A friend just had a new Trane AC system installed in his condo yesterday to replace a 20+ year old system. (The furnace, also a Trane, was replaced about three or four years ago.) The new equipment is:
Trane, M- 4TTM3036A1000C, 3 ton 410A refrigerant air conditioning condenser
Trane, M-4TXCB036BC3HCB 3 ton evaporator coil
These are Trane's bottom-of-the-line units, XB300 condenser. (It was the only one that would fit in the space he had for it behind the building.)
My friend's unit is 1100 square feet, and takes up the entire third floor, with only windows front and back (as he is sandwiched between adjacent buildings). The furnace closet is toward the front of his unit, and the condenser is in the back, at the ground level. I would guesstimate that the 3/8-inch liquid line goes up 30 feet to get to the third floor and then another 50 feet inside the unit to get to the coil above the furnace.
According to the installer, he is getting an 11.5 degree drop in temperature, comparing the intake air to the air just above the coil. In the next room, he is only seeing a 10 degree drop. The apartment temperature at the air intake was about 70 degrees, and the temp above the coil was 58.5 degrees. I do not know the humidity.... but this is Boston, and yesterday and today have not been dry.
My sense is that this small a drop is unacceptable, causing the unit to run several hours, just to drop the temperature 2 or 3 degrees. When we questioned the installer about why we were not getting a 20-degree drop, he passed that off as no longer a good rule of thumb.
I dug around online to find the installation instructions for the XB300. It included this table about adding more refrigerant when the unit was more than 15 feet from the coil:
![Image]()
This seems to say (remember I am a lay consumer) that for runs of 80 feet for a 3/8" liquid line, the installer should add 2.6 pounds of refrigerant. The installer added only 3 ounces.
The installer and his boss were adamant that they did it right, based on NEW installation instructions from Trane, and talking to Trane. The new method only involves measuring pressure (and temp) and not taking into account distance directly at all.
![Image]()
What seems illogical to me is that the old method to figure amounts of refrigerant called for 2.6 extra POUNDS (based on distance), but the new method (based on pressure) supposedly yielded a requirement of only adding 3 ounces to get to the right pressure. Both installation instruction methods are for the SAME condenser.
This is all Greek to me... but it seems like my friend has a genuine problem, with only a 10 or 11 degree drop in output air temperature. (By contrast my older Trane in a different housing situation, outputs 48 degree air with an intake temperature of about 73 degrees.)
Trane is absolutely useless in terms of consumer inquiries -- they told my friend they provide no direct customer support to end-user consumers.
So I turn to you all! What advice can you offer?
Thanks in advance,
Edgar
Trane, M- 4TTM3036A1000C, 3 ton 410A refrigerant air conditioning condenser
Trane, M-4TXCB036BC3HCB 3 ton evaporator coil
These are Trane's bottom-of-the-line units, XB300 condenser. (It was the only one that would fit in the space he had for it behind the building.)
My friend's unit is 1100 square feet, and takes up the entire third floor, with only windows front and back (as he is sandwiched between adjacent buildings). The furnace closet is toward the front of his unit, and the condenser is in the back, at the ground level. I would guesstimate that the 3/8-inch liquid line goes up 30 feet to get to the third floor and then another 50 feet inside the unit to get to the coil above the furnace.
According to the installer, he is getting an 11.5 degree drop in temperature, comparing the intake air to the air just above the coil. In the next room, he is only seeing a 10 degree drop. The apartment temperature at the air intake was about 70 degrees, and the temp above the coil was 58.5 degrees. I do not know the humidity.... but this is Boston, and yesterday and today have not been dry.
My sense is that this small a drop is unacceptable, causing the unit to run several hours, just to drop the temperature 2 or 3 degrees. When we questioned the installer about why we were not getting a 20-degree drop, he passed that off as no longer a good rule of thumb.
I dug around online to find the installation instructions for the XB300. It included this table about adding more refrigerant when the unit was more than 15 feet from the coil:
This seems to say (remember I am a lay consumer) that for runs of 80 feet for a 3/8" liquid line, the installer should add 2.6 pounds of refrigerant. The installer added only 3 ounces.
The installer and his boss were adamant that they did it right, based on NEW installation instructions from Trane, and talking to Trane. The new method only involves measuring pressure (and temp) and not taking into account distance directly at all.
What seems illogical to me is that the old method to figure amounts of refrigerant called for 2.6 extra POUNDS (based on distance), but the new method (based on pressure) supposedly yielded a requirement of only adding 3 ounces to get to the right pressure. Both installation instruction methods are for the SAME condenser.
This is all Greek to me... but it seems like my friend has a genuine problem, with only a 10 or 11 degree drop in output air temperature. (By contrast my older Trane in a different housing situation, outputs 48 degree air with an intake temperature of about 73 degrees.)
Trane is absolutely useless in terms of consumer inquiries -- they told my friend they provide no direct customer support to end-user consumers.
So I turn to you all! What advice can you offer?
Thanks in advance,
Edgar
