going from an old honeywell to a venstar t5800 having issues


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Old 04-21-14, 03:19 PM
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going from an old honeywell to a venstar t5800 having issues

I swapped out a old 4 wire tstat for the touchscreen t5800 with 5 wire. The old tstat had only 4 wires running and I located a blue (c) wire that was not in use and hooked it up to both furnace and tstat. The issue is that the venstar will still not power on. I even called a HVAC guy out and he said everything looked fine and that it was probably the tstat. Now the retailer is saying it is probably an error on the tech instead of the tstat. Anyway, is there any other reason why the screen would be dead. My old tstat did have a jumper from r to rc. The new tstat does not have a rc port.

Frustrating since I paid for an hvac and the tstat is still not working and now the seller (ebay hvac retailer) wants me to send it in for testing. And then they will determine if it is broke or not and then decide to send me a replacement or the original back. What a joke. i will never buy another item like this unless it is from a brick and mortar store.
 

Last edited by beemer2000; 04-21-14 at 03:37 PM.
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Old 04-22-14, 06:42 PM
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Can you measure 24 volts AC between R and C at the stat?
You may have a splice between the stat and the furnace.
 
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Old 04-27-14, 11:40 AM
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I don't know. I think the HVAC guy said there was but he seemed in a hurry. I am completely new when it comes to volt testing and HVAC systems. I would just put the + post on the multimeter to the C and the neg to the R?

I put it off again till today. I want to make 100% sure before I send the unit back to the retailer cause I know I won't see it again for a month.

Is there anyway just to check the tstat. Could I just go out to the furnace. Take some wire and run directly from R to the C on the tstat just to see if it powers on. They are both 24v right? Since I now I am getting power from R.

On the splice, there is wires screwed into the C terminal at the furnace. Other than the blue C wire going to the house tstat. I asked the HVAC what they were and he didn't know and didn't want to find out apparently.
 
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Old 04-27-14, 11:50 AM
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Yes, you can run new wire or take your stat to the furnace and connect R and C.

The second C wire at the furnace feeds the outdoor unit...
http://i151.photobucket.com/albums/s...coilwiring.jpg
 
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Old 05-02-14, 03:15 PM
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Finally measured the voltage. It read 26 volts to the r and c terminals. I sent the venstar back to the retailer and they said it turned on and they are sending it back.
Is there anyother reason why it is not powering on. If I am getting the proper voltage then they are either lying and do not want to return the unit or there is something i am missing.

Thanks
 
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Old 05-02-14, 04:09 PM
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I have seen problems occur when the wire gauge is 22 instead of 18 and the distance is well over 100 feet.
I have also seen people unwilling to accept returns.

I have a paper weight that looks like a laptop to prove this.
 
 

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