摘要 |
An external circuit that works in conjunction with the existing tank thermostatic controls to control both a heat pump and existing resistance elements in compliance with existing governmental codes. At the same time, this circuit disables the resistive heating elements in the hot water tank and enables the heat pump connected thereto so that the heat pump heats the water in the hot water tank. The control of the operation of the heat pump is provided through the thermostat(s) in the existing tank circuitry in the hot water tank which normally controls the resistive heating elements. At the same time, the electric resistive heating elements remain available for standby use. Further, the circuitry of the invention precludes the simultaneous operation of the electric resistive heating elements in the hot water tank and the heat pump heating unit.
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