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Hi-E2
"Adjustment of Pressure Switch". If there is no problem
with the pool system or pressure switch adjustment,
replace the pressure switch.
4E-2f. Temperature Control
Probe for voltage at point 6, which is the terminal
of the venturi pressure switch having a yellow & black
wire connected to it. This is the switch mounted on the
frame above the blower between the vent diffuser and
the venturi tailpipe. It is about 4" in diameter.
Absence of voltage at point 6 indicates that the
Flex Temp control is not calling for heat. Be sure that
knobs are set to call for heat as in di cat ed earlier and
as described in the Op er at ing Instructions section of
this manual. Verify that the thermistor sensor wires are
not severed or shorted. Check wiring con nec tions by
removing the temperature control through the front of
the bezel. If the control is properly set and all wiring
and connections are correct, replace the Flex Temp
control.
4E-2g. Venturi Pressure Switch
Touch the voltmeter probe to point 7, which is
the terminal of the venturi pressure switch having a
purple wire connected to it. If there is no voltage at
point 7, the venturi pressure switch is open, indicating
inadequate fl ow through the combustion system.
The venturi pressure switch is a differential type
switch which is activated by the pressure difference
created when air fl ows through the venturi. When
the combustion blower is not operating, the venturi
pressure switch must be open and voltage will not be
present. See following sections on ignition control
"lockout" and combustion blower operation for
possible remedies.
Check for blockage at the combustion air inlet, a
dirty air fi lter or blockage at the vent exhaust or in the
vent. In improperly installed vent may trap condensate
water, for ex am ple, restricting fl ow. If there is no
obvious problem, analyze venturi operation as out lined
in a later section of this manual. If fl ow is normal,
replace the Venturi pressure switch.
4E-2h. Ignition Control
There will be voltage at point 8, which is the
"MVP" terminal of the ignition control, only when
there is an attempt to ignite the burner or when the
ignition control's fl ame sensing system has determined
that it is OK to allow burner operation. Even if voltage
has been confi rmed at point 7, the "trial for ignition"
sequence is imposed by the ignition control. This
sequence consists of a 15 second period of pre-purge
blower operation, a 20 second period for heatup of the
igniter and a 7 second trial for ignition, during which
there is voltage at point 8. If satisfactory ignition is
not achieved, the igniter is turned off and the blower
is operated for a 45 second post-purge. The system
may go through this cycle as many as three times, but
thereafter it is "locked out" by the ignition control.
Additional attempts will be made only if the call for
heat is interrupted by turning off electrical power or
setting the Flex Temp control to "Off".
To trouble shoot the ignition control, connect
the voltmeter probe at point 8 and set the Flex Temp
control to call for heat. Observe that the normal
sequence takes place by noting blower operation,
the glow of the igniter through the combustion
chamber sight glass and then voltage at point 8. If the
blower does not operate or the igniter doesn't glow,
investigate as outlined in a later sec tions. If both of
these components operate normally but voltage doesn't
appear at point 8 during the trial for ignition, replace
the ignition control. If voltage appears at point 8
but there is no ignition, proceed to analysis of other
components.
4E-2i. Burner Limit Switch
The burner limit switch is located on the front
surface of the burner plenum near the top of the heater.
Servicing this switch normally requires removal of
the top of the heater, but it can be checked by probing
for voltage at point 9 on the vent limit switch. Point
9 is the terminal of the vent limit switch to which is
connected a brown wire coming down from above.
The vent limit switch is mounted on the vent outlet
diffuser above the combustion blower.
Voltage will be present at point 9 only during
normal operation or during a trial for ignition. If
necessary restart the heater using the Flex Temp
control to obtain one of these con di tions. If voltage
does not appear at point 9, the burner limit switch
is open. This may be due to burner mis-adjustment,
incorrect gas orifi ce size or similar problems which
should be investigated as outlined in later sections. If
there are no such problems and there is no evidence of
excessive burner temperature, replace the burner limit
switch.
4E-2j. Vent Limit Switch
Probe for voltage at point 10, which is the gas
valve terminal having a brown wire con nect ed to it. As
in the preceding case, this terminal will have voltage
present only during a trial for ignition or during
normal operation. If voltage is not found, the vent limit
switch is open, indicating that the exhaust temperature
has been too high.
Normal vent temperature is between 100
and 140
o
F. Excessive temperature might be due to
excessive water temperature or overfi ring of the
system. Investigate water temperature and possible
water fl ow de fi cien cy. Confi rm that the heater
is equipped for the correct fuel gas - especially
that pro pane gas is not being provided to a heater
confi gured for natural gas. To confi rm cor rec tion of the
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o
F
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