View Full Version : PLZ help O/S Trane system
07-08-2006, 06:15 PM
New Trane XL14i 5 ton heat pump with TWE065 AH installed in 04. Since day one unit has short cycled 5 min. on 6-7 off...I knew it was not right but installed insisted unit is right.My humidity was in the 60-70 % range. Calculation called for 4.3 ton and they said with a heat pump I needed a 5 ton. Finally after much arguring they came and ran an 8" pipe from the attic to the return box. This to me was dumb but it increased my run time to 10-12 mins. and humidity has dropped to 45-53%. I installed a robertshaw 9870i that has a dehunidification relay built in that I want to use. Which terminal in the LVTB will this go to? Also since I have a HP the O to Y jumper is not needed? What does YLO terminal do? I want to use the new T'stat and hopefully get a 15 min run time and RH down to low to mid 40's. The installed will not admit the unit is oversized but I know beyond a doubt it is, and want to try to correct it myself due to them being A holes. I have read thousands of topics and Trane wiring seems to be scarce...
Thanks a bunch
07-08-2006, 06:25 PM
If you had a load calculation that called for 4.3, then you got the right unit. Unfortunately the sizing on residential units goes from 4 to 5. no 4.5 ton. 0.7 oversized is no cause for alarm. I'm sure most guys would have done the same thing.
07-08-2006, 08:56 PM
I would have went with a 4 ton with that calculation. I would suggest finding another hvac guy in your area to help with the wiring.
07-08-2006, 09:03 PM
Trane wiring for your LTVB is scarce because Trane will not warranty a DIY job. This is Trane's way of ensuring only a licensed contractor works on your equipment. If you are ubsure of what you are doing after reading the install manual that came with your equipment, then call a licensed contractor. Trane will be happy to recommend one in your area.
07-08-2006, 11:22 PM
That equipment matchup wouldn't have been an option I would considder for a house with a 4.3 ton load.
Prefereably a 4 ton heat pump and some added insulation to reduce the heat gain of the house.
Another option would have been the 5 ton heat pump with a TWE049E13 air handler and the airflow set to 1750 CFM. It would drop the sensable capacity down a lot and raise the latent capacity of the system.
It lowers the SEER of the system, but increases comfort dramatically. These are "comfort systems" afterall...
To use the dehumidification function, remove the jumper between R and BK on the LVTB. Wire the dehumidification terminal of the thermostat to BK.
If there really is an 8" duct sucking air directly from your attic into the return of the system, that needs to be removed, or ducted to a return grill. The person who came up with that idea also needs to be drummed out of the industry and find a job he is more qualified for, like monitoring the french fries at McDonalds.
It sounds to me like you need to have an actual qualified contractor come out and evaluate the system, have them wire up the dehumidification function of your thermostat while they are at it.
07-09-2006, 06:49 AM
Yes the 8" pulls out of the attic, it has a screen on the duct and the filter in the bottom of the AH catches the rest. The next closest is about 90 miles. I KNOW the issues with DIY stuff and feel that I am probably more skilled than some of the "installers / contractors" out there. I've tried talking to techs, with no resolutions. I figured the disconnected BK terminal when not energized cuts the blower to 80% then back up when energized, and I figure the Ylo is for a 2 stage compressor. But even with this BK hooked up to DH relay( with a 1 amp fuse just in case), the VAH set to 350 CFM/T, I still cant get a good 15 min run time with Comfort R set on. ALL I want is my electric bill to drop a little (from short cycling), a low humidity house for family (allergies), the longest life out of the system, and the system to run at peak performace.
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