Condenser lines length

I installed two 5 ton split system AC's on the roof of an 8 story building that had a KFC kitchen in the basement and the dining area on the first floor. The longest run was approximately 100' so I upsized the lines one size larger than normal. I installed 2 oil trap in the suction risers, one at the bottom and the other at the mid-point. I installed accumulators in the suction line at the high side on each unit.

Everything worked well except the one thing I didn't upsize. I used 18 ga. control wire out of habit and it wouldn't reliably pull in the unit contactors. I repulled #12 wires and all was well. That was in 1984 and the store made it out of warranty and may be still running those units AFAIK.

That's not the longest refer lines I have run but it was the highest. It ran down from the roof alongside the fire escape ladder which made the sil-phos brazing the joints possible once I quit shaking. That building was the former Lankershim Hotel and at least 80 years old, so the fire escape ladder didn't look all that healthy. It's located near the corner of 7th & Broadway in downtown Los Angeles. I think I'll take a look with Google Earth and see if it's still going strong.

Line size at long distances and/or with long risers do require upsizing on occasion but when you do that you are lowering the gas velocity and must address how you get the oil returned to the compressor. Slope is important on horizontal runs but not always possible. It is also important to add additional oil in very long runs. Of course you will need to add additional refrigerant if installing a precharged system.

On other long run systems with multiple pump-down evaporators, we used oil separators since the gas velocity often went so low that the crankcase oil level would go too low if steps weren't taken to prevent it.

If you must err, do it one the side of under sizing the run slightly... it's less risky from a compressor damaging standpoint.

Holy guacamole! Looks like they're parking cars on that roof now!! The rusty looking rectangle you see there is the metal roof that covered the units I installed. Time has changed things considerably. Parking lot lights also!

The location indicator isn't correctly placed as usual with Google.
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I'm going to bore you even further now. When I installed those AC units in 1984, it wasn't the first time I had been in that building. I stayed in it when it was the Lankershim Hotel and still pretty up scale. That was in 1960 when I was shotgun driver on a 18 wheeler Mack B-61 and a 60' Dorsey refrigerated trailer that my brother and I owned. We stayed there every trip from back east while waiting for our broker to get us a load for the return trip. Usually we hauled ice packed chicken out and oranges, lemons or lettuce back.

Talk about your strange turn of events! It was de javu that second time around but the building was in serious decline at that time and there were so many bums sleeping in the alley behind that it took real care getting our construction trucks through each morning to park without running over one of them. We had to hire a security guard after having the trucks get broken into a few times.

If you're still awake, thanks for reading. If you didn't find it worthwhile, that's OK... I wanted to hear it again. :vs_laugh: