New Trane Unit not reaching set point

[rsamerica]

We just had a new Trane XR12 installed last week to replace our 18 year old 8 SEER Lennox unit whose fan motor seized. That old unit (prior to the motor problem) used to cool the house well and reached the set point on our digital thermostat (even if is was set <70 during the summer). Here is a day-by-day as to what we've observed.

Thursday 6/23 - Installation Day:
It ran continuously and never reached the set point of 70 (approx. 18hr., got to 76-77). Outside temp. 80.

Friday 6/24:
Had the installer come back out, and we noticed water underneath the unit and they claimed it had likely frozen up. Ok. Turned off the unit, and checked the freon and overall it seemed fine. We had to leave for the weekend, so we turned back on and set at 75. Outside temp 85.

Sat. 6/25 - Sun 6/26: Outside temp >90.

Last night 6/26:
Returned home after weekend and thermostat reading 80. Outside temp. 83. Water again under unit. Turned unit off for 4-6hr. Turned back on for night with a set of 74. Woke up in the morning and it was at 74 - amazing.

Today 6/27:
Temp. set to 73 and it reached 73 by 9:00am. By 12pm, temp outside was 85 and temp inside set to 73. At 3:00pm, thermostat reading 77. Now its reading 78 with unit off. I'm giving it a few hours to settle and will turn back on, set to 75 to see what happens.

It appears the set point is rarely reached with this new system and I am not sure why. Also, there is continually a medium amound of water creeping out from under the unit. The installer is going to come back out Friday to check again, but I am curious to know why a brand new, much more efficient unit is having a hard time bringing the temp down to the set point. Any thoughts?

Thanks.

[BaldLoonie]

Same size as old Lennox? Replaced unit, lines & coil so all is new? Nothing reused? Not sure what is going on. If old components were reused, could affect performance.

[Irishmist]

The contractor probably won't like this, but, there should have been a load calculation performed before the 'new' system was recommended and installed. also should have checked the air distribution system to be sure there were no underlying problems. With the higher efficiency equipment, airflow is even more critical, so even if an older system was 'operating' a new one may have problems.

Water only occurs one of two ways: condensate leaking from pan or from drainline, or indoor coil freezing up and then thawing.

Was there ever a determination made whether or not the coil was freezing up? If this happens you will see a LOT of water, not just a little. I am assuming you are referring to the indoor equipment?

That first day it should (after running that amount of time) have satisfied the setting on the thermostat. Especially at an 80 degree day (not all that hot!) Ask for the service manager fromthe company to come out and inspect the job, just to get another opinion. May be a problem with the metering device, etc. or some other mechanical problem.

If the coil is in fact freezing up, then your airflow will actually diminish to zero, since it can't move air through a block of ice! Again, once this thawed, you woudl have major water around the base of the furnace.

Insist on a load calculation. This should have been done at first, but better late than never. If they still can't diagnose and correct the problem, as for a factory rep. to come on site, BUT, give the contractor a fair chance to correct the problem. He shouldn't just throw up his hands, and say "beats me." That is no good for you.

Good luck.

[travisfl]

Originally posted by rsamerica
We just had a new Trane XR12 installed last week to replace our 18 year old 8 SEER Lennox unit whose fan motor seized.

What was replaced, just the condenser (outside unit) or the condenser and the air handler (inside unit)? Is the puddle of water under the air handler or the condenser?

[techlarry]

Sounds exactly what I've been going through...

-Larry

[Panama]

rsamerica,

Please describe what was replaced and give us the model numbers of all the new equipment. Also, did they install a TXV (or TEV)?

What worries me is that you say the installer turned the AC off to check the Freon level. Checking and adjusting the Freon level properly takes an hour or so, during which the system must be running. If the indoor coil is frozen it must first be thawed.

[rsamerica]

Thanks all for your quick replies. Some answers and clarifications:

1. Only a new condensor unit was replaced. Still have same air handling system inside.

2. Water is coming out from under outside condensor (one the concrete slab on which it rests). Appears on right side, front primarily. A small amount right side, rear (where removable panel is).

3. A load calculation was not done, to my knowledge.

4. Model: Trane XR12

5. Installer had unit running when checking freon. He did mention that once it was running, the "preloaded" freon was not enough to "fill" to where it should be, so more was added.

Does this information help?
Thanks.

