Lochinvar MP2 - Manual (Page 20)

A good quality electrical test meter, capable of reading from
at least 0 - 300 V (ac) and at least 0 - 2,000,000 ohm, is
essential to properly test the wiring and sensors.
ƽ
T EST T HE S ENSORS
In order to test the sensors, the actual temperature at each
sensor location must be measured. A good quality digital
thermometer with a surface temperature probe is recom-
mended for ease of use and accuracy (FIG. 33). Where a
digital thermometer is not available, a spare sensor can be
strapped alongside the one to be tested and the readings
compared. Test the sensors according to the instructions in
INS7141.
T EST T HE P OWER S UPPLY
Make sure exposed wires and bare terminals are not in con-
tact with other wires or grounded surfaces. Turn on the
power and measure the voltage between the Power L and
Power N terminals (10 and 9) (FIG. 34) using an AC volt-
meter, the reading should be between 103.5 and
126.5 V (ac).
ƽ
T EST THE P OWERED I NPUTS
Boiler Demand
If a boiler demand is used, measure the voltage between
the Boil Dem and the Com Dem terminals (6 and 7)
(FIG. 35). When the boiler demand device calls for heat,
you should measure between 20 and 260 V (ac) at the ter-
minals. When the boiler demand device is off, you should
measure less than 5 V (ac).
DHW Demand
If a DHW demand is used, measure the voltage between
the Setp / DHW and the Com Dem terminals (8 and 7)
(FIG. 35). When the DHW demand device calls for heat, a
voltage between 20 and 260 V (ac) should be measured at
the terminals. When the DHW demand device is off, less
than 5 V (ac) should be measured.
Set Point Demand
If a set point demand is used, measure the voltage between
the Setp / DHW and the Com Dem terminals (8 and 7) (FIG.
35). When the set point demand device calls for heat, you
should measure between 20 and 260 V (ac) at the termi-
nals. When the set point demand device is off, you should
measure less than 5 V (ac).
External Input
If an external input is used, measure the voltage between
the Com - and the Out + terminals (1 and 4). When the
external input device calls for heat, you should measure
between 0 and 10 V (dc) at the terminals.
FIG. 33
10 9
Power
L N
103.5 to 126.5 V (ac)
V
FIG. 34
20
FIG. 35
FIG. 36