What's the difference between copper fittings rated for ACR (like
Mueller or Nibco 96XX) vs. standard copper fittings sold at H/W
Is there any issue in using the generic wrot copper fittings for HVAC
Have you ever used a standard fitting in a pinch?
Is sizing the only difference?? Would a 7/8" ACR coupling be
identical to a 3/4" water coupling? (ie nothing different about the
metalurgical properties of the copper that make it better for HVAC)
On Sun, 28 Jan 2007 17:45:57 -0500, "Stormin Mormon"
I regularily use standard copper fittings on refrigeration lines. But
there are enginering considerations
There are three grades of copper piping. These are labeled K, L, M
L is also called ' blue" M is also called " red "
Refrigeration is always L or K as M is not acceptable. Soft copper
or rolled copper is usually a L grade.
Secondly any copper used must be exceptionally clean. Refrigeration
copper has a 'dry' gas inside to keep out the moisture. Moisture will
destroy a compressor motor. And be expensive. Technicians know how
to remove the moisture.
Fitttings. Couplings and Tees are almost the same. Elbows are
not. Most water elbows are short radius and creates back pressure
friction greater than is acceptable in refrigeration. You will
need to go to a plumbing wholesaler to get long radius elbows that can
be used with refrigeration. An alternate is to only use 45 degree
elbows as they do not restrict as much.
Solder -- Soft solder can be used in some reffrigeration but probable
not what you are doing and not with the off the shelf flux. So you
will need to get a high temperature solder with a high temperature
One correction if I may.
Most think the nitrogen is to keep moisture out because it will hurt the
compressor. Well, if that's so, I want to see who is fast enough to pull the
end cap off and soldier it in place before moisture and air get into the
The nitrogen is in the tubing to prevent it from oxidizing over time before
the tubing is used. Its the installer who needs to purge the tubing before
soldiering and evacuation.
If one installs a system and comes back months later without first
evacuating and then pressurizing with nitrogen the tubing will oxidize and
cause possible problems with valves and the compressor, how much depends.
I know this is an old post but here is the dif:
The Hardware store (Plumbing) copper fittings and pipe are only rated up
to 200 PSI pressure. ACR or HVAC/R fittings and pipe are rated to min 600
psi. NEVER use Plumbing fittings or pipe on AC units. They can crack and
even burst in the higher pressures. Not worth the risk of injury and the
cost of repairs.
Be sure to use silver or silver alloy solder/brazing rod.
Also - make sure to use an acid free flux and don't over flux - the excess
will get into the refrigerant/compressor oil.
Simple tips but they will save you hundreds in repair costs later on.
Reason for this is to reducer possibility of fracturing under vibration.
I recommend that you seek experienced help for this kind of work. A
licensed bonded and reliable HVAC contractor/Master Tech will save you a
lot od grief and will also warrant the work against failure.
Pressures you indicated below are Working Pressures
Bursting pressure are some what much more higher
I don't know off hand for plumbing but refrigeration
Standard is 900 PSI some Mfg. could be little different
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