Back boiler removal in East Kilbride: what actually happens

If you live in Westwood, Greenhills, East Mains or the Murray, there is a fair chance you still have a back boiler — a gas boiler sitting in the chimney breast behind the living-room fire, feeding a hot water cylinder upstairs and fed in turn by one or two tanks in the loft.

They were the standard arrangement when much of East Kilbride was built, and most of the ones we remove are between thirty and fifty years old. They ran reliably for a long time. But they operate at roughly half the efficiency of a modern condensing combi, they heat a stored tank of water whether you need it or not, and parts are now genuinely difficult to source.

People are usually put off converting because they do not know what the work involves. So here is the whole thing, honestly, start to finish.

Morning: removal and first fix

We arrive between 8 and 9am and put dust sheets down through the living room, hall and stairs — this is a dusty job and we would rather over-protect than apologise afterwards. The gas and water go off first.

The fire comes out, then the boiler behind it. This is the part people find surprising: there is often a substantial void behind the fire once the unit is out, and in older properties there can be decades of soot and debris sitting in it. We clear it, then sweep the chimney properly.

The chimney is then capped and vented. That second part matters more than it sounds. Capping a chimney without ventilation is one of the most common causes of damp appearing in a chimney breast a year or two later. A vented cap lets the flue breathe while sealing it against rain and birds.

Upstairs, the cylinder is drained and removed, and the loft tanks go with it. All the redundant primary pipework comes out too. Then we run the new gas, water and condensate pipework to wherever the new combi is going — usually a kitchen wall, because that is where a legal flue termination, the gas run and the water main most easily meet.

You will be without heating and hot water from mid-morning until the system is recommissioned. If anyone in the house is elderly, very young or unwell, tell us when you book and we will leave temporary heating at no charge.

Afternoon: the new boiler

The afternoon is the boiler itself. The unit goes on the wall, the flue is installed and sealed, and the system is filled and pressurised. Then comes the power flush.

This is not an upsell. An old open-vented system in a 1970s house will have decades of magnetite sludge sitting in the bottom of every steel radiator. Put a modern condensing boiler on that without cleaning it out and you will block the new heat exchanger within a year or two — and the manufacturer will decline the warranty claim, quite reasonably. A full power flush is included in every conversion we do.

After the flush the system is dosed with inhibitor, and a magnetic filter goes on the return if you have chosen to add one, to catch anything that comes loose later. Then we commission the boiler, balance the radiators so the back bedroom heats at the same rate as the living room, and set up the controls with you at the kitchen table.

What we do not do

We leave the hearth, chimney breast and airing cupboard capped, safe and tidy. We do not plaster and we do not decorate. Some firms imply the wall will be finished; it will not be, by us or by them, and we would rather say so before you book than after.

You will want a plasterer for the chimney breast if you plan to flatten it, and the airing cupboard usually needs nothing more than a shelf.

What a back boiler removal costs in East Kilbride, and what you get back

A back boiler to combi conversion starts at £1,695 fully installed, and usually takes a day. That includes the removal, the chimney capping, the cylinder and tanks, the gas upsizing where the run needs it, the power flush, the new boiler, all certification and taking everything away. A magnetic filter is an optional extra at £95.

What you get back is an airing cupboard, a usable chimney breast, hot water on demand rather than on a timer, and a system that stops paying to keep a tank hot around the clock. For most of the East Kilbride homes we work in, it is the single biggest improvement available to the heating system.