Fan Assisted Trench Heating

Our fan assisted trench heaters have been designed to provide the higher heat outputs not normally achievable by natural convection heaters for a given size and configuration. As a rule of thumb, outputs can be doubled by use of fan assistance.

The use of crossflow fans within the trench casing provide a fast, smooth laminar flow of air through the linear or roll-up grille, without turbulence or intrusive fan motor noise. The advantage of crossflow fans are their small size coupled with high relative efficiency, especially for small pressure and placement. They have a long ‘throw’ of air for direct ventilation, with widely controllable characteristics and extremely low noise. Fan assistance can be applied to any of the trench heater casings featured on this site having overall dimensions of at least 150mm wide and 125mm deep.
Fan speed control is provided by an electronic speed controller switch, usually wall-mounted nearby.
A typical installation would only need the fan to operate at the lower speed setting.

Fan Assisted Trench Heating

The fans are chassis mounted, constructed in zinc coated steel and mount-insulated by rubber type absorption feet. A centrally mounted motor is flanked by two 300mm long aluminium impellers of 30mm diameter. Each trench casing typically would have one of these units fitted.

Motors are of the ‘shaded pole’ type, conforming to BS5000 PT II. Having two field windings, these motors have power consumption of 8.7 Watts and 15.5 Watts respectively. They have a ‘Free air speed’ of approx. 1,900 r.p.m. and 2,300 r.p.m. with corresponding ‘Free air flow’ of approx. 32 L/sec and 39 L/sec. Typical applications within trench heater casings at medium settings, would yield ‘Free air flow’ of approx. 16 L/sec.

Sound pressure levels are remarkably low under normal operating conditions. Acoustic properties of individual rooms can have an influence on actual noise levels recorded.

Trench Heating


Trench Radiant

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