 7 Feb 2008 they used 3681 kwh ( meter readings 1097 - 1215)
6 Nov 2008 - 9 Feb 2009 they used 3529 kwh ( meter readings 1391 - 1503)
6 Nov 2009 - 27 Feb 2010 they used 3049 kwh ( meter readings 1622 - 1719)

Now my readings from 24 nov - 22 de. 2180 kwh ( meter readings 1810 - 1879)

And they previous owners were both retired and the chap had an illness so they would have had the heating on a lot longer than me I'll ever know!

 

[garrywhite]

Maybe they didnt have it on as much. I know many that would put on another coat than put up heating. Also they might turn off rads to un occupied rooms.

 

[GrahamM]

Gas rate is only a rough indication of how much gas the boiler is burning at that time relevant to the demand.
If you do not think your boiler is not operating correctly then you need a qualified person to carry out a general service, checking burner pressure, gas rate on full demand etc.

 

[doitmyself]

Could the 13.16kw be the reason why? Is it not getting enough gas and having to burn what it does get for longer?

The Turbomax Pro is a combi boiler, so the size is determined by the Hot Water requirement. Is your hot water OK, i.e hot enough and fast enough? If it is, then your boiler is getting enough gas.

When did you do your timing check on the meter? Was it first thing in the morning, when the boiler first came on, or in the middle of the day when the house had warmed up?

The boiler will only provide as much heat as your radiators can give out. You can get a good ide of what this adds up to by using the Stelrad Elite Catalogue

You can also work out how much heating you need by using the Boiler Size Calculator. Deduct 2kW from the result and then compare with your radiator total. Do it with and without cavity insulation to see how much you will save.

 

[GrahamM]

The Turbomax Pro is a combi boiler, so the size is determined by the Hot Water requirement. Is your hot water OK, i.e hot enough and fast enough? If it is, then your boiler is getting enough gas.

Just because the householder thinks their hot water is hot enough does not indicate the appliance is getting fed the correct amount of gas.
Only a gas rate, operating pressures etc. in line with manufacturers requirements will determine this.

 

[doitmyself]

Just because the householder thinks their hot water is hot enough does not indicate the appliance is getting fed the correct amount of gas.
Only a gas rate, operating pressures etc. in line with manufacturers requirements will determine this.

I agree. But if OP was only getting 13kW when the HW was on, I think he would have complained about that as well. After all, 13kW will give a 35C rise at a flow rate of 5.5 litres per min, which is not really adequate.