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ELECTRICAL (SOLID STATE THERMOSTAT IID)
If the pool/spa/hot tub water is too cold, troubleshoot the system as follows:
Check voltage at 24 V terminals.
VOLTAGE BETWEEN 21.5-28.5 V.
Set control to max. temperature. After 2-3
cycles, check water temperature.
TEMPERATURE BELOW 105°F
Disconnect sensor leads from circuit board.
Measure sensor resistance with ohmmeter.
RESISTANCE 1-14k OHMS.
Check water temperature; estimate expected sensor
resistance from chart below.
MEASURED AND ESTIMATED RESISTANCE
MATCH WITHIN 20 PERCENT.
Disconnect potentiometer leads from circuit board.
Measure resistance with ohmmeter. If resistance is:
0-100 ohms at minimum setting;
9k to 11k at maximum setting,
replace circuit board.
Above 11k ohms but less than
15 k ohms, , replace potentiometer.
bove 15k ohms, fix loose or broken wires;
replace potentiometer if necessary.
Reconnect all leads and check out system.
If the pool/spa/hot tub water is too hot, troubleshoot the system as follows:
SENSOR RESISTANCE AT VARIOUS TEMPERATURES
Temperature
(deg. F) 61 68 70 77 86 88 95 104 106
Resistance (k ohms) 14.92 12.49 11.88 10.00 8.06 7.69 6.53 5.33 5.10
VOLTAGE OUTSIDE RANGE 21.5-28.5 V.
Check transformer, 120 V supply, correct as
necessary
TEMPERATURE 105-106° F.
Control ok.
RESISTANCE O OHMS (SHORT CIRCUIT)
Check system for shorted wires or open circuits.
Replace sensor if necessary.
MEASURED AND ESTIMATED RESISTANCE
DON'T MATCH.
Replace sensor. Reconnect all leads and check
out system.
Check voltage at 24 V terminals.
VOLTAGE BETWEEN 21.5-28.5 V.
Set control to max. temperature. After 2-3
cycles, check water temperature.
TEMPERATURE ABOVE 108°F
Disconnect sensor leads from circuit board.
Measure sensor resistance with ohmmeter.
RESISTANCE 1-14k OHMS.
Check water temperature; estimate expected
sensor resistance from chart below.
MEASURED AND ESTIMATED RESISTANCE
MATCH WITHIN 20 PERCENT.
Disconnect potentiometer leads from circuit board.
Measure resistance with ohmmeter. If resistance
is:
0-100 ohms at minimum setting:
9k to 11k at maximum setting,
replace circuit board.
Above 11k ohms, replace
potentiometer.
0 ohms (short circuit), replace
potentiometer.
Reconnect all leads and check out system.
VOLTAGE OUTSIDE RANGE 21.5-28.5 V.
Check transformer, 120 V supply, correct as
necessary.
TEMPERATURE 105-106° F.
Control ok.
RESISTANCE ABOVE 15k OHMS (OPEN
CIRCUIT) OR SHORT CIRCUIT.
Fix loose or broken wires. Replace sensor if
necessary.
MEASURED AND ESTIMATED RESISTANCE
DON'T MATCH.
Replace sensor. Reconnect all leads and check
out system.
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