Line Sizes

[perrybucsdad]

Just curious. I saw this in a different thread, but never saw an answer to it and it has me wondering.

On the condenser outside, there are two lines running out of it with the cool gas and the warm gas. Why do you see reducers in the lines at times? Someone had stated that it would make the unit inefficient. If so, why do installers do it then and should I have a professional replace the lines if they are reduced in size?

[sparksandfan]

A 7/8" line uses 1.5 times as much copper as a 3/4". Installers do it because either the general contractor or the homeowner tells them that so and so will do the job for less than a realistic bid.

[perrybucsdad]

So, to make things more efficient, should I have a HVAC pro come in and upsize my lines if they have reduces in them?

[sparksandfan]

First he needs to look at your equipment and the lengths of the lines, along with some other things. Then a determination can be made as to the proper size of the lines. It's not guessing, the manufacturer has tables.

[perrybucsdad]

Okay, but I would assume that the mfg also didn't say to step down? I mean if they made a port a certain size, I would assume that is the size the line should be, not something smaller? Or am I just not understanding something?

[RyanHughes]

Sometimes smaller lines will be reused for whatever reason if they are cleaned and the line run is a short distance (i.e. 25 ft. or less). Where are these reducers that you see? Right near the unit? Are you saying that a bigger line is becoming smaller, or vice versa? A picture might help.

[perrybucsdad]

I don't have a picture, but the reducer is almost right after it comes off the unit outside. I wish I had more specifics for you, but it is a large takeoff than then gets reduced to a smaller size (don't have the specific size available at this time).

Also, the length of the run is about 40 feet.

Just from what was said before, I would think it would be more economical to run if it did not reduce.

[udarrell]

Additionally, there are times, when the compressor is at the same level or below the E-Coil, that we are required to use a suction line trap & smaller diameter riser-piping to both prevent liquid flood-back on startup & also to achieve proper oil return to the compressor. That is just one aspect off correct piping.

I wonder what percentage of installers' adhere to these important installation procedures, or correct them, when they come across a failed compressor due to faulty piping procedures. (?)

The reason most good equipment fails, is a failure to follow proper installation & setup procedures, along with inadequate duct systems (airflow) & improper refrigerant piping.

The long-life & efficient performance of all equipment is totally dependent on the total quality of of the entire system installation!
- Darrell