DATA

HOT WATER HEATING COILS			DATA SHEET



General All heating coils can be manufactured to suit either vertical or horizontal air flow, but the application must be specified when ordering. Coils are designed for ‘Contra-Flow’ i.e. with the water flow connection on the air leaving face of the battery such that the heating medium is flowing in the opposite direction to that of the air. This gives the maximum logarithmic mean temperature difference and therefore the maximum performance. Coils can be designed for ‘Parallel Flow’ but this must be specified at the enquiry stage. One row and two row coils with opposite side connections can be installed with the primary tubes either vertical or horizontal. Coils with more than two rows and one row or two row coils with connections on the same side must be installed with the primary tubes horizontal as shown in the illustration. Hot water coils are available in depths from one to sixteen rows with alternate rows equally staggered, to obtain maximum heat transfer. Heat Transfer Surface The primary tubes are manufactured from solid drawn seamless copper tube. Fins are of the smooth plate type produced from aluminium, vinyl coated aluminium or copper and are punched with self spacing collars. Plain tube coils are available for anti-frost applications or where the pre-heating of unfiltered air is required.
The primary tubes are mechanically expanded into the pre-formed collars thus assuring a good metallic bond between the fins and tubes. This results in uniform heat transfer with guaranteed performance throughout the life of the coil. The tubes are brazed or silver soldered into copper return bends ( where applicable ) terminating in tubular copper flow and return headers each provided with a B.S.P. screwed male connection. Flanged connections are available on request.	Casing The heating surface is housed in a casing produced from galvanised sheet steel. Where the primary tubes pass through the casing, smooth belled holes are provided to permit freedom of movement for expansion and contraction. The casing is produced in channel and tray formation suitably stiffened to prevent distortion. The flanges formed by the casing sections can be drilled for attachment to adjacent components on request.	Testing All Hot Water Heating Coils are subject to an air under water test of 2000 kPa. Where higher working pressures or extreme temperatures are involved coils can be tested up to 3500 kPa or twice their working pressure. Finish Coils with a galvanised steel casing are generally supplied unpainted but special finishes are available on request.