Hi-VEE heat interface:

 

The “heat interface” as Johnson and Starley term their Aquair air handler, is not a new idea. Heat interfaces have always been around in the world of commercial heating for factories, warehouses etc, where they are known as “”air handlers”. Similar but smaller devices for domestic warm air heating systems have been around since the 1960s and made by a firm called Hi-Vee Limited in Crowborough, West Sussex. 

 

I still encounter the HI-VEE heat interface in domestic houses and bungalows and in regular use, usually when I’ve been called in because the heating has failed. The HI-VEE heat interface is a very basic piece of engineering comprising a pipe grid with fins (which looks rather like a car radiator) mounted horizontally in a box, with a large but quiet fan above it. Hot water from an ordinary central heating boiler isn pumped through the pipe and the fan blows air through the fins to create a flow of warm air. The warm air is then distributed through the warm air ducts to heat the whole bungalow or house. (These 1970s heat interfaces seem to be installed mainly in bungalows - I’m not sure why.) 

 

The fan inside the HI-VEE looks like a giant hamster wheel and is driven by a separately mounted electric motor ,via a v belt connecting the two. The most common fault is the v belt simply coming off. The v belt wears with use and becomes loose and eventually jumps from the pulleys. Replacing the v belt is easy and the belt tension needs to adjusted to compensate for wear, then the unit is good for several more years. 

 

This particular HI-VEE was originally powered by a floor standing central heating boiler, probably a Potterton Kingfisher II, but is now powered by a modern Worcester-Bosch wall-mounted condensing boiler just out of view in the top photograph.

 

 

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A large HI-VEE heat interface in a spacious five bedroom bungalow with a separate boiler room, built in 1985. Shown with the front access panel removed.

Close-up of the fan motor showing the v belt and pulley