Yes you could get a wireless room stat fitted, instead of the power going from the timing to the boiler, the power goes from the timer to the room stat then to boiler, when the room stat reaches the set temp, it stops the power to the boiler. However, the boiler also has a stat on it which monitors the temp of the water coming back to the boiler, so the boiler isn't really on all the time. A room stat will save you a little money on the gas bill, maybe £30 a year and will come in at(wireless) about £200 fitted, you could also put TRV's on all bar on of your rads, this will save you about the same, but you've got a a gravity fed back boiler, between 30% and 40% of the heat is going straight up your flue and out of your chimney, or to put it another way, if your gas bill is £600 a year £240 of that completely wasted, or look at like this, for every £100 you spend on gas now, with a new boiler you would be spending £60-£65. The best thing to do is cut you loses and buy a nice new condensing boiler, it doesn't have to be a combi so you can still keep airing cupboard, buy a good one like a worcester or glow worm, it will pay for itself in 10 years. Either that or start saving for a new boiler and dont bother throwing anymore money at the back boiler, because your throwing your money down the drain. Hope this helps
LTGF
September 2008