Some people have asked why I said the cost of replacing a boiler was likely to be nearer £5,000 than the £1,367 you suggested (22 January, page 24) or the retail cost of about £750

I have a quote for my house, a three-storey, three-bed townhouse, built about 1980. The heating system has a wall-hung boiler running at 79% efficiency. There is a central programmable wall thermostat and a programmable boiler controller.

The replacement condensing boiler can be hung in the same place, but regulations require the adaptation of the flue outlet. The boiler needs a condensate drain. The gas pipe needs replacing with a larger diameter one.

Regulations on installation require a fully pumped hot water system in parallel with the radiator system. That involves controls, a new pump and a further flow pipe to the hot water cylinder. All pipes must be insulated.

Regulations also require zone controls on the heating. The quotation supposes individual radiator thermostats. Because of the heavy disturbance, it becomes necessary to powerflush the system – this involves some alteration to the radiators pipework and we are also required to have the ME bonding updated. The gross price quoted, before grants but including VAT, was £5,351.

When putting in new pipework there will be damage to the existing tiling. The kitchen and bathroom will probably have to be retiled, and have plaster damage made good and repainted. My guess as to a sum to cover consequential damage is £2,000.

Some people have asked why I said the cost of replacing a boiler was likely to be nearer £5,000 than the retail cost of about £750. Here’s why...

Ian Macpherson

My conclusions: I might get a 15% saving on an annual gas cost of £1,100, for a total expenditure of, perhaps, £7,000.

On the other hand, replacement of wooden windows with aluminium double glazing (£6,000 from a local firm) would save a five-yearly repainting bill of £2,000. The energy savings for me would be incidental, but for the nation a useful contribution.

Strange that replacement double glazing is seldom pushed by the government.

Ian Macpherson