The focus of our case study is a listed building in Westerham, Kent, which was once the residence of William Pitt the younger.

Westerham is a small town steeped in history, and features Chartwell, home of Winston Churchill, Downe House, home to Charles Darwin, and Squerryes Court.  Chevening, the deputy prime minister’s estate, is just down the road.

Featuring timbers that are believed to date back to the 13th century, in more recent times William Pitts’ former house has been an upmarket restaurant, and an Indian fine dining eaterie.

Pitts Cottage in the days when it was Kinara, an Indian restaurant

The present owners purchased the property in a state of dilapidation, and set about a total renovation.

Pitts Cottage after the restaurant had closed down

Many of the period features were retained or where time expired, sympathetically renewed in a manner acceptable to English Heritage.

Hot Water & Central Heating Ltd were asked to provide a design and specification for complete new heating system and hot water services, all to be sited in a below ground cellar area in the original building.

Because the cellar had no mains drainage, we used a thermal store as the energy source for the hot water.  We would normally use unvented cylinders for this type of domestic application, but the arrangements in sealed subterranean locations do not allow for a reliable expansion relief system.

Joule thermal store and TWS water accumulator (before we added insulation)

All water was to be mains pressure, and since the houses along this stretch of road share water supplies, we augmented the water supply to the heatstore with a TWS accumulator system.

Another view.  The black insulated box contains the plate heat exchanger and pump for hot water

The rear of the property was extended at ground level to include a modern kitchen complex and rear patio.

A Worcester Bosch CDi system boiler was fitted within the cellar, featuring their recent high level expansion relief modification accessory.



Worcester 35CDi system boiler

New Evohome wiring and pipe insulation now in place

We installed a full Nu-Heat underfloor heating system in some old ground floor parts of the house, and the new kitchen and utility areas, comprising 6 zones of heating.

The new underfloor manifold, hidden under the stairway

In the entire hallway the old clay tiles were dug up, insulation, underfloor heating and screeding laid, and then the tiled floor relaid on top, exactly as it was before.  Except much warmer!  Expansion joints were fitted as necessary.


Main hall was excavated, insulation and underfloor heating added, then screeded and tiled. Picture shows our edge insulation going in

Floor now relaid, picture shows Nu-Heat underfloor manifold and Evohome UFH controller

In the remaining parts of the property we fitted Vogel & Noot panel radiators.

Tim walking across insulation layer in new extension, preparing to lay underfloor grid


Laying pipe supports, yellow sheathed gas pipe has been run below insulation; it is jointless so should never leak.


English Heritage allowed a large extension at the rear of the house. All the new areas have underfloor heating


Underfloor grid awaits screeding

The whole system is run by a Honeywell v3 Evohome, giving 12 separate zones of individual heating control across the property, together with hot water monitoring and control.

Evohome controller

Evohome controller

The whole property has been transformed into a beautifully designed residence, mixing the old and the new.  All  credit to the architect and the customer; we are proud to have played a small role in the work.

NB: This is the second large project we have carried out for this customer’s family, there is a Viessmann Vitocrossal 300 commercial installation in a large office complex nearby.