Preparation; Start-Up - Rheem Raypak MVB 503A Installation And Operation Manual

Preparation

WARNING: Do not turn on gas at this time.
A
Check Power Supply
With multi-meter at incoming power, 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 valve.
2. Attach (1) 12" scale manometer to an upstream
bleedle valve on the gas supply pipe to the heater.
Measure point "A" in Figure 41.
3. Attach (1) 12" scale manometer near the fan proving
switch. Pull black cap from air pressure tee as shown
in Figure 42 and connect the manometer. NOTE:
Retain caps for reinstallation later.
GAS B
A
Figure 41. Gas Pressure Measurement Locations
Check Gas Supply Pressure
1. Slowly turn on main gas shutoff valve.
2. Read the gas supply pressure from the manometer;
minimum supply pressure for natural gas is 4.0 in.
WC, recommended supply is 7.0 in. WC, minimum
supply pressure for propane gas is 4.0 in. WC,
recommended supply is 11.0 in. WC (dynamic
readings, full fire input).
3. If the gas pressure is greater than 14.0 in. WC,
turn off the main gas shutoff valve, upstream of the
heater.
42
TO BURNER
C
F10675

Start-Up

NOTE: Technician performing initial start-up must carry
a calibrated combustion analyzer to ensure desired
combustion levels are achieved.
NOTE: The values in Table R represent the conditions
when the heater is at full firing rate at sea level.
NOTE: Pressure and combustion data are provided with
the heater.
1. Turn power on.
2. Turn on the heater, wait approximately 15 seconds
after the blower starts, the igniter should start to glow
(observable through the observation port located at
the front, below the gas valve). Look into the sight
glass located just below the gas valve near the front
of the unit to check igniter operation. Gas valve
should open in 45-60 seconds.
3. The heater ignites at 30% to 50% of full rate
(as indicated on the touchscreen display of the
temperature controller located behind the front
panel).
4. If the burner fails to light on the first 4-sec trial for
ignition, it will try for ignition up to three times before
going into lockout with the standard ignition module.
If the heater is equipped with the optional single-try
ignition module, it will go into lockout after the first
failure to light.
5. Wait until the controller indicates 100% on the firing
rate display screen (approximately 30 seconds).
Figure 42. Air Pressure Tee
MANIFOLD TAP
AIR PRESSURE
TEE
MODELS 503A-1503A SHOWN