Taco SR503-EXP with Venstar T5800

Old 08-17-14, 01:00 PM
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Taco SR503-EXP with Venstar T5800

Trying to replace thermostat with a Venstar T5800. On this thermostat it requires a common wire. Currently I only run heat via a two wire setup. The thermo wire has a green wire that is not in use. Can I use this wire as a common? I have a Taco SR503-EXP and it has a terminal block on the left with a 24vac terminal block. Will this power the thermostat?
Old 08-17-14, 02:57 PM
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Turn off power to the control, label and remove the thermostat wires and take an ohm reading at the terminals that I highlighted. (Using the red and White that you are adding a common to)
Red to blue
Red to yellow
White to blue and
White to yellow.

Post back with your results.

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Last edited by Houston204; 08-17-14 at 03:30 PM.

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