OVERHEAD RADIANT HEATING -

Minimum volume to be heated by each HEAT-RAD heater must be at least:
Model HR.45 / HR.45.FD	130 m3 (4440 ft3)
Model HR.75 / HR.75.FD	220 m3 (7500 ft3)
Model HR.130 / HR.130.FD	380 m3 (13418 ft3)

Size of permanent air vent direct to outside
Model HR.45 / HR.45.FD	95 cm2 plus 35 cm2 per extra 2Kw or part thereof in excess of 6Kw rated heat input
Model HR.75 / HR.75.FD	95 cm2 plus 35 cm2 per extra 2Kw or part thereof in excess of 6Kw rated heat input
Model HR.130 / HR.130.FD	95 cm2 plus 35 cm2 per extra 2Kw or part thereof in excess of 6Kw rated heat input

Typical permanent vent air requirements
	One Heater	Two Heaters	Three Heaters
Model HR.45 / HR.45.FD	235cm2 (35in2)	445cm2 (65in2)	690cm2 (102in2)
Model HR.75 / HR.75.FD	375cm2 (55in2)	750cm2 (110in2)	1125cm2 (165in2)
Model HR.130 / HR.130.FD	655cm2 (102in2)	1320cm2 (205in2)	1985cm2 (308in2)

Most proprietary building ventilation louvers are approximately only 50% free area. The above areas relate to free area and therefore most proprietary louver sizes will need to be at least doubled.

Where an overhead HEAT-RAD unit is unflued, the discharge of the combustion gases should not impinge on combustible materials, and care should also be taken to ensure that condensation does not form on cold surfaces.

FLUED INSTALLATIONS
If an HEAT-RAD overhead unit is to be flued, a down draught divertor is available from Horizon as an optional extra. The down draught divertor is designed to accept standard twin wall flue pipe.

TYPES OF FLUE INSTALLATIONS
HEAT-RAD overhead heating units may be individually flued to atmosphere. Alternatively, the Horizon Octopus flue system is available. An Octopus system allows for the individual exhaust fans on HEAT-RAD units to be deleted, and a flue system connected direct to the end of the heat emitter tube. Up to a maximum of ten heaters per system can be accommodated, the flue pipework is interconnected to a single exhaust vacuum pump to discharge the flue gases to atmosphere

Alternatively, a flue dilution system is available, flue ductwork with divertors is attached to individual HEAT-RAD units and connected by a graded system of flue ductwork to a single flue dilution fan assembly discharging to atmosphere. Systems are available to connect to any number of overhead HEAT-RAD units. An advantage with the flue dilution system is that the building is also ventilated.