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7
Preparation
Check Power Supply
With multi-meter at incoming power in Hi Delta heater,
check voltage between:
Hot - Common (≈120 VAC)
Hot - Ground (≈120 VAC)
Common - Ground (< 1 VAC)
Attach Manometers to Measure Pressures
1. Turn off main gas valves.
2. Attach 24” scale manometer to the first main gas
shut-off valve pressure tapping.
3. Attach (1) 12” scale manometer to the outlet side
of the second main gas shut-off valve pressure
tapping.
4. Attach (1) 12” scale manometer near the fan-prov-
ing switch. Pull black cap from air pressure switch
tee and connect the manometer. NOTE: Retain
caps for reinstallation later.
Check Gas Supply Pressure
1. Slowly turn on main gas shut-off valve.
2. Read the gas supply pressure from the manome-
ter; minimum supply pressure for natural gas is 5.0
in. WC, recommended supply is 7.0 in. WC, mini-
mum supply pressure for propane gas is 8.0 in.
WC (dynamic readings, all stages firing).
3. If the pressure is > 14.0 in. WC, turn off the valve.
4. Check if the service regulator is installed and/or
adjust the service regulator.
FlexGas System Start-up
1. Turn off unit. Ensure that the switch on the
FlexGas control is in the position marked “NAT”.
See Fig. 6 for FlexGas control operation. Ensure
the manual valve on the natural gas supply is open
and the manual valve on the propane supply is
closed.
2. Turn on the unit, wait 15 seconds, and the igniter
should glow. Look into sight glass located at each
end of the heater to check igniter operation. Gas
valves should open in 45-60 seconds.
3. If burner does not light on first trial. It will retry, up
to three times.
4. Main burner ignition: Check manifold gas pres-
sure at gas valve outlet pressure tap. This should
read 3.5 ± 0.1 in. WC for natural gas. If the natural
gas manifold pressure is not within 3.5 ± 0.1 in.
WC, follow the instructions in the Hi Delta I&O
manual for adjusting manifold pressure. If a flue
gas analyzer is used, the CO
2
on natural gas
should be 7.5-8.5% and CO should be less than
150 ppm.
5. When acceptable operation on Natural Gas is con-
firmed, turn the gas selector key on the FlexGas
control to “OFF”.
6. Close the manual valve on the natural gas supply
then open the manual valve on the propane sup-
ply. When the heater shuts off, turn the FlexGas
control key counter-clockwise to the “PRO” posi-
tion.
7. Wait 15 seconds, and the igniter should glow. Look
into sight glass located at each end of the heater
to check igniter operation. Gas valves should open
in 45-60 seconds.
WARNING: This FlexGas heater is intended for
operation on Natural Gas as the primary fuel. DO
NOT use this heater with Propane Gas as the pri-
mary fuel.
NOTE: Do not adjust Hi Delta valve(s) or manifold
settings when operating on propane. These should
only be adjusted while firing natural gas.
WARNING: Do not turn on gas at this time.
WARNING: If Common - Ground is > 1 VAC,
STOP: Contact electrician to correct ground failure.
Failure to do this may burn out 120V-24V trans-
former, or may cause other safety control damage or
failure.
NOTE: The fan(s) pressure is already factory set to
1.4 in. ± .1 in. WC (up to 4500 ft altitude). If adjust-
ment(s) is required, consult the appropriate Hi Delta
manual.