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UNIT HEATER
10.3.3 Conversion of Johnson Valve to L.P.G.
For the Models 340 and 380 the valve for use on L.P.G. Propane or Butane is exactly the same Johnson
valve as for natural gas however the pressure regulator must be put out of service.
To do this for the Johnson gas valves an adaptor pipe is fitted to connect the pressure regulator
breather port to one of the valve centre test points (see Fig 10.3).
This is achieved by first removing the plastic regulator breather plug by unscrewing it and screwing in
one of the compression couplers.
Remove the centre test point that coincides with the adaptor pipe length and again replace with the
other compression coupler.
Link the two couplers with the adaptor pipe and tighten the compression fittings.
The internal regulator is now out of action and the heater must be supplied with gas closely controlled
at the correct inlet pressure of 37mbar for Propane or 29mbar for Butane.
Fig 10.3 Conversion of Johnson Gas Valve for L.P.G.
Regulator Breather Port
Pipe Link to Put
Regulator Out of Action
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