Rheem 27 874 Series - Burner Gas Pressure Checks

COMMISSIONING
67
BURNER GAS PRESSURE
It is necessary to check the burner gas pressure at both the minimum and maximum operational settings. To
check and if necessary adjust the operational gas pressures, the electrical supply to the water heater must
be switched on, the burners ignited and hot water must be flowing from a hot tap.
Warning: The removal of the front panel will expose 240 volt wiring. Take care not to touch wiring
terminals.
Minimum test point gas pressure
Refer to the rating label on the water heater for the minimum test point gas pressure.
1. Close any hot taps and ensure the burners are not
operating.
2. Turn off the controller(s), if one is fitted, by pressing the
on / off button and switch off the electrical supply at the
power outlet to the water heater.
3. Remove the screws holding the front panel to the jacket.
4. Gently disengage the front panel and pull forward to
remove from the water heater.
5. Locate the burner pressure test point on the main burner
manifold.
 Remove the test point screw and washer from the
test point orifice.
 Connect the manometer.
6. Switch on the electrical supply at the power outlet to the
water heater and turn on a controller, if one is fitted, by
pressing the on / off button.
7. Open the gas isolation valve fully at the gas inlet to the
water heater, if not already open.
8. Open a hot tap slowly until the burners ignite.
9. Press and hold down the MIN button and observe the
reading on the manometer.
 “1L” is shown on the LED display.
10. Release the MIN button.
If the manometer reading observed in step 9 agrees with
the rating label, no further adjustment is required.
11. To adjust, press and hold the adjuster button.
 “LH” is shown on the LED display.
Note:
The adjuster button must be held down
continuously through steps 11 to 13.
12. Press and hold the MIN button and observe the reading
on the manometer.
 The manometer reading will change as the test point
gas pressure adjusts.
Note: While the MIN button is pressed, the gas pressure will at first increase then decrease, cycling
between an upper gas pressure limit (39 on the LED display) and a lower gas pressure limit (01 on the
LED display).
13. Release the MIN button when the reading on the manometer agrees with the rating label.
14. Release the adjuster button.
TEST
POINT
SCREW
WASHER
TEST POINT
ORIFICE
MANOMETER
MIN. BUTTON
MAX. BUTTON
ADJUSTER
BUTTON
DIP 1 SET OF
DIP SWITCHES
1234
OFF ON
DIP1
1234
ON
1234
OFF ON
DIP2
MIN MAX ADJ
1234
ON