Very new to SmartThings, so hoping someone can guide me on a solution to controlling my in-line Duct Fan.
I have a home that has an installed inline Duct Fan (Fantech FG6 - http://www.fantech.net/products/fans--accessories/circular-duct-fans/fans-for-circular-ducts-with-ac-motors/fg/fg-6-centrifugal-inline-fan/), that is controlled manually via a Variable speed switch (http://www.fantech.net/products/fans--accessories/electrical-accessories-ventilation/speed-controls-electronic/wc/). The problem is I have to manually turn on the fan when I want to have it come on, and then leave it running (or run downstairs every time the HVAC comes on and off). It’s purpose was to provide extra airflow to the downstairs storage area, which works fine if/when it’s on. I just want to automate the turning on/off of it.
I was hoping to control this fan via SmartThings, by changing the existing variable speed knob switch with a controllable relay (I’m thinking the FS20Z-1 ??), and then monitoring my HVAC system for when the fan motor goes out of Idle (either heating or cooling). I have a Honewell THX9421R5021WW thermostat (Redlink connection), so am using the Honeywell 9000 Thermostat device driver to talk to it (I’ve tried also the Honeywell VisionPro Thermostat). SmartThings controls it just fine, but when I try to use CoRE to monitor the ThermostatOperatingMode to determine when it changes from Idle, I ran into issues. The problem is, if I manually reset the cooling (or heating) setpoint, SmartThings receives a ThermostatOperatingMode event such as “Cooling to 72 F”, and my piston is triggered. Great. BUT, if I simply leave the thermostat at a given setpoint, and it comes on and off to maintain that setpoint, NO event is ever posted to Smartthings when the air comes off or on. SmartThings always reports the status as Idle. I only get an event posted IF I reset the setpoint to make the air (or heating) come on, not when it comes on/off by itself to maintain the setpoint. So, monitoring for change of Idle won’t work.
So, my current thought is to put some sort of relay(?) on the furnace system (or Thermostat, which apparently talks to an Equipment Interface Module sitting next to the furnace), to monitor when the blower motor is on or off. This is where I am totally lost, as I know nothing about relays, etc. Can anyone suggest to me a way of simply monitoring when the blower comes on and off, so I could control the duct fan? What sort of “relay” might I need to wire into the furnace? Also, is the above FS20Z-1 the correct device/relay to replace my Variable Speed relay with? I was thinking of some sort of “dry contact” monitor on the furnace, that I would monitor for, then send a signal to the FS20Z-1 to turn on/off the fan?? But again I’m lost with relays, contacts, etc, as to what I would need.
Sorry for the long question, but wanted to provide all the relevant details to hopefully help someone help me.