trane xl1400 circa 2003

[paschal_old]

Too muddy near the unit with all of the recent rain to get the outside model number. If absolutely needed, I'll get the rubber boots down.

 

This is total electric home. Unit has two heat strips installed with twin 60 amp breaker for power and of course the fifty for outside.

 

I started noticing a couple of months ago strange behaviour such as long cycles and temps that seemed too high....mid 30's for backup to kick in. I noticed that by turning off and flipping breakers for an hour or so it seemed to behave ok for a day or two, but that would not be enough info to post about.

 

Found a digital thermometer, hung it at an outlet about 20 feet from the air handler, and then it got interesting. normally use the hold temp setting on the thermostat at 69 degrees in the winter. After running errands for a few hours with breakers off, temp in house falls to 65. Kick breakers back in, backup kicks in and air temp goes as high as 111 degrees. Cycle time about 40 minutes to get back to 69. In maintain mode air temp only gets to 78-79 which seems low. Outdoor air temp 45-50 degrees through the day. Last night temp only went down to about 41. When I got up this morning unit is in contiuous cycle and blowing about 72 degrees. Bumped thermostat to 70 backup kicks in and cycles, then back off to 69 again, now cycling on and off with air temp about 79 degrees. Indoor coil has never been cleaned, but just read suggestions here on how to. Cleaned outdoor last summer. My guesses are freezing due to low freon, dirty coil, defroster problem, or most likely what would be suggested. Unit is still under parts warranty, but not labor. The unit has an indoor logic board, I guess for the variable speed control.

 

 Last year, I had the variable speed outdoor motor replaced under warranty. It died because the drop in motor mount had a brokem arm due to bad spot weld. The HVAC company tried to tell me it was not under warranty, so rather that prolong the fight I had it quality welded at all arm points then painted it with that spray paint made for weld joints to protect it from rust.

 

I wish I had run air temp tests when the unit was new to know what normal for me should be. I have heard mid eighties should be normal for a heat pump.

 

responses greatly appreciated as it took a long time to write all of this history!

[dkpd1581]

Make sure the indoor filter and coil is clean.  With the outdoor coil defrosted, run the unit without the strip heater and get a temperature rise at the indoor unit (temp in/temp out).  Note the outdoor temp and get back with us....you could possibly have a low charge, broken duct work, poor insulation.  Also let us know the charge R22 or R410A along with the model number and then we can check the IOM for the temp rise you should be expecting.

[paschal_old]

will do, the rain is moving out later today. In the meantime, it is r22, the ductwork is flex r-8, and with the exeption of one room, the air flow is very good. The unit is dead center downstairs of a round two story house of the extreme insulated variety 6 inch walls, with r-19 plus r5 foam board. There is a seconday boot structure dead center in the attic upstairs. r-30 bottom layer insulation with r-19 covering ductwork where possible on top. Mastic and metal tape etc seemed to have been properly installed. I built most of the house by hand, so pretty aware of what is what. Dampers also in use for seasonal adjustment which seem to adjust airflow ok. As for filters, I change at least every other month and use 20x25x1 accordian type.

That should cover all but needed model nums. I'll get them later today and post photo for the air handler side for help with coil access.

No reply needed until I get that mod number, just thought I would give the rest of the background.

[paschal_old]

Model is TWY048B100140 SERIAL R061TMA1F. This is from an invoice I found from the motor replacement.

I know, I am just trying to stay out of the mud

The air handler stack is shown as TWE065E130A1 WITH SERIAL M1321WN1V. Shown as 1 HP. I pulled that from the unit itself.

The thermostat says Honeywell Chronotherm III.

I'll throw this in as well....The proposal did not quite agree on model nums. Will furnish on request. It showed 49,000

btu cool and 43,500 heat, variable cfm.

I failed to mention the return placement. One is next to the air handler, less than a couple feet away. Goes to a platform on the floor under the filter insert. The other is near the attic boot just below the ceiling upstairs. They are both large. I switched to the pleated filters during the second year. I am concerned that it was installed with a spun glass cheapo, and I was dumb enough to use the box of them they left behind, so the coil does concern me. but that was 2003 when the unit was fired up.

The outdoor supply lines are in rubber pipe wrap.

All registers are in the ceiling. Hopefully this will give you enough to work with

[applianceman18007260692]

Seems to me you have a problema with the defrost board.

[paschal_old]

I have been leaning to a defrost issue or low charge. As mentioned my biggest mistake was not knowing what is normal from a couple years ago.  Right now in the mid sixties and it blows at 74.5 degrees.

Does the fact that this is a variable speed motor affect the output heat temp?

BTW the house is about 2800 sq ft but super insulated.

[applianceman18007260692]

It probably ain't a low charge. I doubt a variable speed would effect it unless you had a dirty A-coil.

[dkpd1581]

If you have a 60F ambient and you are only getting 74.5 then you have a charge issue.  Your variable speed motor will either modulate based on static pressure or via a pre-programmed speed set by the manufacturer (configured via dip switches on a control board).

A clogged coil will cause a build up of heat due to low air flow and give you a higher supply air temp.  A defective motor engaging in a too high of a speed will give you a lower air temp than desired but not to the low level of 74.5F.

I would check the outdoor coil to make sure its clean, no obstructions to the sides or overhead, then I would look to the charge, if it continues with an otherwise clean non frosted coil then I would look to the reversing valve.