Cost, loss of velocity and voiding of the vendors warranty... Why would you be looking at an over sized line? In nearly all cases it's the other way around (a.k.a. changing from R22 to R410a) Please give the other factors in your particular situation so that a meaningful answer can be attempted. Are you feeding a TXV or a fixed metering system? Height and length of the run? etc.

 

Just trying to understand what the problems would be with an oversized line? Create your own scenario and explain the possible problems. As you mentioned "Txv or Fixed" would the potential problems differ for each system and what would they be? Please explain?

 

Oversized Liquid Line

Probably the most common operational problem would be the system charge required to fill the line.

System and component design dictate the amount of total charge that can be safely managed in any given system.

When those limits are exceeded various components such as liquid line solenoids,crankcase heaters,and accumulators to name a few.

There is nothing to be gained by using a large liquid line.

 

Re: Oversized Liquid Line

Probably the most common operational problem would be the system charge required to fill the line.

System and component design dictate the amount of total charge that can be safely managed in any given system.

When those limits are exceeded various components such as liquid line solenoids,crankcase heaters,and accumulators to name a few.

There is nothing to be gained by using a large liquid line.

Spot on information.

Over sizing the liquid line requires excessive charge to fill the liquid line with liquid refrigerant. If you don’t fill the line up completely it won’t completely meter all the refrigerant.

Suction lines can be increased to maintain capacity on long runs. The suction line is full of gas and gas will expand to the diameter of the pipe.

When you start getting close to about 4lbs of refrigerant per ton start preparing for a compressor change out.

 

If its a heat pump you can count on charge imbalance problems from season to season. I dont think there are any, if at all legitimate reasons to oversize the liquid line and then complain of poor performance or reliability of a unit. mfg's go through great pains to develop and test the tables and since they did that, it would be best to heed the tables and consider them accurate, there is no + or -.