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Fan not running in AUTO for newly installed HoneyWell RET97E5D1005/U Wi-Fi

Fan not running in AUTO for newly installed HoneyWell RET97E5D1005/U Wi-Fi


  #1  
Old 12-28-13, 08:40 AM
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Fan not running in AUTO for newly installed HoneyWell RET97E5D1005/U Wi-Fi

Hi,

I couldn't find any existing incident resembling my situation, so here goes.
I have conventional gas heat/forced hot air heat system (along with ac using the same air handler). I replaced my old programmable thermostat (run on batteries) with new honeywell RET97E5D1005/U Wi-Fi thermostat.
I researched all about the need of the C-wire. Fortunately my wires to the thermostat has two extra unused wires.
Using one of the extra unused wires to connect to Common at the air handler, i was able to power up my new thermostat fine. Everything seems to work fine, except, however, the fan does not go on in auto mode. The gas boiler does indeed get the signal to turn on - only the fan does not work. If i turn the fan on in manual mode, the fan works. I called Honeywell support, and they are saying there is nothing wrong with the thermostat ( I tend to agree since i purchased two new thermostats and both have same symptoms for this particular zone - i find it unlikely that both have the same defect.. but then again.. who knows..).
If i uninstall the new thermostat, and install my old one, the auto mode works fine.
If i measure voltage drop across RH(R) wire and W (as well as from RH to C), I get 19-20 volts (instead of expected 24volts). Could that be the cause of my issue? could the current drop to the blower be too much when adding the new thermostat into the mix? Any suggestions? Unfortunately, I'm not exactly sure the make of my air handler ("janitrol" sounds familiar.. but not sure..), but attached are some photos of the schematic.

thanks for your help!
 
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  #2  
Old 12-28-13, 09:36 AM
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Welcome to the forums.

I have conventional gas heat/forced hot air heat system
Good thing you supplied pictures because, as far as I can see, you don't have a conventional system and you don't have a furnace. That picture shows a fan coil unit which means it gets supplied hot water from some type of boiler or water heater.

Based on that. You need to set the programming in the thermostat to electric heat instead of a gas furnace. When you do that the thermostat will turn on the blower with the call for heat.
 
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Old 12-28-13, 09:41 AM
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Problem solved!

I called Honeywell support one more time to let them know that the AUTO seemed to work if i reverted to my old thermostat, and to see if that was a clue to anything.

This time, the support person walked me through some internal setup - it turned out that by default, the new thermostat is set up to rely on the furnace/boiler to initiate the fan when in AUTO mode. She helped me reconfigure the thermostat so that instead the thermostat drives the turning on of the fan when in AUTO mode. With that change, everything is working now. Too bad they didn't tell me this last night.

anyway, thanks for listening!
 
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Old 12-28-13, 09:45 AM
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thank you so much for your response! you're spot on! and thanks for the clarification on what i have! I just sent a response to my initial post pretty much confirming what you are saying, not realizing you had responded.
 
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Old 12-28-13, 10:19 AM
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No problem.... it's all good now that it's working properly.
 
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Old 03-13-14, 02:33 PM
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Hello do you know what steps is require for fan to work in auto mode I have same problem
 
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Old 03-13-14, 03:24 PM
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Welcome to the forums.

This is a complicated problem. The answer is different for every setup . You really should have your own thread.

We need the make and model of the thermostat.
Is this a newly installed thermostat ?
Was it working before ?

You will need to look at the wiring on the back of the thermostat and tell us what color wire goes to which labeled terminal.
R = red
W = white
etc..........
 
 

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