Insulating Refrigeration Lines

[mikeo16]

Hi, I am installing a new BD50 refrigeration system. Questions: there are 2 copper lines (1/8" and 5/16") that run about 3-4 feet from the compressor to the icebox. I was going to wrap the two lines together with rubber pipe insulation. Or is it better to insulate each line separately? what is the typical difference in temperature between the 2 copper lines? Is the rubber pipe insulation the best (at Home Depot, they have an R-value of 3.3) or is there something better recommended? I have plenty of access in and around to these lines and it is a straight run.

[SV THIRD DAY]

Originally Posted by mikeo16

Hi, I am installing a new BD50 refrigeration system. Questions: there are 2 copper lines (1/8" and 5/16") that run about 3-4 feet from the compressor to the icebox. I was going to wrap the two lines together with rubber pipe insulation. Or is it better to insulate each line separately? what is the typical difference in temperature between the 2 copper lines? Is the rubber pipe insulation the best (at Home Depot, they have an R-value of 3.3) or is there something better recommended? I have plenty of access in and around to these lines and it is a straight run.

The R value of what you put around the tubes doesn't matter. From a system operation standpoint the lines technically don't need to be insulated, BUT I always recommend putting the black split how water insulation you get from home depot around the two lines together to Protect Them. You don't want something smashing up against them in rough seas and either rupturing the lines or smashing them and restricting the flow.

[deluxe68]

Get the stuff from an A/C supply shop, and get some tape to wrap around it. The insulation will make your fridge a tiny bit more efficient, but more importantly, if you wrap it with the correct tape properly you will keep the cold pipe from contact by humid air. Do not use one piece of insulation to wrap around both tubes at the same time. Also, make sure the size of the insulation matches the tubing diameter.

[mikeo16]

thanks SV Third Day - yes, the area where the tubes will be running is all by itself with no loose gear to bump into it. I will also add supports so that the lines will not be freely hanging.

Deluxe68 - both you & Rich are in agreement that there is not a lot of cold lost but maybe a little. If I am reading your response correctly, you are suggesting the two lines be independently insulated? is that correct? My only concern is that the 1/8 inch line is so skinny it would be difficult to find insulation for that size

[travellerw]

When my lines were not wrapped, one of them constantly dripped condensation water. This eventualy led to mold forming where the dripping was happening.

I insulated them separately with foam insulation I got from a refrigeration place. Dripping problem was solved after that. I think I paid $6 euro for 2 meters of it.

[deluxe68]

Originally Posted by mikeo16

thanks SV Third Day - yes, the area where the tubes will be running is all by itself with no loose gear to bump into it. I will also add supports so that the lines will not be freely hanging.

Deluxe68 - both you & Rich are in agreement that there is not a lot of cold lost but maybe a little. If I am reading your response correctly, you are suggesting the two lines be independently insulated? is that correct? My only concern is that the 1/8 inch line is so skinny it would be difficult to find insulation for that size

Look at it this way, the refrigerant going into the fridge is going to be cold, when it comes out of the fridge it will be warm/hot. If you wrap both lines (touching each other) with the same insulation, you are going to warm up the cold refrigerant going into the fridge. Also, I looked up the Danfoss web site and it looks like your lines are 3/16 (5mm) and 1/4 (6.2mm), there is insulation down to 1/4.

Here is a link that might explain it better.

https://inspectapedia.com/aircond/Re...Insulation.php

And here is one type of tape I have used.

https://www.globalindustrial.com/p/p...ide30-per-roll

[mikeo16]

thanks Deluxe68 - excellent information - greatly appreciated

[newhaul]

Personally I would insulate both together as suggested by SV third day if for no other reason than he has been building refrigeration systems for boats for 50 years. So likely knows what he is talking bp about.

[SV THIRD DAY]

Sometimes out of repetition I shorten up answers, but the reason you would like to put both lines together is that the warmer supply line will help keep condensation from flowing on the cooler return line. Now if you have serious line sweating and even frost on your return line, then you are most likely overcharged...on a Craptube system.

As for Newhaul's comment about me knowing what I'm talking about....my wife just spit out her drink laughing!
Luke 4:24
And he said, Verily I say unto you, No prophet is accepted in his own country.

[newhaul]

Originally Posted by SV THIRD DAY

Sometimes out of repetition I shorten up answers, but the reason you would like to put both lines together is that the warmer supply line will help keep condensation from flowing on the cooler return line. Now if you have serious line sweating and even frost on your return line, then you are most likely overcharged...on a Craptube system.

As for Newhaul's comment about me knowing what I'm talking about....my wife just spit out her drink laughing!
Luke 4:24
And he said, Verily I say unto you, No prophet is accepted in his own country.

where are you and where am I ? Different countries
Btw glad I could make her day.

[a64pilot]

Originally Posted by deluxe68

Look at it this way, the refrigerant going into the fridge is going to be cold, when it comes out of the fridge it will be warm/hot. If you wrap both lines (touching each other) with the same insulation, you are going to warm up the cold refrigerant going into the fridge. Also, I looked up the Danfoss web site and it looks like your lines are 3/16 (5mm) and 1/4 (6.2mm), there is insulation down to 1/4.



Here is a link that might explain it better.



https://inspectapedia.com/aircond/Re...Insulation.php



And here is one type of tape I have used.



https://www.globalindustrial.com/p/p...ide30-per-roll

It’s actually the other way around, the high pressure line will be warm, and due to phase change and thermal expansion the low pressure one will be cold.
High pressure to the evaporator, then low from the evaporator.
However as far as increasing efficiency, I doubt it. Your cooling the high pressure side (good), but heating the low pressure side (bad).

I believe from a pure efficiency side, you want to insulate the low pressure side by itself, look at a home system and see how it’s done there.
However Rich’s point of protecting the lines is likely more valid than any slight efficiency increase, and also probably eliminates sweating.

[missourisailor]

Way back when I was in HVAC school, it was taught to insulate the return/low pressure line for two reasons.
1) To reduce/eliminate condensation drips.
2) To help cool the compressor.

Several years ago when the current boat was being surveyed, I just happened to be present when the surveyor was examining the fridge/freezer.

As small talk, I asked why the return line was not insulated.
His answer was a terse..."never done on boats"!!!!

I decided it would be best for me to go grab a bite to eat.