Fan Pressure Test; Setting The Boiler To Maximum; Fan Pressure - Worcester 27Ri Compact Installation, Commissioning And Servicing Instructions

6.5

FAN PRESSURE TEST

This test is to determine if the heat cell requires cleaning
or attention.
Before setting the boiler to maximum output for the fan pressure test,
refer to figure 66:
▶ Switch the boiler off.
▶ Remove the combustion air intake pipe (1).
▶ Remove the fan pressure test point cover (2).
▶ Connect the digital manometer pipe (3) to the fan pressure test point
(4).
▶ Replace the combustion air intake pipe.
▶ Switch the boiler on.
▶ Set the boiler to maximum output.

6.5.1 SETTING THE BOILER TO MAXIMUM

To set the boiler to maximum output:
▶ With the Control panel in the service position, press the Service mode
button (1) for more than five seconds.
– The red L.E.D. (2) will flash.
– Turn the control knob to "max" and boiler will go to maximum
output, the red L.E.D. will give a five flash sequence.
▶ Turn the central heating control to maximum to ensure that the fan/
gas valve do not modulate.
1
2
Fig. 65 Setting boiler to maximum
Greenstar Ri Compact 6 720 646 610 (2013/12)
≈
5 s 5 s
min
max

6.5.2 FAN PRESSURE

1
4
3
2
Fig. 66 Fan pressure test point
NOTICE: Fan pressure test
▶ The boiler must be run at maximum output for the fan
pressure test and flue gas analysis.
With the combustion air intake pipe fitted and the boiler running at
maximum output, measure the fan pressure:
▶ The pressure will read negative, refer to the chart in figure 67 below.
FAN PRESSURE TEST
Clean the Heat Ex.
NG Boilers
27Ri: -3.3
30Ri: -3.8
0 -1 -2 -3
LPG Boilers
27Ri:
-3.3
30Ri:
-3.8
0 -1 -2 -3
Fig. 67 Fan pressure readings
▶ If the manometer reading is in the white area of the chart the heat
exchanger/exhaust path/siphon does not require attention.
▶ If the manometer reading is in the black area of the chart then carry
out the following checks:
– Check that the siphon is not blocked.
– Check the exhaust paths for restrictions.
– Clean the heat exchanger with a suitable cleaning tool, refer to
section 6.7 - Cleaning the heat exchanger.
▶ Re-check the fan pressure readings.
If the boiler, after completing the above checks, fails the fan pressure
test then contact Worcester, Bosch Group for advice.
▶ After the measurements are taken switch the boiler off.
▶ Remove the combustion air intake pipe.
▶ Disconnect the manometer and replace the test point cover.
▶ Replace the combustion air intake pipe.
SERVICE AND SPARES
Heat Ex. ok
-4 -5 -6 -7 -8
mbar
-4 -5 -6
-7 -8
mbar
35