Laars Mighty Max VW Series, Installation, Operation And Maintenance Instructions

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Mighty Max Volume Water Heater
Page 17
3. Normal Operating Sequence
When the circulation pump is running, the heater
will turn itself on and off in response to the
water temperature. When the water cools below
the set temperature, the following sequence
occurs:
a. The aquastat powers the ignition control.
b. The ignition control turns on the
combustion fan. After about a 15 second
pre-ignition purge, while the fan clears the
combustion chamber, the igniter is turned
on. The igniter takes about 25 seconds to
heat up. You can see a glow through the
view port (see Figure 12).
NOTE: The manual gas valve must be ON for
the burner to ignite. This valve is turned ON as
follows:
• Size 775/1000 Valve is ON when handle is
parallel to as pipe.
• Sizes 320/400 Turn counterclockwise
520/625 to ON.
c. When the igniter is hot, the ignition control
turns on the gas valve and the burner
ignites. You can see the burner flame
through the view port (see Figure 12).
d. The heater operates until the aquastat
senses that the water is hot enough, and the
burner shuts off. The combustion fan runs
for about one minute to blow all
combustion products out of the boiler.
If the igniter fails to ignite the burner in step 3
(for example, if there is air in the gas line), the
ignition control shuts off the gas valve after a few
seconds of operation. The purge and ignition sequence
is automatically repeated. If there is no ignition in
three tries, the ignition control “locks out” until the
problem is corrected. Contact a qualified service
technician.
3B. Hi-Limit Checkout
After running the boiler for a long enough period
to bring the water temperature within the range of the
hi-limit, slowly back off the high limit setting until the
boiler shuts off. The main burners should re-ignite
when the hi-limit is turned back up to its original
setting and the hi-limit is reset.
3C. Venturi and Gas Pressure Regulator
System
3C-1. Overall Operation
The gas control system of the Mighty Max
heater is similar to that of a carburetor of a gasoline
SECTION 3.
Operation
WARNING
Do not use this appliance if any part has been under
water. Immediately call a qualified service technician
to replace the appliance.
3A. Start Up Requirements
Lighting: Safe lighting and other performance
criteria were met with the gas manifold and control
assembly provided on the boiler when it underwent
tests specified in ANSI Z21.10.3 Standard.
Before placing the heater in operation, check the
automatic safety shutoff devices. Once the heater is
connected to the gas piping and after all of the
requirements in Section 2 have been met, follow this
procedure:
1.
Before beginning the tests, make sure the main
manual gas valve, and any other boiler firing
valves, are in the OFF position.
NOTE: The gas valve is turned off as follows:
•
Size 775/1000 Valve is OFF when handle
is at right angle to gas pipe.
• Sizes 520/625 Turn clockwise to OFF and
• Sizes 320/400 Press in gas control knob
slightly and turn clockwise to
OFF. Knob cannot be turned
unless it is pushed in slightly.
Do not force it.
2. Make sure the power switch on the heater is in
the ON position. Reset all safety devices (high
limit, pressure switch, Low-Water-Cutoff, etc.).
Figure 12. Periodic Flame Observation.
Junction
Box
Front View of Boiler
NOTE: Sight glass
location may vary.
Igniter
Sight Glass
For Flame Observation