Auxiliary Inputs
How do I wire and use the Auxiliary Inputs?
Aux1 and Aux2
On each of the EcoNet enabled furnaces and air handlers there are two auxiliary inputs that may be used for external controls or safeties. Most common would be a float switch. Float switches may be found in secondary drain pans, condensate pumps, or in some specialty trap assemblies. Other external safeties may be freeze stat or some sort of custom control.
The EcoNet equipment is wired on a 2 wire communicating bus and 2 wires for 24v control power. None of these 4 wires should be broken by any type of safety. Why? Because if we break communications we will end up signaling any number of alarms or alerts that will not provide a technician or homeowner with information that would lead them to a safety such as a float switch. Switches on safeties are intended to break a 24V circuit, but they aren’t very good at allowing data to flow when the switch is closed. We also do not want to break either of the 24V wires because alarms will also be triggered. This IS the reason we put auxiliary inputs in the system.
The inputs can be customized to look for normally open or normally closed contacts. They can also shut a portion or all of the system down with or without an alarm. We’ll cover the choices below.
On the furnace there are terminals designated as Aux1, Aux2, and Aux C. Aux C is an output voltage always present, the circuit sends a voltage out and looks for voltage at Aux 1 and Aux 2. On the Air handlers there are wire leads for the same terminals. These inputs are only available when using the EcoNet Thermostats because they must be configured in the thermostat.
In the thermostat, click on the menu, then settings, installer, and select the air mover (either Furnace or Air Handler). You must select what condition your control element is. For example, most if not all float switches are normally closed switches. This means they are a closed circuit until water triggers the switch which breaks the circuit to open. You would set the switch for N.C. If you had some sort of control that was normally open that closes in an alarm condition, then you will set the control for N.O.
Next set your option of how you want the system to respond. Let’s start with “Float Switch Alarm”. When configured, if the float switch opens, the system will recognize that and shut the cooling off and send an alarm to the Thermostat (and if the customer has Wi-Fi configured to his app, a text and email) letting the customer know the float switch has tripped and shut the cooling down. Below are the alarms you would get. You can click on them for explanation.
A201_F Float Switch Trip - Furnace Aux Input 1
A202_F Float Switch Trip - Furnace Aux Input 2
A201_A: A Float Switch Trip - Air Handler Aux In 1
A202_A: A Float Switch Trip - Air Handler Aux In 2
Caution: the float switch alarm selection will only shut down cooling. If you have a condensing gas furnace or system with a humidifier that can cause water damage, you will have to get creative or use an alternate alarm designation. If you only have a float switch or two, it would be best to wire your safety circuit from Aux C, through the float switch back to Aux 1 and put a jumper from Aux1 to Aux2. Configure Aux1 to N.C. Float Switch Alarm, and configure Aux2 as “Shutdown No Alarm”. When the float switch opens, Aux 1 will trigger the cooling off but more importantly it will trigger the alarm. Aux2 will shut any heating or humidifying down as well. No need for an alarm, because Aux 1 handled that.
Your choices for configuring the inputs are:
Float Switch Alarm – Shut down cooling, alarm
Shutdown– Entire System shut down, no alarm
Shutdown Cool– Cooling is shut down, no alarm (could be used for freeze stat)
Furnace Lockout– Furnace shuts down gas heat operation, but heat pump or cooling is allowed – no alarm.
Furnace Lockout Alarm – Shuts down furnace and alarms. This could be used if it were somehow tied into a smoke or CO detector.
Heat Pump Lockout – Shuts down heat pump heating with no alarm.
We have been asked if the auxiliary inputs can be configured with an EcoNet thermostat then remove the EcoNet and use a legacy thermostat. The answer is a resounding NO. Once you remove the EcoNet thermostat, you lose the Auxiliary inputs. Where would you read the alarm anyway? If you want the benefits of EcoNet, use the EcoNet control. Besides you can break any wire you want when you wire it legacy, then you get to find out why the equipment isn’t running.
