INSTALLATION
31 BOILER ADJUSTMENTS
Fig. 31.2 Measuring the differential pressure P1
General
The Maximiser constantly controls the gas/air mixture. In
order to maintain the correct output and low emissions it is
important to have the initial adjustment correct, thus avoiding
high/low operation and/or bad emissions.
Although the boiler has been factory set, starting problems
can be caused by a variation of the gas/air pressure ratio.
The set value of the pressure difference between the gas
pressure and the air pressure should be -5 Pa (- 0.05 mbar)
at low load. A tolerance of ± 5 Pa is allowed on this value
(see fig. 31.1).
To check the setting and make any adjustments proceed as
follows.
•
Disconnect the main electricity supply.
•
Connect a hose from the -ve measuring point of the
pressure gauge to the P1+ connection of the gas/air
connection piece on the boiler. Insert a T-piece in the
hose (see fig 31.2).
•
Connect a hose from the T-piece to the ‘Dynamic
pressure from fan’ connection on the gas valve
(see frame 27).
•
Connect a hose from the +ve measuring point of the
pressure gauge to the burner pressure measuring point
on the gas valve after opening the test point with a
suitable screwdriver.
•
Remove the cover from the control panel.
•
Move the service switch to the upper position
•
Re-connect the electricity supply. The boiler will now light.
•
When the boiler is firing, press the service button for 5
seconds until the letter Y shows on the display.
•
Turn the middle potentiometer to position 1 (low load =
30% constant).
•
The Maximiser boiler will operate constantly and is now
ready to be adjusted.
Measuring the differential pressure
The differential pressure should be -5 Pa (-0.05 mbar) with a
tolerance of 5 Pa (0.05 mbar). Because of this the measured
value should be between -10 and 0 Pa.
The differential pressure can be corrected by turning the
adjustment screw of the gas pressure on the gas valve.
By turning it to the right, the differential pressure will
decrease.
Note:
The adjustment screw is protected by a star-shaped
cover on the Honeywell gas valve. This cover has to
be removed, before an adjustment can be made
(see frame 27).
The adjustment screw can be turned by means of a
Torx-bit T40H.
Use the proper tools before making an adjustment
Note:
If the hoses have been connected the opposite way
round to the gas valve or the pressure gauge,
the following abnormality will occur. By turning the
adjustment screw of the gas pressure on the gas
valve to the right, the differential pressure will increase.
After finishing the pressure measurements, the pressure
measuring nipples have to be sealed properly. Turn the
potentiometer to the desired setting. Set the test switch to
the ‘0’ position. Put the cover on the control box.
Check the disconnected gas couplings for gas leakage.
Measuring the ionization current at full load
Before the ionization current can be measured, the plug
connection in the ionization cable has to be disconnected.
Measure the ionization current in series on the contacts of
the two plugs. The ionization current should be at least 2 µA
(Fig. 31.3).
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1
2
3
4
5
6
24 VAC
24 VAC
0
- max 6 VA
7
Adjustment
screw of the
gas pressure
Fig. 31.1
turn left
-15
-10
-5
0
5 (Pa)
-0.15
-0.10
-0.05
0.00 0.05 (mbar)
turn right
Fig. 31.3 Measuring the ionization current
DC
FLUKE 73
OFF
V~
V-
300 mV
V
V
Ohm
V n
COM
459136 [Eng]
219048
Maximiser SE
- Installation
22
