Andrews supports solar-power

Oil-fired storage water heaters from Andrews have been incorporated into an innovative renewable energy commercial solar powered water heating system recently installed at County Hall in Bedford. Bedfordshire County Council has strong environmental improvement policies and each year selects as many projects as possible that fulfil this commitment.
In 2004, Mouchel Parkman, Building Management Consultants for the Council, reported that since 1965 when the building and its services were designed, energy efficiency technology for space heating and hot water generation had advanced to such an extent that by replacing some of the 38 year old plant, significant savings could be made on running costs. Their recommendation was for the space heating and domestic hot water load to be decentralised and that the smaller of the three boilers installed in 1966 solely for hot water production be replaced by a solar powered system from Genersys, backed-up by Andrews independent oil-fired storage water heaters to raise the final water temperature to the level required.

Building occupancy is approximately 1000 employees plus visitors and its year round demand for hot water was outstripping the seasonal space heating cost. The main building has six floors each provided with four toilets and four wash-basins and there are a further six toilets with wash basins in the Riverside annex. There is also a commercial kitchen serving the canteen which is open daily from 8am to 5pm providing a minimum of 160 covers for lunch in addition to lunch platters for meetings and seminar rooms. Consequently hot water demand is constant throughout the day for food preparation, washing up machines and washdown.

Peter Murphy of Mouchel Parkman explains: “In the basement plant-room two of the original oil boilers remain for space heating together with one of the two previous hot water cylinders. This now stores mains fed cold water before it is preheated by the solar panels and fed to the two Andrews OF73/654 direct-fired water heaters, each providing 2,970 litres output when raised through 44ºC, and regaining full capacity in less than eight minutes. With the original plant the mains water would come in at anything below 10ºC and the boiler would have to raise it to the required temperature of 60ºC. The new direct fired water heaters no longer heat the primary water which is now mains fed via the cold water cylinder to the solar powered panels where it is pre-heated in winter up to 25-26ºC before passing onto the Andrews units which raise it the remaining 35ºC. In summer, the solar powered panels bring the primary water up to 48ºC so the water heaters only have to bring the temperature up through 12ºC. So, even on the coldest day energy cost are cut by a third and up to two-thirds during summer.”

Since the solar powered system was installed, the heating boilers have been shut down on 15 May and not restarted until 15 September and in winter the heating boilers were shut down at 17.00 hrs whilst the water heating may run on till 19.00 without wasting energy.

Andrews storage water heaters were selected because they are one of the few ranges on the UK market that include oil-fired models. The optional Correx anodes and unvented kits essential for this installation were supplied as part of the package.

The payback period for this Bedfordshire County Council installation is calculated to be in the region of 15 years at current energy prices. The entire installation was carried out by Mellor Bromley of Leicester.

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