Trane XL16I 2 stage heat pump - how to verify it is in stage 2


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Old 01-29-07, 07:39 PM
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Trane XL16I 2 stage heat pump - how to verify it is in stage 2

I have a Trane XL16I 2 stage heat pump and have suspected the outdoor unit has never run in stage 2 even though the Vision Pro thermostat goes to stage 2 and the inside blower ramps to high speed. The output air gets cooler when the blower ramps up for stage 2. Recently traced wiring and discovered the brown cable wire connects in the heat pump to the yellow / red stripe wire but was not connected to anything in the fossil fuel kit. I connected the brown wire from the thermostat wire (which is connected to stage 2 in the thermostat) to the brown wire leading to the heat pump. I get a sense now the air is warmer when in stage 2; however, I can not tell any noise difference in the unit outside. Should the outdoor fan run at a higher speed or the compressor at a higher noise level when in stage 2 versus stage 1? If not, what does control the outside fan speed? It always seem to run at just one speed. Thanks!
 
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Old 01-29-07, 09:17 PM
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The outdoor condenser unit (compressor & fan) will always run at one speed and will continue to run when the 2nd stage (heat strips) heat is called. The only scenario in which outdoor fan would stop would be in the defrost mode. What happens here is that the compressor actually reverses to cooling mode to defrost the outside condenser coil. Furthermore, the heat supply during this time comes from 2nd stage heating.
 
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Old 01-29-07, 09:55 PM
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Wink

If that 2 stage heat pump is wired right you should have a Y1 and a Y2 at the tstat and the XL16i should kick in.But what do you have for this fossil fuel kit. Whats your other heat????? How have they got the OT tstat set outside??
Yes the condenser has a multi-stage fan. Also you do have a V/S blower on this unit inside dont you????
 
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Old 01-30-07, 06:21 AM
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Originally Posted by Ed Imeduc View Post
If that 2 stage heat pump is wired right you should have a Y1 and a Y2 at the tstat and the XL16i should kick in.But what do you have for this fossil fuel kit. Whats your other heat????? How have they got the OT tstat set outside??
Yes the condenser has a multi-stage fan. Also you do have a V/S blower on this unit inside dont you????
Correct...tstat has a stage 1 compressor and a stage 2 compressor (as well as auxilliary and emergency heat) and its all wired. Also have the 2 stage variable speed gas furnace as the aux / emergency heat source. The system all works; however, I never felt the stage 2 of the heat pump was kicking in. Regardless of which stage the system was running, the unit outside always seems to "sound" the same and the outdoor fan seems to always run at one speed. The disconnect between the stage 2 compressor with the tstat and the Y2 on the heat pump outside seems like the issue and once connected, it does seem to produce more heat when in stage 2. I'm just curious as to how to really verify the unit outside is indeed running in stage 2...and also curious what determines the outdoor fan speed since the unit outside has a 2 speed fan - as noted in the specs. Thanks!
 
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Old 01-30-07, 04:58 PM
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About the last I can tell you is. Do you know what I mean when I say the compressor runs at the same RPM if on both stage and it justs unloads the 2nd stage .If you have a amprobe and put it on the compressor you will see a jump on it when the 2nd stage kicks in or off. The fan will also go up or down from the board. I take it you went inside the unit and took the book out. On the schermatic and how to check the unit ,


ED
 
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Old 02-03-07, 05:21 PM
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Thanks Ed. I'm just a novice here...but do enjoy understanding how mechanical things work!
 
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Old 02-04-07, 07:17 AM
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So you have a 2 stage heat pump backed up by a third stage which is a 2 stage gas furnace? No wonder it is hard to figure out. That is sort of like driving a Mercedes pulling a trailer with a BMW on it. I have trouble getting my customers to consider buying a 2 stage gas furnace let alone the heat pump. I now have the feeling I am a crappy salesman.

Sounds like your wiring change got stage 2 working. Possibly it was a bit too much for the installer to figure out.

Ken
 
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Old 02-04-07, 08:40 AM
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LOL...Ken...
Well yes it is probably a bit of overkill but I am a bit of a gadget freak...if you can call a HVAC system a "gadget". But I must say I couldn't be happier with it. In a 1961 rancher built on a slab. Old heat system had duct work in the slab and after 45 years, it had deteriorated. So moved system into attic with new insulated duct work. Sales guy tried to steer me away from heat pump because of age of house but I had the walls filled with the expanding foam insulation and thermial windows installed. Have 3 ton HP and it can maintain 73 in stage 1 and doesn't even have to run all the time to do that when it is 32 outside. Because of the longer run time for the HP, the temp throughout the house is consistent and I also don't have the "cold floor" symdrome associated with ducts in the ceiling. Balance point is set to 30. I am easily saving over $100 a month in heating / AC cost compared to the old system I replaced.
 
 

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