Service & TroubleshootingCâu 78 / 110
A typical low-voltage control (thermostat) circuit in residential HVAC operates at what voltage?
a.120 volts
b.240 volts
c.24 volts
d.480 volts
Giải thích
Residential control circuits generally operate at 24 volts AC, supplied by a step-down transformer. The thermostat switches this low voltage to energize relays and contactors. Measuring 24 volts at the appropriate terminals helps confirm control-circuit operation.
Luyện miễn phí toàn bộ 110 câu hỏi — không cần đăng ký.
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