Ask Experts Questions for FREE Help !
Ask
    leedfoster's Avatar
    leedfoster Posts: 2, Reputation: 1
    New Member
     
    #1

    Mar 23, 2007, 10:46 AM
    R RC jumper and voltage + fan issue
    I was having an issue with my Honeywell Tstat RTH7400 --- when heat was turned on the fan would run in the auto position but would not run in the "On" position (regardless if it was heating or not it would not run in the "on" position). I called Honeywell and they could not figure out the problem. I got out the voltmeter and found the following:

    Red wire carries 24 volts to green and yellow but not to white
    Blue wire carries 24 volts to white but not to yellow or green
    Green runs fan
    White runs furnace
    Yellow runs a/c

    So I ran both Red and Blue into the R & Rc terminals with the jumper connected. This seems to have fixed the problem and everything runs the way it should.

    Question: Is there any issue with running both 24v wires into the jumpered terminals? Would the system run properly if the jumper was removed?

    Thanks is advance.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
     
    #2

    Mar 24, 2007, 07:51 AM
    Here is a link to your t-stats instructions.

    http://customer.honeywell.com/Techli.../69-1900EF.pdf
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member
     
    #3

    Mar 24, 2007, 09:49 AM
    In some cases, life is complicated by having separate transformers for heating and cooling. In such cases, it is important to have both wires to a control connected to same transformer. If you properly match the phases, you can connect the transformers to each other. If your system works the way it is, it means either you have the red and blue wires both running to the same transformer, or the 2 transformers are in phase.

Not your question? Ask your question View similar questions

 

Question Tools Search this Question
Search this Question:

Advanced Search

Add your answer here.


Check out some similar questions!

Noma 5+1+1 thermostat - jumper? [ 1 Answers ]

I just purchased a Noma 5+1+1 heating/cooling programmable thermostat to replace the one that came with my new home. I have a furnace and an A/C unit. The wiring on the old one is as follows: Green wire > G Orange wire > Y White wire > W Red wire > RC jumped to RH The new thermostat has...

Ceiling fan w/ remote issue... [ 4 Answers ]

I bought some long life fluorescent lights for my fan with remote. After I tried to power the lights on it flashed on, then off. Now, neither the fan nor the lights will power on with the remote or the pull strings. It only occurred after this happened that the lights won't work with dimmers. ...

Wiring issue with a Hunter Ceiling fan [ 2 Answers ]

Thanks in advance for anyone who can help me. I just moved into a brand new home and the Master Bedroom is pre-wired for a ceiling fan. It has two wall switches, one to control the light and one for the fan. The Hunter fan has a black, a white, a black/white and two green wires. The prewire...

Identifying jumper pin [ 3 Answers ]

Someone posted that their floppy drive was recognized but when trying to use, it says to insert floppy. I have the same problem and it was suggested to "remove CMOS jumper pin from Motherboard. I've never done this. Can someone please tell me where this is located or where an image might be...


View more questions Search