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MSEV Series and USHX Hardware Installation Manual Rev 1.7
an over-voltage. If a 24V MSEV series valve is powered by a 12V power source, the
valve will not fully open due to an under-voltage.
2.
Obtain a Class 2 24 VAC transformer with a capacity of 40 to 100 VA and an output of 24 VAC at a
frequency of 60 Hz. Alternatively, a 120 VAC to 12 VDC or 120 VAC to 24 VDC Class 2 step-down
power supply with a 40 to 100 W power rating may be used. The schematics of the power sources
are shown below in Figure 3-4. See Table 3-1 below to determine what minimum capacity/power
rating requirements must be met with these power sources based on the number of MSEV series
valves installed.
For the user’s own safety, only Class 2 power sources should be used to power the
MSEV series valves and USHX devices.
Figure 3-4 Class 2 AC and DC power sources
Table 3-1: AC Transformer Minimum Capacity and DC Power Supply Minimum Power Rating Required
Based on Number of MSEV series valves Installed
MSEV Series
Valve
Voltage
Type
Number of MSEV
series valves per
Power Source
(Maximum 6)
AC Transformer
Minimum Capacity
Required (Volt-Amps)
DC Power Supply
Minimum Power Rating
Required (Watts)
12V or 24V
1
40 VA
40 W
2
50 VA
50 W
3
60 VA
60 W
4
70 VA
70 W
5
80 VA
80 W
6
100 VA
100 W
