I am in there process of replacing my 5 ton air conditioning unit. One of the contractors told me that my refrigeration line going into my outside unit is the incorrect size. He said I have a 7/8" line and this unit requires a 1 1/8" refrigeration line. What is the correct size of the refrigeration line I need for a 5 ton air conditioning unit?

What did the other contractors say? In some instances the suction line size needs to be increased, however, 7/8 will work, but you will loose efficiency with the 7/8(dont think it would amount to much). Lets see what HVAC1000 has to say about it. Is this a residential ac unit?

Without knowing all the exact details it is difficult to be accurate. Under normal circumstances a 7/8th's OD copper line would service a 5 ton unit BUT with the advent of today's high efficiency units it is a good possibility that your new system needs a 1 1/8th OD copper line. One thing you never want to do is cheat on the suction line sizing since the suction line provides the essential return of cool gas and system oil to keep the compressor motor windings from overheating along with controlling the precious compressor's oil temperature so there is less varnish breakdown on the motor windings over the life of the unit. To small of a suction line can shorten the compressor/units life expectancy.

In the install manual for the unit it usually gives a distance and height requirements for the system supply and return copper line sizes to operate properly. They need to be followed exactly. There is much more to the suction line sizing than posted here especially when it comes to suction traps etc but the information posted will get you going in the correct direction.

How far is the line (how many feet) to the evaporater coil? Also what is the size at the connection of the condenser and at the evaporater?, if its 7/8, 1 inch, or whatever that is the size lineset you need,, unless its more than 50 feet distance that will make a difference

Size of the fitting on the evaporator or condenser does not indicate correct line sizing. This is a common mistake in the trade. Now I will say under most circumstances you can get by with that size BUT you need to calculate lift,length, size,velocity,refrigerant type,just to name a few. These calculations are normally done by the manufacturer and included in the install instructions as the appropriate size for a given length so you do not have to do the math.

what did the other contractors say? In some instances the suction line size needs to be increased, however, 7/8 will work, but you will loose efficiency with the 7/8(dont think it would amount to much). lets see what HVAC1000 has to say about it. Is this a residential ac unit?

This is a residential AC unit. The other contractors did not say anything about the 7/8" line being too small. Thanks for your response.

Without knowing all the exact details it is difficult to be accurate. Under normal circumstances a 7/8th's OD copper line would service a 5 ton unit BUT with the advent of today’s high efficiency units it is a good possibility that your new system needs a 1 1/8th OD copper line. One thing you never want to do is cheat on the suction line sizing since the suction line provides the essential return of cool gas and system oil to keep the compressor motor windings from overheating along with controlling the precious compressor's oil temperature so there is less varnish breakdown on the motor windings over the life of the unit. To small of a suction line can shorten the compressor/units life expectancy.

In the install manual for the unit it usually gives a distance and height requirements for the system supply and return copper line sizes to operate properly. They need to be followed exactly. There is much more to the suction line sizing than posted here especially when it comes to suction traps etc but the information posted will get you going in the correct direction.

Thank you for your input. I will research the installation manual.

Hi Dear
I am a hvac tech,I need your help to make a small absorption chiller about 5 ton for my house.Beacuse I am a technicion so I don't have good thiury,So dear can you Advoice me how I can calculate the air cooled condenser, evaporator,genrator and the quantity of amunia with water sulotion. I hope you will send me useful informations
Thanking with best regards

Before you guys get to deep into this question, NOTICE the question was published over 2 years ago

Don't worry wmproop. I wouldn't touch this one with a ten foot pole. A little beyond my expertise.