Results 1 to 5 of 5

Thread: 24V terminal to operate fan independently

  1. #1
    Junior Member

    User Info Menu

    24V terminal to operate fan independently

    Hi,

    I build electronic HVAC scent diffusion equipment for residential applications. I'm in the process of determining what bells and whistles I need on a new timer interface. R&D testers have suggested putting a 24V terminal on the box that becomes live when the scent diffuser is in it's active mode. In the case of my system at home, the scent diffusion starts at 4:00pm and shuts down at 11:59 pm M-F. I need the fan running during that time in order to distribute the fragrance or oil to the registers.

    My question is this: is it worth designing that terminal into the timer or are the new thermostats capable of running the fan based on a time parameter? My target market is mid to upper end, new residential for my initial market launch.



    Thanks for any help.

  2. #2
    HVAC Thermostat Specialist

    User Info Menu

    I would put in a relay but it need to isolate G at the control board from G at the thermostat because almost all thermostats connect G to Y when in a rest state.

    Click image for larger version. 

Name:	fan isolation relay.jpg 
Views:	229 
Size:	15.2 KB 
ID:	931
    Last edited by hvactechfw; 10-09-2014 at 06:30 PM.

  3. #3
    Junior Member

    User Info Menu

    Quote Originally Posted by hvactechfw View Post
    I would put in a relay but it need to isolate G at the control board from G at the thermostat because almost all thermostats connect G to Y when in a rest state.

    Click image for larger version. 

Name:	fan isolation relay.jpg 
Views:	229 
Size:	15.2 KB 
ID:	931
    Hi,

    Thanks for the reply! 24V AC. ...what amps or any other specifics?

    Lonnie

  4. #4
    HVAC Thermostat Specialist

    User Info Menu

    amp rating should be 1 amp or less. A simplistic relay can be found on amazon.

  5. #5
    HVAC Thermostat Specialist

    User Info Menu

    Quote Originally Posted by hvactechfw View Post
    I would put in a relay but it need to isolate G at the control board from G at the thermostat because almost all thermostats connect G to Y when in a rest state.

    Click image for larger version. 

Name:	fan isolation relay.jpg 
Views:	229 
Size:	15.2 KB 
ID:	931
    The thermostat has a manual fan auto/on switch (most do) the Y&G are connected while the stat is in the "rest state". If the thermostat uses a digital fan auto/on switch Y&G are NOT connected in the "rest state". Each has a seperate relay.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •