Figure A6 Lpg Orifice Fitted; Figure A7 Alternative Lpg Orifice - Hamworthy MILBORNE381 Series Design Installation, Commissioning And Operating Instructions

6. The LPG orifice consists of a precisely drilled
washer of 6.5mm internal diameter. This orifice is to
be fitted in the gas valve outlet port. There is no need
to remove the rubber seal to complete this operation.
7. Figure A6 shows LPG gas orifice correctly located
in the gas valve air inlet passage.
Figure A6
NOTE: In certain circumstances it is necessary to
fit a larger LPG orifice to the gas valve air inlet
port. If poor ignition
commissioning the boiler then the larger orifice
may be fitted. It is important to commission the
boiler first, as correctly setting the gas valve
offset for clean combustion may overcome initial
poor ignition.
The alternative LPG orifice is sized at 6.75mm internal
diameter and is fitted in exactly the same way as the
6.5mm diameter orifice. If fitting the larger orifice then
the 6.5mm diameter orifice must first be removed.
Parameter Description
36 Type of Gas
HAMWORTHY HEATING LTD
is experienced after
Range Default
1-24 1
MILBORNE
Figure A7
8. To replace the assembly, ensure that all the
components that have been removed and modified
are clean. Position the venturi to the gas valve and
refit 3 screws that were previously removed in step 4.
Ensure the 3 screws are securely tightened to prevent
leaks at the venturi to gas valve joint.
9. Modifying the Boiler Parameter, Master Boiler Only
It is essential to modify the boiler parameter
number 36 to identfy the type of gas being used. This
must also take account of the flue length as indicated
in the table below. To modify the parameter it is
necessary to reinstate the gas and electrical supplies.
WARNING! As the boiler MUST NOT fire before the
parameter is modified ensure that there is no
demand for heat from any of the connected
circuits and time clock controls.
Notes:
1. The procedure for modification and adjustment of
the parameters at the Master Control Panel is detailed
in Section 8.5 of this manual.
2. Once the boiler has been modified for LPG firing it
is essential to complete the full commissioning
procedure to all boiler modules as detailed in Section
7.0
3. If after commissioning, the larger orifice has to be
installed then the full commissioning procedure as
detailed in Section 7.0 must again be completed.
501/502 boilers
1= Natural Gas with equivalent flue length < 15m
2= Natural Gas with equivalent flue length > 15m
3= LPG with equivalent flue length < 15m
4= LPG with equivalent flue length > 15m
381/382 boilers
21= Natural Gas with equivalent flue length < 15m
22= Natural Gas with equivalent flue length > 15m
23= LPG with equivalent flue length < 15m
24= LPG with equivalent flue length > 15m
57
Specification
500001130/J