Technical data

© MHS Boilers Ltd
221106 Draft Copy E&OE
35
This mode is maintained until the limit thermostat temperature is reached or the
Chimney Sweep or P Button is pressed from more than 1 second. The module stops
operating when the button is released.
Whilst the module is operating under the control of the Chimney Sweep Button (with
adjustment) the gas valve can be adjusted to give correct flue gas analysis readings.
Each module is equipped with a modulating gas valve.
The modulating gas valve must be set at High Fire and Low Fire to ensure correct
operation throughout its modulating range.
It is advisable to check the combustion figures on High and Low Fire prior to carrying
out any adjustments.
Adjusting the High Fire has a marked effect on the Low Fire figures.
Where as adjusting the Low Fire has little effect on the High Fire figures.
The High fire adjustment is carried out via the 2.5mm Allen Key socket D
The High Fire adjustment is a Gate type restrictor.
Therefore turning the screw clockwise will close the gate and thus restrict the quantity
of gas passing through to the burner.
The Low fire adjustment is carried out via the 2.5mm Allen Key socket N
The Low Fire adjustment is a diaphragm governor.
Therefore turning the screw clockwise will increase the pressure on the diaphragm and
thus increase the quantity of gas passing through to the burner.
Legend
A. Valve Inlet Gas Pressure Test Point
B. Valve Outlet Gas Pressure Test Point
D. High Fire Adjuster (Gate Type)
N. Low Fire Adjuster (Governor Type)
Each module must be analysed and adjusted separately.
This is undertaken by inserting the analysers probe in to the silicone sampling tube
secured to the top of each module and sealed with a black plug. If fluctuating figures
are obtained the flue gas analyser should be inserted directly into the module flue
spigot once the silicone tube has been temporally removed.
Each module must be set to the following combustion figures.
Gas Type Injector Size High Fire Low Fire
Natural Gas (G20) 15mm (Exploded Part #79) 8.5% C0
2
9.0% CO
2
LPG (G31) 10mm (Exploded Part #79) 11.0% CO
2
11.0% CO
2