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From PRO to NAT:
1. Turn the boiler off (power switch on front control
panel).
2. Turn FlexGas key to “OFF”.
3. Close PRO manual valve.
4. Open NAT manual valve.
5. Turn FlexGas key to “NAT”.
6. Turn the boiler on.
Safety Inspection
1. Check all thermostats and high limit settings.
2. During the following safety checks leave ma-
nometers hooked up, check and record.0
3. If other gas-fired appliances in the room are on the
same gas main, check all pressures on the Hi
Delta with all other equipment running.
4. Check thermostats for ON-OFF operation.
5. Check high limits for ON-OFF operation.
6. While in operation, check flow switch operation.
7. Check the low gas pressure switch. (For proper
adjustment, use the attached manometers, if
available, to set pressure. The scales on the
switch are approximate only.) Low gas pressure
switch (if equipped) must be set at 5.0 in. WC for
natural gas.
Follow-Up
Safety checks must be recorded as performed.
Turn heater on. After main burner ignition:
1. Check manometer for proper reading.
2. Cycle heater several times and re-check readings.
3. Turn unit off.
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8. If burner does not light on first trial. It will retry, up
to three times.
9. Main burner ignition: Check upper manifold gas
pressure.
10. If the pressure readings differ by more than ± 0.1
in. WC, remove screw cover from the gas pres-
sure regulator on the FlexGas fuel train and adjust
until upper manifold pressure is nominally 2.2 ±
0.1 in. WC (manifold pressure 1.3 ± 0.1 in. WC). If
a flue gas analyzer is used, the CO
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on propane
should be 9.0-10.0% and CO should be less than
150 ppm.
11. Replace the screw cover.
12. Turn the gas selector key on the FlexGas control
panel to “OFF”.
13. Close the manual valve on the propane gas supply
and open the manual valve on the natural gas
supply. Turn the gas selector key on the FlexGas
control clockwise to “NAT”. The heater is now
ready for operation.
FlexGas Operation - Changing Fuels
From NAT to PRO:
1. Turn the boiler off (power switch on front control
panel).
2. Turn FlexGas key to “OFF”.
3. Close NAT manual valve.
4. Open PRO manual valve.
5. Turn FlexGas key to “PRO”.
6. Turn the boiler on.
NOTE: Reset Low Gas Pressure Switch (when
equipped) if necessary. Refer to Fig. 2 for location.
CAUTION: Special manifold and air settings may
be required. Verify rating plate and blower housing.
CAUTION: Once the natural gas pressures are
established, DO NOT adjust the Hi Delta gas valves
to attain the required propane pressures.
Adjustments must be made to the FlexGas propane
regulator.