A.O. Smith TC-049R3 Service Handbook page 47

RESIDENTIAL GAS AND ELECTRIC WATER HEATER
SERVICE HANDBOOK
Residential Electric – continued
Testing The A-7 Wiring Circuit
A-7 Circuit:
Two elements
Two thermostats
Two high limits
Four wires
Non-simultaneous operation or simultaneous
Prior To 1996 Post 1995
Supply wiring may be a: (See Pages 34 and 37)
1. three wire, 3 phase circuit:
2. two wire, single phase circuit or
3. connection to an off peak meter or time clock.
This third, wiring system interrupts power to the lower thermostat during the designated
time period but does not interrupt power to the upper thermostat.
If the consumer uses enough of the stored hot water to drop tank temperature at the top
of the tank to call for upper element activation, then the upper element will reheat the
upper third of the tank
A.O. Smith Water Products Company Technical Training Department
46
Ashland City, TN
©2005