Lochinvar keeps hot water flowing in Sky Garden

Key Equipment Supplied

Project details

Boiler and water heater manufacturer Lochinvar is supplying a plentiful amount of hot water to two prestigious restaurants hovering over London in the Sky Garden at the top of the iconic 20 Fenchurch Street building.
At a 160m (525 feet), the building which is also known as the Walkie Talkie because of its distinctive forward leaning shape, is London’s fifth highest building and cost £200m to build. The glazed sky deck, with its magnificent views of the city in all directions, is open to the public and contains the highest landscape garden in Europe. It sits above 34 storeys of commercial office space.
The Fenchurch restaurant and Darwin brasserie, managed by Rhubarb who also run the bar on the sky deck, are catering for three times the number of covers they anticipated on opening last January. The original estimate was for 250 diners per day, but this quickly rose to 750 due to the immediate popularity of the sky garden.

However, the hot water needed for washing up and cleaning, as well as the restrooms, has continued to flow thanks to the use of a Lochinvar 150kW LOK packaged plate heat exchanger (PHE) and 500 litre storage vessel.


Although the curved upper floors of the new London landmark building are extremely spacious – and reverse the standard approach of tapering buildings by having the upper floors larger than the lower – conditions are much more cramped behind the scenes in the restaurants’ plant room.
“As with all restaurants, it is important to maximise the front of house space so our building services team [led by Hemel Hempstead-based m&e contractor Wilden] had to ensure all our essential equipment fitted into a pretty restricted space,” says Rhubarb’s facilities manager Rob Hutton.
As a result, it was agreed that an indirect hot water system, drawing heat from the landlord’s central boilers and primary LTHW service, would be the best solution.

“We were concerned that the tripling of our anticipated amount of business might mean the hot water system would struggle to cope, but it has not let us down – we are delighted,” adds Mr Hutton. “Restaurants are like swans – they appear to be sailing along serenely – but behind the scenes everyone is paddling like mad. That is very much the case at the Fenchurch and Darwin; so it was absolutely vital that the hot water system could keep up.”
As well as the compact arrangement, going for an indirect heating solution using Lochinvar PHEs and storage vessel avoids the need for a flue, which gave the installation team extra flexibility when siting the equipment.

Lochinvar, primarily known as a manufacturer of direct gas-fired water heaters, also offers indirect solutions these days; including 11 different sizes of PHE, with hot water outputs from 872 to 9,544 l/h at 50 deg C temperature rise.
A key feature of the range is the enhanced four-port valve, which speeds up delivery of the hot water and improves system efficiency. When the system is up to temperature and hot water demand is satisfied, the valve will close allowing both the primary pump and the PHE pump to continue cycling. As soon as there is demand for hot water, the four-port valve opens and provides hot water instantly; there is no need to wait for the water to be reheated and recirculated to the PHE.

This is particularly useful where there are intermittent periods of high demand like a restaurant. With standard three-port valves, extra components would be required on the LTHW circuit to maintain the same speed of delivery and avoid the creation of a ‘dead leg’. Each model is also available with either single or twin primary LTHW pumps.

Lochinvar PHEs are built from 316L individual stainless steel plates and have efficiencies of up to 98%. Storage capacity is often an important consideration especially when the application in question is subject to high peak hot water demand. The storage options available range from 312 up to 2,820 litres.

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