Gas/Air Valve Setup Procedure - Potterton Powermax HE 85 Litre Installation And Servicing Instructions

PO WE -
R
+ CH
H.W .
MA INS BU RN TEM P
ON
ER
LO CK HW
OU
T
RE SE SEL
T
C.H . +
AD VAN
CE SEL
PR OG
-
PRO G
Top View
Outlet Pressure
Test Point
Inlet Pressure
Test Point
MANOMETER
P200UL
0.0 UNIT
V AUTO
HOLD
Fig. 28
42

Gas/Air Valve Setup Procedure

Fan Venturi
Air Manifold
Air Signal Signal sensing tube
Connection connected to Gas Valve
Air/Gas
Ratio Valve
Do Not use
this point
Offset
Adjustment
Throttle
Adjustment
Manometer
Condensate Vent
(Do Not disturb this vent tube)
Gas/Air Valve Setup Procedure
Procedure to correctly set new Air/Gas Valve
using a micro-manometer.
Flue Gas
Test Point
1. Loosen screw in outlet pressure test point
Air/Gas
Valve
Air
Manifold
2. Remove special ⁄ BSP screw from flue
3. Press 'ADVANCE' or central heating
4. Simultaneously press '+' and 'STEP'
Tee inserted
into signal
sensing tube
5. Ensure micro-manometer is in Pa or mbar
6. Check differential pressure reading.
Venturi
Connector
and connect to '+' (positive) side of
differential micro-manometer.
Tee the '-' (negative) side of the micro-
manometer into the air signal tube.
gas outlet (above heat exchanger) and
insert probe of combustion analyser
approximately 50 mm.
Temporarily seal probe into flue gas test
point.
'SELECT' button to obtain ON display in
programmer screen. Ensure any
connected room thermostat is calling for
heat. Observe burner lights and allow
boiler to operate in central heating mode
for several minutes.
buttons and hold down for 5 to 6 seconds.
After one minute, the boiler will be
operating at the correct reduced input rate
to enable the differential pressure to be set.
scale and has zeroed correctly. If in doubt,
re-zero the instrument.
This should be zero or a negative (gas
relative to signal) value of 0 to - 5 Pa (0.00
to - 0.05 mbar).
Use zero adjustment screw (below central
dust cover) to reset differential if
necessary.
Note: Turning adjustment screw clockwise
reduces negative differential; anti-
clockwise increases negative differential. A
4 mm hexagon key should be used to make
the adjustment.
Publication No. 5106226