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  1. #1
    Join Date
    Jul 2006
    Posts
    35
    Hi! This is my first post here...

    I have to go to a clients house in the morning and he's giving me a hard time about this...and i've talked to some other shops and no one seems to be able to give me a clear direct answer for this. I'm hoping someone here can help.

    On newer homes...there is an exhaust ventilation fan that turns on the furnace fan as well. When the client turns on the vent switch on the main floor...the central air comes on...with the vent fan..which it shouldn't. I'm assuming this is feeding back a voltage back up through the thermostat G wire and hitting Y. I know that i need to install an isolation relay to solve this..i just don't know where...or what connects to the coil...and what connects to the normally open or closed. Does anyone out there have a diagram or can help me? I need to go there in the morning...and i really need help with this.

    Please and thank you.

    [Edited by desol on 07-14-2006 at 01:31 AM]

  2. #2
    Join Date
    Jul 2006
    Posts
    35
    I was kind of thinking that i should 'parallel' off of the two wires going to the furnace control(g,c) from the vent fan...to the coil on the relay. Then put the 'g' wire going up to the thermostat on the normally closed contacts on the relay...

    So when the exhaust fan comes on...it powers the relay and furnace blower...but opens the normally closed contacts going up to the thermostat...stopping the feedback?

    This would mean the client could only use the ventilation feature or central air...but not both at the same time? Still, i don't know if this is the proper way to do this...

    Anybody?



    [Edited by desol on 07-14-2006 at 01:23 AM]

  3. #3
    Join Date
    Jul 2006
    Posts
    35
    C'mon...

    There's alot of knowledgable guys here...someone must have seen this somewhere or have some kind of input? I can't be the only one that's fussing around with relays..

  4. #4
    Join Date
    May 2006
    Location
    east central indiana
    Posts
    1,117
    desol:
    As you work "in the field", why not register as a professional. Then you can post this on the tech forums, where it will get a better response.

  5. #5
    Join Date
    Jul 2006
    Posts
    35
    I will... Good idea.
    It's just that i don't have that much time...this was where i first posted...it's getting late and i was hoping for a little 'feedback' before i hit the sack...and i have to wire this up tomorrow...as simple as it should be.

    I just arrived here...so i was hoping someone would be like.."oh yeah...i've seen that a hundred times...just do this..." lol


  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,125
    Yellow.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Jul 2006
    Posts
    35
    Excuse me? I'm not sure what your getting at?
    You have to be more 'specific'?

    Thanks.

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