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INSTALLATIONCONSIDERATIONS

Models

Thereare four models in the Legacy Series: programmable and non--programmable,AC
and HP. Models T2--PACan d T2--NACa re designed for AC systems, co ntrolling one
stage of cooling and one stage ofheating. They will not operate a heat pump.Models
T2--PHP and T2--NHPare de signed for HP systems, controlling two stages of coolin g
and three stages of heating. They can be converted to AC operation. Select the
appropriatemodel for the intended application.

Power

All Legacy Series models are dual powered. They can operate from batteries or
24VACpo wer.Op eration from 24VAC is preferred if availab le. Battery operation is
used when there are not enough wires to support 24VAC operation or when
“armchair programming”is desired. For an AC system, up to six wires are needed
for24VAC operationand one less wire for battery operation.For a HP system, up to
seven wires are needed for 2 4VACopera tion and and one less wire is sufficientfor
battery operation. For h eat only operation with ba tteries, only two wires are
required. When battery operatio n is used, the C terminal does not need to be
connected.
Provision is alsomade for separate heating and cooling transformers via separable Rc
and Rh terminalswhich are connected via factory--installedjumper wire.