Nest Issue


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Old 12-28-12, 08:00 AM
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Nest Issue

Hi!

I have a new construction home, A/C and Gas furnace. 4 wires on system, white, yellow, green and Rc (previously had a jumper between Rc and Rh). I installed a Nest on Christmas day and now, it will run the furnace, but not kick on the fan to blow the heat through the house unless I reset the furnace via the breaker box, and then it will cycle like this again and not blow heat.

Any ideas??

It's wired correctly. Nest customer service was....not helpful, yet.
 
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Old 12-28-12, 08:12 PM
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The t-stat does not turn on the fan for heat mode, just cooling.

The issue may be the furnace itself.
 
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Old 02-02-13, 05:43 AM
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The problem is that it will kick on the furnace but not actually blow heat and the furnace will just heat cycle. The only fix is to reset the furnace. What's especially weird is that this ONLY occurs on weekends.
 
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Old 02-02-13, 06:56 AM
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Take the G wire off the -stat, and see what happens. If that furnace fan never comes on, then it's the furnace itself.

A correct working system, should be like this.
-stat calls for heat
-furnace lights up.
-flame runs for 1-2 min
-then the main blower comes on.
-after temp met set point, burners shuts off.
-blower run another 2-3 min.
 
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Old 02-06-13, 08:20 PM
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Thanks. I'll try that. We had nest ship us a new one and so far so good. Until tonight. When it powered up the furnace. And no fan. Again. Furnace is a temp star 95 BTW. New construction. Any insight on that?
 
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Old 02-07-13, 05:07 PM
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a gas furnace has a control board that controls the fan with a call for heat, not the thermostat. Your problem is likely a failed control board
 
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Old 02-10-13, 06:42 AM
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I thought that but the original thermostat that came with the house has NO issue at all. And manually controlling the temperature works fine. It's a weird occurrence. I'm calling the company that installed the furnace tomorrow to ask if they have had issues with this.

Thanks again!
 
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Old 02-10-13, 07:25 AM
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what is the original thermostat? Make and model? Is there any type of setting on it for gas/electric. If it is set for electric then it will call for the blower with a call for heat. This is a cheap work around for furnaces that have a failed blower heat relay on a control board.
 
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Old 02-10-13, 10:17 AM
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I agree with Kevin, and if the blower was forced to come on, it was coming on too soon, and also the air flow may of been on a higher speed than it should of.
 
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Old 02-11-13, 05:54 AM
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It's a hunter 46655 and it was set to HE ie electric but when i set the nest to electric forced air the fan dos run immediately but blows cold. Any ideas?
 
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Old 02-11-13, 06:47 AM
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It will blow cold. There is no difference in how the Nest is operating the fan vs the old thermostat. When set to electric heat the blower is pulled on at the same time as a call for heat, so the furnace has not had a chance to warm up yet. The correct operation is that it is set for gas heat and the furnace control board has a delay timer built in to tell the blower to come on 60-90 seconds after the call for heat initiated.

If the blower does not come on on its own with the thermostat set for gas forced air then it is a problem with the furnace control board, not the thermostat. If you have a new construction home then call the hvac contractor that put the furnace in.
 
 

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