Newbie Question on copper tubing

theoldwizard1 · 11-01-14, 09:34 AM

Looking at a modern mini-split heat pump, it is obvious that different type of copper tubing is used. Soft (bendable) tubing for the line set and hard tubing (pipe) for various "plumbing" inside the interior and exterior units.

Are the hard copper pipes Type M, L or K or something else ?
Can you use "common" sweat fittings, even though they are brazed, when plumbing a DIY heat pump systems or are special refrigerant fittings required ?
Are the soft (bendable) lines the same as what is used for water or are they special ?

NiHaoMike · 11-01-14, 10:32 AM

It's all about the pressure ratings of the pipe, the requirements of which are application specific. Also, you might have to clean "regular" pipe before using it, while ACR pipe comes precleaned.

theoldwizard1 · 11-01-14, 11:26 AM

Quote:

Originally Posted by NiHaoMike

It's all about the pressure ratings of the pipe, the requirements of which are application specific. Also, you might have to clean "regular" pipe before using it, while ACR pipe comes precleaned.

Ah Ha ! You just gave ne the lead I needed !

The "Copper Tube Handbook" says

Air-Conditioning and Refrigeration Systems — Copper is the preferred material for use with most refrigerants. Use Types L, ACR or as specified.

Types K, L, and M, are designated by ASTM standard sizes, with the actual outside diameter always 1/8-inch larger than the standard size designation. Each type represents a series of sizes with different wall thicknesses. Type K tube has thicker walls than Type L tube, and Type L walls are thicker than Type M, for any given diameter.

Copper tube for air-conditioning and refrigeration field service (ACR) is designated by actual outside diameter.

ACR is available on both annealed (soft) and drawn (hard) tempers. Annealed is available in coils or straight length s. Drawn is only available in straight lengths. Drawn has a much higher working pressure than annealed.

The short answer is, use ACR, annealed or drawn as the application requires. The bummer for DIYers, is that this is probably not available at your favorite home center.

NiHaoMike · 11-01-14, 12:16 PM

You can get by with Type L or flexible copper (given enough pressure rating) for most applications. Just use an air duster to remove any dust inside.

11-01-14, 09:34 AM	#1
theoldwizard1 Apprentice EcoRenovator Join Date: Oct 2014 Location: SE MI Posts: 105 Thanks: 3 Thanked 12 Times in 9 Posts	Newbie Question on copper tubing Looking at a modern mini-split heat pump, it is obvious that different type of copper tubing is used. Soft (bendable) tubing for the line set and hard tubing (pipe) for various "plumbing" inside the interior and exterior units. Are the hard copper pipes Type M, L or K or something else ? Can you use "common" sweat fittings, even though they are brazed, when plumbing a DIY heat pump systems or are special refrigerant fittings required ? Are the soft (bendable) lines the same as what is used for water or are they special ?

11-01-14, 10:32 AM	#2
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	It's all about the pressure ratings of the pipe, the requirements of which are application specific. Also, you might have to clean "regular" pipe before using it, while ACR pipe comes precleaned. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

11-01-14, 12:16 PM	#4
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	You can get by with Type L or flexible copper (given enough pressure rating) for most applications. Just use an air duster to remove any dust inside. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...