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Legacy™ Model LRZM Pool/Spa Heater
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Installation and Operation Manual
11.4.5 limit switches
Since the limit switches are not easily accessible,
you can check the voltage going into the component
after the limit switches in the circuit. If voltage is
detected there, then the limit switches are closed and
are operational.
Check the voltage going to the water pressure
switch. Leave the red voltmeter lead in place at test
point 1. Touch the black lead of the meter to the termi-
nal of the water pressure switch where the black wire
is connected (test point 13).
If the voltage is less than 220mV, there may be
a bad connection, a partial short or a faulty sensor. If
there is no voltage, one of the limit switches is open.
This is normally due to excessive water tempera-
ture, which should be thoroughly investigated before
replacement of limit switches. Excessive water temper-
ature may be caused by low water flow. Water flow
deficiency may be due to obvious problems such as a
defective pump or blocked water filter. Alternatively,
excessive water temperature may be due to over-firing,
or to a problem with the water piping or the heater's
internal bypass control. Over-firing might be a result
of an incorrect gas orifice or supply of propane gas to a
heater intended for natural gas.
If there are no such fundamental problems,
identify which of the switches is open. Limit switch
access is through the limit switch plugs on the inlet/
outlet header. Remove the limit switch plugs from
the bottom of the header and gently remove the limit
switches from the wells. Move the black lead of the
meter to the terminal on the 42°C (108°F) limit switch
(test point 9) that is connected to the fireman switch
terminal block. Less than 220mV at this point means
that the wire between the terminal block and the limit
switch has a poor or broken connection or a partial
short. Replace the wire assembly. If at least 220mV is
detected at test point 9, then move the black lead of the
meter to the other terminal of the 42°C (108°F) limit
switch (test point 10). Low or no voltage here means
that the limit is open and must be replaced.
If 220mV or more is detected at test point 10,
move the black lead of the meter to the terminal on
the 52°C (126°F) limit switch (test point 11) that is
connected to the 42°C (108°F) limit switch. Less than
220mV at this point means that the wire between the
two limit switches has a poor or broken connection
or a partial short. Replace the wire assembly. If at
least 220mV is detected at test point 11, then move
the black lead of the meter to the other terminal of the
52°C (126°F) limit switch (test point 12). Low or no
voltage here means that the limit switch is open and
must be replaced. If voltage is detected at test point 12,
move the black lead of the meter to the terminal of the
water pressure switch where the black wire from the
high limits is connected (test point 13).
Less than 220mV at this point indicates that the
wire connecting the high limits to the water pressure
switch is faulty or poorly connected. Correct the
problem or replace the wire.
note
The limit switches have different trip points,
and it is important that replacements are
correct. The 42°C (108°F) switch has a red
dot on the top of the switch, and must be
installed in the inlet side of the header. The
52°C (126°F) switch has no dot and must be
installed in the outlet side of the header in the
well farthest from the heater jacket.
11.4.6 Water pressure switch
If the meter shows at least a 220mV signal at test
point 11, move the black lead of the meter to the other
terminal on the water pressure switch (test point 14).
If there is no voltage, the pressure switch contacts
are open. This is almost always due to a water flow
deficiency, the most common one being a blocked water
filter or defective pump. However, sometimes it is due
to blockage of the copper tube or mis-adjustment of
the switch. Investigate thoroughly, referring to Section
11.5 “Adjusting the Water Pressure Switch”. If there
is no problem with the pool system or pressure switch
adjustment, replace the pressure switch.
11.4.7 temperature Control Circuit
The temperature control circuit consists of two
(2) major components which must all be working
correctly for the signal to be transmitted to the gas
valve. The components are the ON/OFF toggle switch
and the mechanical thermostat. Use the following
procedure to check each component for functionality.
Check the temperature control as a complete
circuit before checking each component individually.
With the red lead of the meter still at test point 1, place
the black lead of the meter on the back of the mechani-
cal thermostat (test point 16). If the meter shows more
than 220mV at the pressure switch (test point 14) but
not at test point 16, then one of the components of the
temperature control circuit is faulty. Proceed with the
following sections to test the components.
11.4.7.1 on/oFF toggle switch
Remove the temperature control panel from the
bezel on the front of the heater to gain access to the
switch. Be sure that the toggle switch is in the "ON"
position. Place the black lead of the meter on the
toggle switch terminal (test point 15) that is connected
to the pressure switch. Less than 220mV at this point
indicates that there is a problem with the black wire
that connects the pressure switch to the toggle switch.
If at least 220mV is detected at test point 15, move the
black meter lead to the other terminal on the toggle
switch (test point 16).
Summary of Contents for Legacy LRZ
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