3 1/2 ton a/c w/2 ton coil

[dm01991]

I have a arcoaire 3 1/2 ton 12 seer ac with a 2 ton coil. My house is under 800 sq ft, Ranch. The system is just a few years old and the house cools good. The cooling costs are under $70.00 for the whole season. The inside humidity in the summer is 40-50% humid when set at 71 degrees. I realize that the condensing unit is grossly oversized for this house. What are the possible advantages/disadvantages to having such a large condensing for such a small house?

[RoBoTeq]

This sounds like an advertizing endorsement for airman1

[airworx]

oversizing outside unit will lead to compressor failures.
but since it has lasted this long without losing a compressor then i would doubt you have a 3.5 ton and 2 ton coil.i would recheck.

[klyons20]

The unit would run hard and hot.

[dm01991]

The outside unit is a 3 1/2 ton, And the coil is a 2 ton. If I check the pressure would it be in range or way out of wack because of the large condensor with the small coil?

[dm01991]

This sounds like an advertizing endorsement for airman1. What is that. Thanks for your help.

[appltech1]

Bet it has dual turbo 41 pistons for compressor equilized pull power and drag. That baby sings for 70 bucks a season.
Whow momma , I'm in love.

[Mr Bill]

Originally posted by RoBoTeq
This sounds like an advertizing endorsement for airman1

Lets not get started now, I think you ran him off already.

[skzekeman]

$70 for the year. You must be in Alaska.

[airworx]

pressures would be low suction low superheat. and a quite a few hundred dollars soon, real soon

[Black Adder]

I think someone should install the appropriate compressor on your system. I could see if you were only 1/2 ton over but you are 1.5 tons over the coil size. Compressor may not have long to live if you use it hard. What part of the country are you in and who installed this mismatched system?

[Irascible]

Originally posted by dm01991
This sounds like an advertizing endorsement for airman1. What is that.

The airman is famous for installing undersized evaporator coils. As I understand it, he'll then upgrade the coil's metering device. So if your system follows that theory you may have a 3.5 ton AC, a 3.5 ton TXV (device that controls Freon flow) and a 2 ton coil. Doing this causes the coil to get very cold and remove a lot of moisture.

Such extreme measures are only useful is super humid climates. And such measures are not approved by the manufacturers. But... if you system works as well as you say then you may want to leave it alone. Personally I'd have no qualms with trying airman's methods if I lived in an uber-humid climate. But unlike you, I have the advantage of replacing parts that go bad at cost.

[docholiday]

The coil will still have to produce superheat so it really doesnt matter which txv he chooses. 2 ton txv's will probably cover 3 tons pretty well. The nominal tonnage is closer to the middle of the travel. Oversizing it may make it hunt at low loads.

I sure hope this isnt a heat pump.

Now what will happen, is the question. A good one that I am sure Airman can address. Provided you keep the superheat set correctly you will probably produce somewhere around 2-2.5 tons with that combination, leaving more unused capcity at the compressor. I imagine the amps will be fairly low and the proper superheat should keep it cooled. Subcooling, will be high as a result. Obviously you cannot subcool below ambient. It seems the head pressure might be low and the velocity of the refrigerant low. There is a risk of load changes causing flooding at the compressor because the increased velocity through the system.

Whats the benifit? I dont see one, a 2 ton coil with 12 degrees superheat at 40 degrees saturation temp is still a 2 ton coil. If this set up makes it run at 35 degrees then you might pick up some capacity but put the system at a greater risk. You could raise the airflow slightly to increase capacity as well, thats why I say you might see 2.5 tons tops. It will certainly not be able to be charged with the charging chart or weighed in accurately but a TXV with subcooling and superheat checks may make it function.

The real problem is.... if it fails, who can you complain to? Why should a mfg warranty a system that is clearly not installed correctly?

I promise you this, if you were to call me in a technical support role and tell me your having an issue, I would say good for you, I hope it works out but if it doesnt, install a proper system and give that a whirl. The guy that installed that system is now the engineer, and the warranty department.