How do I control my attic fan with outdoor and attic temperature sensors?

Other Devices & Integrations Climate Control & Temperature Sensors
#1

First, I have a basic system setup that just turns on my exterior lights at sunset for a few hours and I’m looking to expand it to control some additional home functions.
I live in So. Cal and the Summers get pretty hot. I have an attic exhaust fan and one in the garage too.
These have basic hardwired temperature controls so they click on at 90 degrees and run all day long on hot days.

Here’s the hardware I’d install:
a) Basic temperature probes in the attic, garage, and one outside (in the shade under the eaves).
b) Replace hardwired temperature sensors on the exhaust fans with zWave switches.

Here’s what I’d like to program with my VeraLite:
When outdoor temperature is above 80 then if the temperature outside is 5 degrees cooler than the attic then turn on the fan, else turn the fan off.

This way the attic fan would only run when the outside temperature is 5 degrees cooler than the attic or garage and would cool the attic/garage down to 80 degrees.

Is this possible to program with the VeraLite?
Any recommendations for a good temperature only sensor?

Thanks for any responses!

#2

This absolutely can be done. I’ve done a much more complex scenario with my whole house fan. You’d likely need write custom Lua code and put it in a scene that runs at a set interval. I’d probably do it every 15 minutes or so as to not over burden your controller. If you’re comfortable with writing code working off an example, I can post my whole house fan code for you to look through.

#3

Use PLEG for your automation.

I would use the Weather Underground PLugin for your Outdoor temperature.

#4

I would like to do something similar with my whole house fan as well and I would appreciate seeing your lua code.

Sent from my iPhone using Tapatalk

#5

[quote=“314Patrician, post:1, topic:189065”]First, I have a basic system setup that just turns on my exterior lights at sunset for a few hours and I’m looking to expand it to control some additional home functions.
I live in So. Cal and the Summers get pretty hot. I have an attic exhaust fan and one in the garage too.
These have basic hardwired temperature controls so they click on at 90 degrees and run all day long on hot days.

Here’s the hardware I’d install:
a) Basic temperature probes in the attic, garage, and one outside (in the shade under the eaves).
b) Replace hardwired temperature sensors on the exhaust fans with zWave switches.

Here’s what I’d like to program with my VeraLite:
When outdoor temperature is above 80 then if the temperature outside is 5 degrees cooler than the attic then turn on the fan, else turn the fan off.

This way the attic fan would only run when the outside temperature is 5 degrees cooler than the attic or garage and would cool the attic/garage down to 80 degrees.

Is this possible to program with the VeraLite?
Any recommendations for a good temperature only sensor?

Thanks for any responses![/quote]

I have two of these to control my two attic fans

I just set the temperature to turn on and off on the digital display

#6

hsmair, I have some questions on how you use that line voltage thermostat to control your exhaust fan. I want to cool my garage with an exhaust fan when the garage temp is > 90 (set point = 90). I would run the temp probe thru my wall to outside and measure outdoor (air intake) temperature. When the differential is >4, I would like the fan to be on. Do I use the heating or cooling mode. I interpret their installation manual as indicating that I should use the heating mode??
Thanks

#7

314Patrician, What type of zwave sensor do you use for the outdoor temperature? How well does it hold up to the weather conditions. I have trouble with the salty air in area, killing indoor sensors within a year or so. I suspect outdoor sensors would die even faster unless they were well sealed.
After doing some searching, I found the Fibaro zwave window door sensor to which one can attach a DS18b20 external temperature probe and monitor outdoor temp with an indoor sensor.

#8

[quote=“aecchalet, post:6, topic:189065”]hsmair, I have some questions on how you use that line voltage thermostat to control your exhaust fan. I want to cool my garage with an exhaust fan when the garage temp is > 90 (set point = 90). I would run the temp probe thru my wall to outside and measure outdoor (air intake) temperature. When the differential is >4, I would like the fan to be on. Do I use the heating or cooling mode. I interpret their installation manual as indicating that I should use the heating mode??
Thanks[/quote]

Yes I use the heat mode.
My attic fan turns on when the temp rises above 90*
When the temp returns to 90* in the evening after the sun goes down it turns off

I purchased my two on Amazon

http://www.rancoetc.com/ranco-etc111000000-digital-temperature-controller-p-86.html

http://www.etcsupply.com/manuals/ranco_etc_instructions.pdf?osCsid=n3q19skksrrlhp7dap5sorhc00

Howard