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UNIT HEATER
3.3 Gas Supply
General
The installation must comply with local laws and regulations, and the complete installation including
the meter where fitted, must be purged and tested for soundness.
The gas supply must be via metal pipes and terminate at the heater with a service gas cock and union
as in Fig. 3.1 to facilitate servicing.
The gas supply pipes must be sized to supply the correct amount of gas to the heater at the specified
inlet pressure under all load conditions.
It will generally be required to use installation pipes of a larger diameter than the heater inlet connection.
On suspended heaters it is recommended that an approved metal flexible connection is used between
the service cock and the heater.
Note: Due to the design of flexible connectors it is usually needed to use at least one pipe size larger
than the supply gas pipe to reduce the pressure loss through the connector.
Natural Gas
The gas meter and service must be checked by the local gas supply undertaking to ensure that it is
adequate to deal with the total connected load of the completed installation.
L.P.G.
For L.P.G. applications each heater must be provided with gas with the inlet pressure closely controlled
to 37 mbar for Propane (G31) or 29 mbar for Butane (G30). This is best provided by the installation of
a suitable regulator controlling the inlet to each heater to ensure that variations in system pressure are
not transferred to the individual heaters.
3.4 Flue
Each heater must be fitted with at least one metre of an individual and correctly sized stainless steel
flue (see Section 2 Tables) .which is designed to carry the products of combustion outside of the
building in accordance with B.S. 6230 or B.S.5440 Part 1 as appropriate.
Suitable flue may be supplied by Combat Engineering Ltd.
A separate draught diverter is not required as the heaters have one built in. No other appliance may be
connected to the flue.
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