Lochinvar GAS HEATER FOR COMMERICAL POOL Installation And Service Manual page 53

Installation and Service Manual
PREPURGE
(Ignition Module Function)
Once the ignition module sees a 24VAC input from its pressure
switch, it runs the blowers for approximately 15 seconds in
order to purge the combustion chamber of any unburned
fuel/air mixture.
IGNITER WARM-UP AND PROVING
(Ignition Module Function)
Once the ignition module has completed its prepurge period, it
turns on the hot surface igniter. Once the hot surface igniter's
current draw reaches a proper level, the ignition module begins
an additional period of approximately 25 seconds for the
igniter to ensure the ignition temperature is attained to ignite
the fuel/air mixture.
IGNITER
(Controlled by Ignition Module)
One igniter is provided in order to ignite the fuel/air mixture
and its operation and timings are controlled by the ignition
module.
IGNITION AND FLAME PROVING
(Ignition Module Function)
Once the warm-up and proving period has been completed, the
ignition module sends 24VAC to the gas valves on
approximately half of the pool heater. These gas valves should
open and allow gas to flow to the burners. The fuel/air mixture
should ignite from the hot surface igniter. Once this voltage
has been sent to the valves, the hot surface igniter is turned
"OFF". The ignition module then monitors and proves the
presence of the flame and will either allow operation to
continue or shut down the gas valves should flame not be
proven and proceed to a Flame Failure condition. If flame was
proven briefly during the ignition period, the module may not
proceed to Flame Failure, but rather post-purge and then go
into another trial for ignition.
SOFT-START
MODELS 990,000 - 2,070,000 BTU/HR ONLY
(Controlled by Temperature Controller)
A small time delay is provided to delay the opening of
approximately half of the valves until the first half of the
valves have opened and the gas has successfully ignited and
established flame on the burners.
HEAT TRANSFER PROCESS
(Gas Valves, Burner and Heat Exchanger)
Once flame has been proven, the ignition module will hold the
gas valves open as long as there is proof of flame and a call for
heat is present. When the temperature of the water reaches that
of the programmed set point, the pool heater will be shut down.
POST-PURGE
(Ignition Module Function)
When 24VAC is removed from the ignition module's
thermostat input, the module turns "OFF" the gas valves and
maintains the blowers for approximately 25 seconds in order to
allow the combustion chamber to be purged of all combustion
by-products.
IDLE
(Temperature Controller Function)
After completion of the post-purge cycle, the pool heater will
go into an idle state whereby the temperature controller
continuously monitors the water temperature until the water
temperature drops to levels that require additional heat.
53