[rsamerica]

Two more quick things:

- In April, I had the same company who installed the new unit come to the house to inspect the original unit. New filter installed and they said everything looked good. Of course two months later, the fan motor seized....

- I did not have a filter on the freon line with the old unit. When the new unit was installed, they also added a soup-can sized filter to the freon line. Would this do anything related to the problems I'm seeing?

Thanks again.

[rsamerica]

Lastly, the old unit was a 2 ton unit and so is the new one.

[travisfl]

Did they replace any parts in the air handler, such as the coil or a valve (specifically, a piston or thermal expansion valve)?

[rsamerica]

Nothing other than the condensor was replaced/changed.

We have a 2 floor 2100 sq. ft. condo with the thermostat upstairs. The basement is cold, probably below at (or possibly below) set point. That was the case with the old unit, too, but the thermostat upstairs used to reach the set point. Now it doesn't with the new unit.

[BaldLoonie]

When you hack a 12 SEER outdoor unit on some old indoor system, you could have operational difficulties and reduced capacity. The 12 SEER runs much less head pressure and requires an expansion valve indoor meter. If you have a fixed meter and/or a small evap designed for low SEER, you could be low on capacity. This is what happens with a poorly done job. The proper Trane TXC coil with expansion valve should be installed.

[travisfl]

Originally posted by rsamerica
We just had a new Trane XR12 installed last week to replace our 18 year old 8 SEER Lennox unit whose fan motor seized.

Please confirm this an R22 condenser. The model number starts with 2TTR.

[rsamerica]

Yes, this is an R22 version. I will check with the installer when they return this week regarding installing a new coil to handle the 12 SEER compressor. I had another installer for an estimate, and he, too, said that the inside unit should be fine for a 10-12 SEER unit. Anything over 12 would need a new coil. This was based on both of these contractors' previous experience in our condo complex units (all had same Lennox products when built in 1986).

[travisfl]

First, they need to do a "Manual J" heat gain / loss calculation to make sure that 2.0 ton is sized right for your condo. Assuming that it is, then have them install a matched coil with a TXV (thermal expansion valve), making sure that there isn't any room around the sides of the new coil for air to bypass it.

[Edited by travisfl on 06-27-2005 at 06:19 PM]

[rsamerica]

What is the significance/source of the water I'm finding seeping out (slowly) from under the outside compressor?

[mark beiser]

You say you live in a condo.
Is the indoor unit an air handler in the cieling, like over a bathtub, or in a hall?

If so, there is no way that air handler is the least bit compatable with a 12 SEER outdoor unit. Most of the time 10 SEER outdoor units barely work something like acceptably with them.

You need to replace your indoor unit for the system to work correctly. With the age of the system, it is about time for it anyway.

[rsamerica]

The air handler is in the lower level, with one intake vent on each floor (one is in one of the walls in our front foyer(upstairs/ground-level) ; the other is in one of the walls to the small room where the air handler/furnace is located in the lower level). The filter is new.

[dnt]

I think the key here is that water is seeping out of the new condensing coil unit the poster has mentioned that at least twice and he is correct that it is unusual and indicates a problem. This would indicate that saturated liquid is being returned to the condensing unit and suction line and compressor are sweating profusely. Severe Overcharge most likely. The condensor can be made to work but a proper superheat and subcooling has to be done to adjust the charge level to work with the system as it is set up, do not run the unit untill the charge level has been set correctly. If you want 12 SEER performance change out the evaporator for a matched coil, this setup that you have will be very inefficient. It can be made to cool though with a bit of tweaking. You may have to call the owner of the company you are dealing with and explain the mismatched coil situation, and that you want someone to check the charge level and set it up using the superheat/subcooling method, hopefuly he has at least one guy that can do that.

[rsamerica]

Interesting point, DNT. Let me elaborate. When they installed the condensor on Thursday, the technician said that he was surprised to find that the "precharged" amount of freon in the new unit was not enough to "fill" the system and that he had to add more to get the proper gauge readings. He used a tank (which was apparantly almost empty as he had to shake/turn upside down/etc. the tank to get a proper reading from the system). When the technician and one of the service managers came back the next morning after my phone call to them regarding the cooling problem, they checked the readings and although they appeared fine, they used a second tank to put more freon in. The manager said that "he knows how much can go in" without causing problems... I guess the point is that the problem with the water was occurring even after the first day when the technician installed the unit, so perhaps it was even overcharged at that point?