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Old 01-25-2013, 08:29 PM   #1
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Default Honeywell / Computer Cord Mod

Hey everyone,
Being an industrial engineer and not a EE... I need some help. I have a Honeywell RTH110B thermostat and an old computer cable. I would like to combine the two in order to power a small light for heating and a fan inside my fermentation chamber.

The thermostat I believe can handle 24v (not sure on amps) and act as a switch based on temp. The computer power cord has an input of 110-240v (1amp) and output of 19Vcc (2.1amp). Can I splice the output line into the thermostat connections (like hooking up a heater) and then supply a small bulb/fan? Or am I burning doing my house and better off spending the $50 on a controller...

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Old 01-25-2013, 11:21 PM   #2
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That model thermostat is meant to be use as a low-voltage hvac controller. Meaning its outputs are to be used to control relays, and not directly drive loads (like heaters and compressors).

So to cobble together a heater controller, you'd need to add a 110vac to 24vac transformer and a relay with a 24vac coil and points sized for your heater amperage. Then, with the thermostat set for heating mode it would switch the relay which would carry the heater load.

By the time you combine the transformer, relay, and a box to hold everything, the cost might make an STC-1000 look pretty good...

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