System hookup/wiring questions


  #1  
Old 10-15-13, 11:51 AM
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System hookup/wiring questions

Hey yall,

Recently had a new system installed. It seems to be working well but as part of my meticulous nature I am documenting everything done for the future. The wiring is what is raising an eyebrow for me and it may just be my lack of knowledge and understanding. We had the following installed;

FURNACE LENNOX SL280UH090V48B-03
COIL LENNOX CX34-44/48B-6F Coil/3.5-4Ton/Cased
AIR CONDITIONER LENNOX XC14-047-230-04
Honeywell TH8321U1006 thermostat

From what I understand the heater is dual stage and the AC is single. Furthermore when I look at the wiring for the thermostat it looks as if the second stage from the t-stat is not hooked up. Here are a couple pix.

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  #2  
Old 10-15-13, 12:04 PM
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You are correct, the second stage control is not connected. The second stage heating is connected to the W2 terminals.

What this means is that the installer used the timer feature of the furnace to energize the second stage. Often this timer is set to ten minutes and so after ten minutes of single stage operation the furnace will shift to the second stage, even if it is only for a few seconds, until the temperature at the thermostat reaches the cut off point.

I have mine set so that the second stage comes on at three degrees below the primary set point. Since I run my furnace manually it means that it goes to the second stage immediately when I first turn up the heat in the morning. Today it was 63 degrees when i turned up the heat to 68 and so the second stage came on and the house heated up much faster than if I had used an intermediate temperature of 66 and then came back to raise it the second two degrees. The furnace will not again use the second stage until tomorrow morning.

Not having the second stage wiring connected means that you are not receiving the full benefit of your two-stage furnace. Since it appears that you DO have a sufficient number of conductors at the thermostat the installer was simply too lazy to properly connect the wiring.

REMEMBER, there is also a DIP switch setting that must be changed on the furnace control board to use the second stage via the thermostat rather than the timer function.
 
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Old 10-15-13, 12:39 PM
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Thanks Furd,

So we are supposed to be getting a post sale visit to make sure everything was 'installed correctly' is this something we should demand be corrected with the rest of the gripe list?
 
  #4  
Old 10-15-13, 02:19 PM
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Absolutely! The wiring is already in place so all it requires is connection at the thermostat and the furnace along with changing the setting of the DIP switch. In colder weather your furnace will run longer on the first stage and the temperatures throughout the house will be more even. Biggest plus is that you will likely save some fuel as well.
 
  #5  
Old 11-25-13, 01:26 PM
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Well sorry took so long to get back to this but life can get busy. The guy came for the 'inspection' and told me "You dont need that wire its better to let the heater decide when to go into the second stage".

So I guess I will look into what the proper manner is to fix it myself.
 
 

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