Plumbers & electricians in Sevenoaks

The town stands on the Greensand Ridge, the band of sandstone that crosses Kent from west to east, at the point where the roads from the north gather before climbing over it. Knole’s deer park runs up to its eastern edge. For centuries it was a market town serving the big estates, and the railway came late. A line reached Bat and Ball in 1862, and in March 1868 the South Eastern Railway opened a more direct route through the North Downs, with a station at Tubs Hill that is still the town’s main one. After that the brick villas followed. Tubs Hill, Granville Road and South Park filled with substantial houses for the families of London merchants, and the Kippington estate, bought in 1864 by the tea importer William James Thompson, who built St Mary’s church there in 1880, was laid with large detached houses along new roads. Kippington Road is now a conservation area.

The west side grew in a different way. Riverhead is an old village in its own right, with a Decimus Burton church of 1831, and beside it the Darent runs through Chipstead Lake, dug for sand from the nineteen thirties onward; the Lakeside estate went up on the old Marley Tiles site in the mid nineteen nineties. Dunton Green made bricks and tiles for centuries and became its own parish in 1908. Between the wars large estates, Chipstead among them, were sold off, and houses and chalet bungalows went up on generous plots.

So TN13 is heavy with big houses. Most now heat with a gas condensing boiler.

Condensing boilers that never condense

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A condensing boiler earns its efficiency in one specific way. The hot gases leaving the burner carry water vapour, and if they are cooled far enough that vapour condenses on the heat exchanger and gives up the heat it was carrying, heat an older boiler simply sent out of the flue. For natural gas that happens when the gases drop below their dew point, about fifty five degrees, and what cools them is the water coming back from the radiators. So the figure that matters is not the flow temperature on the dial but the return temperature, and the return has to come back below roughly fifty five for the boiler to condense at all. Nesta, which ran the Money Saving Boiler Challenge, found that most condensing boilers in the UK are set with a flow temperature of seventy to eighty degrees. In a big Sevenoaks house that is often how the old cast iron boiler was run before it, and the installer matched it so nobody would notice a difference. With the flow at eighty and a large house pulling heat out of the water slowly, the return comes back well above the dew point, and the new boiler spends its winter running like the non-condensing one it replaced. It still works. It simply never delivers the efficiency it was bought for.

What the household sees is radiators too hot to keep a hand on, rooms that overshoot and then cool, and a boiler that fires, stops and fires again every few minutes. That stop and start is called cycling, and it adds wear. The plastic condensate pipe outside, which on a boiler that is condensing well carries a steady drip on a cold day, barely wets.

The first step costs nothing. Turn the heating flow temperature down, sixty being the figure Nesta suggests as a start, and live with it through a cold week. If every room still reaches temperature, try lower. Where the boiler supports weather compensation, an outdoor sensor lets it set the flow from the weather, running cool on a mild day and hotter only when it must, and load compensation does something similar from the house’s own demand. The honest caveat belongs to exactly these houses. A Victorian room with a high ceiling and a single radiator sized for eighty degrees may not keep up at sixty, and when one room fails the answer is that room, not the whole house back up to eighty. Whether a given house condenses comfortably at a lower setting is a test done in that house, not a rule.