Weil-McLain WM97+ - Page 33

CWH companion water heater — Product Manual
Troubleshooting (continued)
Excessive domestic water temperature
1 Adjust WM97+ control settings and check operation.
• Follow instructions in the boiler manual and this manual to adjust tank temperature
and boiler water temperature.
• If controls are set properly, check tank sensor installation and operation.
• See the illustration at right for locations of the sensor wells. The lower well is on the
side opposite the DHW connections. (This illustration shows a right-oriented tank.)
• Check whether sensors are inserted completely into their wells. If not, press in firmly
and recheck CWH operation.
• If sensors are properly inserted in their wells, disconnect each sensor harness and
attach an ohmmeter. The table below shows the correct values for the sensor at
various temperatures.
Temp
(°F)
Sensor ohms Temp
(°F)
Sensor ohms Temp
(°F)
Sensor ohms
Min Max Min Max Min Max
32
34265 37871
90
8504 9399
150
2517 2782
40
27834 30764
100
6847 7568
160
2091 2311
50
21630 23907
110
5545 6129
170
1744 1928
60
16944 18727
120
4517 4992
180
1461 1615
70
13372 14780
130
3698 4088
190
1229 1359
80
10629 11747
140
3043 3364
200
1038 1147
• Use the resistance values at 32°F, 60°F, 70°F and 212°F to
measure the sensor resistance at known temperatures
(ice point, room temperature and sea level boiling
point). For ice point and boiling point, insert the sen-
sor in water at that temperature. Use an ohmmeter to
read resistance value. To check whether the WM97+
control is correctly sensing temperature, you can use
a resistance decade box. Connect the decade box tem-
porarily in place of a sensor and read the correspond-
ing temperature on the WM97+ control display. The
temperature should be close to the value corresponding
to the input resistance.
2 Recirculation loop needed?
• Installing a properly-sized recirculation loop will not
only provide prompt delivery of hot water, but it will
provide circulation and mixing of the water within
the tank.
3 Thermostatic mixing valve set too high?
• Follow instructions in the mixing valve manual to
check mixing valve setting temperate. Adjust if neces-
sary following the manual’s specified procedure.
4 No thermostatic mixing valve installed or mixing valve is defective?
IF THE MIXING VALVE IS NOT INSTALLED,
DISCONTINUE USE OF THE CWH AND INSTALL
THE MIXING VALVE FOLLOWING INSTRUCTIONS
IN THIS MANUAL AND THE MIXING VALVE
MANUAL.
• The CWH must not be operated without a mixing
valve installed per the instructions in this manual and
the mixing valve manual.
• Follow instructions in the mixing valve manual to
check valve operation. If valve is correctly installed and
does not operate correctly, replace the mixing valve.
Part number 635-500-156/0113
33