Temperature Based Exhaust Fan Control

Good morning,


I have a client for whom I have installed a Radio RA2 system. The system consisted of an exhaust fan for their conservatory/greenhouse which I had setup to be controlled by an 8ANS and a system time clock to turn it on and off several times a day.


My clients have now asked me to change this setup around so that the exhaust fan will be controlled based on the temperature within the room.


The room has s single Tekmar thermostat controlling a zone of radiant heat and they do not want me to remove this.


My thought is to install either a Touch Pro (Jumping/Pulling power from the Tekmar) or to install an HVAC Controller and Wireless Temp Sensor thus allowing me to then turn the exhaust fan on and off based on my clients desired hot and cold temperature set points.


I would like to know if one option above is better than the other or if their is an alternate solution you may suggest.


Thank you.

Here's an idea that may work for you:

Install a Hubitat Elevation hub (~$100 now). It speaks Lutron via Telnet.
Install a z-wave or ZigBee temperature sensor (~$40)
Set up an automation in Hubitat to turn on based on temperature.

If you do this, you'd probably want to do the time of day schedules from the Hubitat as well to minimize tracing of control.

Thank you for your suggestion. It is a possibility to do it as you suggested however I would prefer to keep it within the Lutron environment without adding another sub system to the mix.

I get it - it's a never ending quest to keep things simple! When needed, the Hubitat is one of the easiest and cheapest ways to add additional and more complex lighting automations to a RadioRA 2 system. Example: I have an automation that sends a push notification and turns on the laundry room lights (Lutron) when the washing machine or dryer finish their cycles (z-wave appliance power monitoring switches).

That is very cool and convenient as well. I will definitely take a look at it as there are many times I wish RA2 had some basic logic that can easily be added as with their Caseta and the use of IFTT. I have honestly not done much with ZWave and Zigbee as my early attempts (years ago) proved problematic. I try and stick with the things I know are rock solid for my clients therefore lessening my service calls and or bad mouthing. Thank you again for some insight and your replies. Much appreciated!

Yes, I started out with some z-wave lights. I found they weren't always reliable, particularly from a timing perspective. That's when I moved to Lutron lights. Which really are (almost) always reliable. I've found that devices other than lights don't need the same timing consistency. So then z-wave and zigbee work. The Hubitat lets one combine Lutron lights with the other devices. And even allows for more complex automations of Lutron lights without going to a Control4 level of cost and complexity.

And the Hubitat works all locally (as long as your devices do). No need to go to the internet and IFTTT. Which also applies to Caseta Bridge Pro setups (as it has Telnet access).

Use the 8ANS to enable/disable a line voltage thermostat. They make some in-wall ones that decent looking.

Thank you RandyC. I was initially going to just use a line voltage thermostat however the way the fan is installed and its location prevents me from doing so. The contractor placed the fan above the exterior door and being the room was already completed we were not allowed to cause any damage to snake wires etc. we had to bring the power and switch leg off a sub panel from within the pool cabana in an overhead bridge way where the HVAC line sets connect to the house. Kind of a convoluted setup but was only option we had to get it to work.

I appreciate the suggestion though.

Good morning BillD, Looks like my only option is to use a setup like you had suggested as RA2 does not support the functionality I was hoping for with the available HVAC components they have, only within HomeWorks. That being said have you used a ZWave thermostat that you would recomend? I of course will do some research but if you had used something you found to be reliable and of good quality I would start there. Thanks again

Sounds like a penny wise, pound foolish client. By the time to you hack together something, you could have purchased a Lutron RA2 Thermostat and a RA2 switch or RF relay for the exhaust fan and have seamless integration.