The Dial controller is synonymous to all swamp cooler owners as the de facto controller; It has some flaws. The relays are enclosed making the thermometer read high and since it’s a bang-bang controller, the swamp cooler turns on and off pretty frequently and thus Dad decides to migrate the controller to the ecobee thermostat used by the furnace.
The issue with swamp coolers are they do not use a low voltage thermostat, so for the Ecobee to send cool, we would have to use a relay to convert the 24 volt signal to 110Vac. That’s where the White Rodgers come into play.
Background
Prior to switching the swamp cooler thermostat, the reason to integrate it with an ecobee Smart thermostat was because Dad already swapped the heater thermostat to one. The reasoning to go ecobee is the ability to position remote sensors around the house. Comfort zones can be assigned to unique sensors to ensure the house is adequately heated. For example, there’s a sensor in the North bedrooms due to their tendency to run colder than the rest of the house.
The way the house is laid out, the heater thermostat is on a pony wall that’s shared with the kitchen, this makes it very difficult to run new wires. Fortunately, the thermostat wire was a 6 wire, which was sufficient to control the furnace and the White Rodger!
Design
The White Rodgers requires 3 inputs.
| Thermostat sends for | White Rodger behavior |
|---|---|
| Blower (G) | A timer that holds back the Fan relay on a timed delay between 30 to 120 seconds |
| Cool Stage 1 (Y1) | Pump Relay is switched to power the pad pump wire |
| Cool Stage 2 (Y2) | The Fan relay nominally closes the lo speed motor wire and when Y2 switches the relay, the hi speed motor wire becomes hot. |
Originally, Dad thought he could directly connect the ecobee to the White Rodgers but discovered after reviewing the circuit board the voltages won’t match at all and had to isolate the ecobee (powered by the furnance’s 24Vac transformer) from the White Rodgers’ 27V rectified output.
