trane xl16i 2 stage, high humidity

[beenthere]

Just to help the OP understand. Your video shows a duel fuel setup where the heat pump coil is on the bottom (upflow) and you can see the p-trap that was installed. The upper drain connection (that uses the tee fitting) is for condensate from the high efficiency furnace which has its own internal trap. From his description its sounds like he has an ac coil on top of furnace and that the AC coil drain uses a 'tee' fitting. Just guessing.

Upflow furnace with the coil on the return?

Improper install.

[bobl]

Update: thanks to the excellent replies on this thread. Absolutely useful and great education for me and hopefully helpful to others in future.

Root cause found to be crossed wiring at outdoor unit. Tstat was signaling for compressor to run at low and turning fan to low. However, outdoor unit was not coming on until tstat signaled for high.

Now at 42% to 45% humidity. Doesn't come on very often, when it does it's on low - very gentle air flow. No problem hold temp at 78 at 100+ outside. No sticking to floors.

One observation: when the unit was running the fan w/o compressor we noticed that our normally blast furnace like upstairs was almost same temp as down stairs. It was dramatic change. This tells me that the classic upstairs/downstairs problem might be solved with a more continuous air flow. However, it would have to be done without humidity. It will take a few days to see how things are now that unit is working correctly.

I asked about comfort-r setting, tech said he didn't set it. He wanted to try things without it.

One last question - thanks for indulging me.

What the heck is comfort-r exactly? When unit is in comfort-r what does it do that is different than when it is not in comfort-r?

[freonr22]

You should have air streaming out of only your supply outlets. Air should be streaming in only through your return grilles.

I didn't see any model numbers so I've got make some assumptions but the variable speed blower can be set for several different configurations. You need to have someone knowledgeable from the installing company pay a visit and set up and/or confirm that the blower is set as follows:

1. Airflow set for a 4-ton system.
2. Airflow set for 350 CFM/ton
3. Comfort 'R' mode selected 'On'.

It's very likely that no matter which stage the outdoor unit is using, the airflow for the system is set too high. The variables are 3.5-5.0 tons, (yours is 4.0-tons) and from 350 to 450 CFM (Cubic Feet Per Minute). The faster the airflow, the less dehumidification you'll get. Comfort 'R' is a Trane patented method of enhancing 'short cycles' by restricting blower operation to 50% of full speed for 1-minute (slow airflow to allow the indoor coil to cool faster) followed by 7-1/2 minutes of 80% of airflow. That's all to assist in greater moisture removal than would otherwise happen.

Very detailed responses... nice!

[bobl]

Ack! I read that earlier and then completely pushed it out of my brain.

Perfect description. Thanks Skippedover and freon22.

[mayguy]

Get the Comfort-R turned on. That will get the coil colder, and help with the humidity control.

[catmanacman]

I always turn on the comfort r on the 16 I

[bobl]

Thanks very much for the replies - the tech didn't set comfort-r. The unit is running really well right now. Austin has lower humidity than most place in south, but right now it is like 102 to 105F outside so maybe its the heat not the humidity for a change!

You can read about our results with the unit here. We are so impressed right now, and it is one of those rare times things work better than you hope, I am afraid to mess with it!

http://hvac-talk.com/vbb/showthread.php?t=894702&page=2

My experience seems to show that two stage can work well even in hotter than h#ll Texas. Hope this technology comes down in price.

[lynn comstock]

I don't know why Comfort R is not the default setting on those variable speed air handlers. It should be. IMO.