Figure 89
Forced Low
Switch No.
F
O
F
8
5
7
6
4
3
ON
1
2
Figure 90
Forced High
Switch No.
F
O
F
8
5
7
6
4
3
ON
1
2
Figure 91
Normal
Switch No.
F
O
F
8
5
7
6
4
3
ON
1
2
Figure 88
Access plug
B. Turn on the gas supply.
C. Turn on the power supply.
D. Flow water through the water heater at the
maximum flow rate obtainable. (At least 3
gallons per minute is recommended.)
E. Move No. 7 dip switch of the SW1 bank to the
ON position to calibrate “Forced Low”
combustion. (Figure 89)
F. Check the burner test point pressure.
G. Remove the rubber access plug (Figure 88) and
adjust the regulator screw on the modulating
valve to obtain the correct low fire manifold
pressure. Refer to the data plate on the unit.
Install rubber access plug.
H. Move No. 7 and No. 8 dip switches of the SW1
bank to the ON position to calibrate “Forced
High” combustion. (Figure 90)
I. Check the burner test point pressure.
J. Adjust the high pressure Potentiometer (POT)
(Figure 86 or 87) on the PC Board to obtain the
correct high fire manifold pressure. Refer to the
data plate on the unit.
K. Move No. 7 and No. 8 back to the OFF position
to return the appliance to “Normal” combustion.
(Figure 91)
L. Close hot water taps.
M. Turn off gas supply and 120 V power supply.
N. Remove manometer and re-install allen head
plug.
O. Turn on the gas supply and 120 V power
supply.
P. Operate the unit and check for gas leaks.
3. Install the front panel using four screws.
Gas Pressure Setting Procedure
On-Demand Gas Tankless Water Heater Service Manual
56
