79
NOTE: If switch drops-out before boiler reaches
temperature or if pressure differential readings are
below minimums shown in Table 12, check for
cracks in hose or contact your nearest Burnham
representative.
4. Stop boiler, remove manometer and reconnect hoses
to differential pressure switch. See Figures 51 and
54.
H. VS3000 / VS3001 Water Temperature Sensor Testing
Instructions
A good quality test meter capable of measuring up to
50k ohms (1k ohm = 1000 ohms) is required to measure
the sensor resistance. In addition to this, the actual
temperature must be measured with either a good
quality digital thermometer, or if a thermometer is not
available, a second sensor can be placed alongside the
one to be tested and the readings compared.
Table 12: Differential Pressure Switch Settings
Table 13: VS3000 Water Temperature Sensor - Resistance vs Temperature
First measure the temperature using the thermometer
and then measure the resistance of the sensor at the
control. The wires from the sensor must not be
connected to the control while the test is performed.
Using Table 13, estimate the temperature measured by
the sensor. The sensor and thermometer readings
should be close. If the test meter reads a very high
resistance, there may be a broken wire, a poor wiring
connection or a defective sensor. If the resistance is
very low, the wiring may be shorted, there may be
moisture in the sensor or the sensor may be defective.
To test for a defective sensor, measure the resistance
directly at the sensor location.
Do not apply voltage to a sensor at any time as
damage to the sensor may result.
Boiler Model
Minimum Differential Pressure
Sea Level to 2,000 Ft. Above 2,000 Ft. Elevation
RV3 .40” w.c. .25” w.c.
RV4 .88” w.c. .74” w.c.
RV5 .80” w.c. .65” w.c.
RV6 .80” w.c. .65” w.c.
RV7 (1” Burners) .69” w.c. .54” w.c.
RV7 (40mm Burners) .74” w.c. .59” w.c.
°F OHMS °F OHMS °F OHMS °F OHMS °F OHMS °F OHMS
50 19,900 80 9,170 110 4,730 140 2,490 170 1,390 200 838
60 15,000 90 7,400 120 3,740 150 2,010 180 1,180 210 701
70 11,900 100 5,780 130 3,100 160 1,700 190 977 220 606
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