Steam technology at its finest
Kempton’s pair of triple-expansion steam engines were at the cutting edge of water pumping technology when they were installed in 1927-28 to supply 39 million gallons of water to North London.
In the beginning…
The waterworks at Kempton started life in 1897 as the New River Company, with two holding reservoirs supplying 12 slow sand filter beds. Five Lilleshall triple-expansion steam engines were installed – two to lift water from the Thames to the reservoirs and three to pump it on to Cricklewood. The steam was supplied by six hand-fired Lancashire boilers. In 1915, a narrow-gauge railway was constructed to bring coal for the boilers up from the river at Hampton click here. By 1904, the New River Company had been incorporated into the Metropolitan Water Board along with seven other water companies and, in 1929, the MWB applied to the College of Arms for the coat of arms displayed on the far wall of the engine house as you enter the building.
The Triple House opens
London’s demand for water was growing and as new suburbs sprang up in the aftermath of World War I, the MWB decided to build the new engine house at Kempton. Work began in 1927 and was completed in 1928, when the two Triples you see today were commissioned by Sir William Prescott, then chairman of the MWB. Because the five Lilleshall engines were still in service, the new Triples were numbered 6 and 7, and were named after Sir William and his wife Lady Bessie respectively. Space for a third Triple was allowed for but this was never installed.
Built by Worthington-Simpson of Newark, near Nottingham, the Triples were brought down in component form by rail and assembled on site with the use of a 20-ton gantry crane, which can still be seen operating today. The maximum payload of a railway truck meant that no one component could weigh more than 16 tons. Such was the size of the Triples that Worthington-Simpson was not able to fully assemble the engines at their Newark works and had to content themselves with doing a test assembly in two halves.
Turbines add pumping power
Instead of the planned third Triple, a pair of steam turbines were added in 1933, while the five Lilleshall Triples continued operating in an adjacent building. The Triples each produced 1008 horsepower, pumped 19 million gallons per day against a 200 foot head and, at 62 feet high, are the largest ever built in the UK. They ran 24 hours a day, seven days a week, with steam provided by six moving-grate boilers. In 1963, the site employed 144 men and delivered 86 million gallons of water a day.
In 1945, the two-foot narrow-gauge railway was scrapped and, in 1968, the Lilleshalls went too, their boiler house pulled down and the reservoirs abandoned. In 1980, the moving-grate boilers serving the Triples were scrapped and the Triple House finally closed down. Electric pumps, installed in the old Lilleshall House, now deliver 75 million gallons of water a day, operated by a site staff of just 14.
Practically everything from the Triple House’s working days has survived, including not only the engines and the crane, but the original tools, the DC electrical control board, the flow meters and the dials used to monitor each engine’s output.
After building closed in 1980, English Heritage declared it a National Monument and, along with its contents, was listed Grade II*. In 1995, the Kempton Great Engines Trust was formed with the aim of restoring and maintaining this magnificent piece of steam heritage for posterity.
An army of volunteers spent the following six years and 100,000 man hours restoring Triple No.6 before HRH The Prince of Wales was invited to restart it in 2002. A further two years were then spent preparing the building for the public opening and the first steaming weekend took place in October 2004.
Ten years on…
A decade has passed since those first visitors stood in wonder as the awesome 1,000-ton Triple’s twin flywheels began to turn for the first time in over 20 years. Since that momentous weekend, thousands of men, women and children have spent a day marvelling at one of Britain’s greatest feats of steam engineering. But the work is not over and Kempton’s volunteers are still busy, maintaining the Triple and restoring other items in the historic engine house, including one of the steam turbines.