compressor pipe junctions and insulaltion? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: May 11, 2020, 03:08:13 am
content: I opened up an air conditioner today (indoor portable unit, I was looking to see if I can do anything to quiet it), and I noticed something. The cold part of the compressor (hot part looks like a car jack), is wrapped in some kind of insulation. Then there is like 6 inches of hose that is not insulated, then a piece of insulation thats like a foot long, then no insulation up to the condenser.Is there any reason why the full tube is not insulated? I figured it would be better in every regard, smaller thermal differentials and more efficiency. Is there a reason to leave a 'hot spot' right after the compressor and right before the condenser? I want to tape and insulate the whole thing. Is there some kind of issue with MTBF? They don't want the braze joint in some particular temperature range?condensation problems maybe? and its bent like a U, this is called a P trap I think, is there some reason to expose it partially? But anyway, the cold side, it looks retarded because they put the insulation where its like 5 inches away from the hot part (this thing gets hot), but no insulation when its like 1 inch close, so its like putting a pipe near a heater. What the fuck is this?Thermal feedback trick for regulation (thermal coupling)? Do you like tune the position of the insulation to prevent it from freezing or something? duty cycle extender? (perhaps it turns on and off too much if its not wasting cold because the compressor is too powerful?) (possibly annoying)I want to say its cut wrong or something, or just cheap, but I am paranoid about changing it.So you understand why its pissing me off : ran this unit for 5 years and it has 12 inches of ininsulated tubing in a high air flow area being blasted by hot air from the heat exchanger.

author: duak
author_rank: Super Contributor
timestamp: May 12, 2020, 09:13:10 pm
content: More 'n likely, the manufacturer is too cheap to put a longer piece of insulation in. Could the compressor get hot enough to melt the insulation? Or light off some oil?If the compressor is not at the lowest point in the refrigerant loop, I think it requires an oil trap to keep oil from backing into the heat exchangers. Could this be it?

author: coppercone2
author_rank: Super Contributor
timestamp: May 12, 2020, 10:52:11 pm
content: so you want the oil trap to be hot?honestly I see it like thisthe overlay tube is not the glued type, but its solid. so the manufacturer slides it on, not having to deal with the tape sticker or tape required to bond the insulation to the tubing. The braze would get hot enough to melt the insulation. Potentially hazardous because unless its bonded clean and uses good tape etc, it could feather off and make a high pitched annoying buzzing noise .So, the manufacturer figures out what the separation distance should be between brazed joints and the insulation, and uses that to aid in assembly ease.Hard to imagine you tune it with tubing that can slide around. I think it would be bonded if it was critical. Maybe also there was some efficiency budget in a design meeting, so someone figured out how to slash costs (the spec was too weak to survive bean counters).

author: langwadt
author_rank: Super Contributor
timestamp: May 12, 2020, 11:03:12 pm
content: from the compressor to the condenser you just what to get rid of heat, why would you isolate that?

author: coppercone2
author_rank: Super Contributor
timestamp: May 13, 2020, 01:04:27 am
content: Quote from: langwadt on May 12, 2020, 11:03:12 pmits the cold one

author: langwadt
author_rank: Super Contributor
timestamp: May 13, 2020, 09:15:23 am
content: Quote from: coppercone2 on May 13, 2020, 01:04:27 amcold is from the expansion valve to the compressor intake

author: coppercone2
author_rank: Super Contributor
timestamp: May 14, 2020, 12:10:50 am
content: Quote from: langwadt on May 13, 2020, 09:15:23 amok, I just touched it, and it already had some insulation on it. I just define it as the coolant line personally

author: langwadt
author_rank: Super Contributor
timestamp: May 14, 2020, 01:26:10 am
content: Quote from: coppercone2 on May 14, 2020, 12:10:50 amit is all coolant linespressure side is hot, suction side is cold