The photo shows a yellow splodge against the bottom setting, where an arrow should be. This suggests that the boiler has been set to max. You can check this by measuring the gas consumption rate.
With the boiler running, time how long it takes for the dial hand on the gas meter to do one revolution (or count how many revolutions and fractions the hand does in one minute). You also need to know if your meter records in cubic meters or 100's of cubic feet - it will say on the meter. From this information you can calculate the hourly gas consumption. If your boiler is set to max it will be 1.8 cubic meters per hour or 62 cubic feet per hour.
Don't forget that your boiler is at least 18 years old, so it will not be as efficient as when new - unless it has been well maintained and had parts replaced. This means that, even if the gas consumption is at max, the boiler may not be giving out the same output as when it was new (14.7kW) - it will probably be less.
If your boiler is set to max, there is nothing much you can do - apart from install a bigger boiler. However, I doubt if that will be necessary as seven radiators will be unlikely to be more than 10-11kW, which still allows 2-3kw for the hot water.
If the consumption is lower than the figures given, post your results to find out what the boiler is set to.
You can find the approx output of your existing rads by using the
Stelrad Elite Catalogue. The sizes may not be exactly the same, but you can usually find one which are near enough. This will tell you what size boiler you need (or if you need a bigger boiler
).
If you need the boiler setting changed your will need a
Registered
Gas
Installer, i.e a CORGI registered person, to adjust the setting.
