"Phil Scott" wrote in message
...

"RicodJour" wrote in message
oups.com...
I'm closing in a room that has a chase located next to the
chimney. I
want to run lines for a future central air system while the
wall is
open. There's a crawl space below, marginal access on the
second floor
and good access in the attic where the air handler will be
located.


If its not a stand up attic with stair step access (not a
ladder) your repair guy will hate your guts... not to worry
about him though, he will just all the grief to your
bill...with a smile.





I
picked up a 50' 3/4" & 3/8" line set which will work with
the
anticipated 2 or 2.5 ton 2nd floor load.

yes that works

PS... one caveat.. best is to avoid soldering. the 2
ton unit will have a 5/8" suction line probably and a 1/4"
liquid line. so if there is a miss match you will have to
solder.

also if the evaporator coil is above the condensing unit the
fat suction line you are showing will work just fine, and
advantage actually... if the air handler / coil is below the
condensing unit, the fat suction line can pose 'oil return'
problems if its much of a rise... if thats the case bend a
slight trap into the bottom of the riser on the larger line.
a riser over 10' should be avoided.. especially if you end up
with an oversize suction line as you are showing in the event
of the 2 ton unit (size also dependent on the efficiency of
the unit, check all that out...with the smaller unit, which
should be fine the 5/8" suction line is a lot easier to bend,.
you can avoid all the soldering.

bending trick,, try to arrange bends to match the way the tube
is already coiled...bending it sideways or backwards is more
difficult.. you can rent a lever arm tube bender for that
though.

Phil Scott






My questions:
- I don't see how I'll be able to run the line without
having at least
one or two cuts/couplings. I've read silver brazing is
better than
sweating the joints. How critical is the difference?

Best by a massive margin is run it without any cuts
solders or brazing..those cause oxide inside the tube and
that oxide seeds nasty chemistry into your system and
shortens its life significantly..if you do braze run a dry
nitrogen purge through the line when you do it.... 15%
silver brazing rod is best, called silflos in most stores is
best, you need an oxy actytlene torch for that.. over 1500
degrees to work well.

dont flux the joint, the acid gets into the tube that way
and seeds bad chemistry in the operating system.


- Is flux a problem with making connections in a
refrigerant line?
Alternatives?

Use an oxy/ actylene flame, get it neutral, then open the
oxygen valve slightly to get a faint 'feather' on the
flame..test it on a tarnished penny... when its right the
penny will turn bright copper under the flame..if its wrong
it will darken or soot will show up...


- I'll be pulling a 12/3 line for the unit and to provide
an additional
circuit in the attic. What wire should I pull for the AC
controls?

Run 10-2 with a ground... you dont need 3 conductors for a
single phase system...you will get about 2% less voltage
drop on a hot day when the voltage is low anyway... 12/2
would work though for 2.5 tons but its skimping. (the charts
are irrelevant to whats best for your system, the charts are
for fire safely purposes, the NEC is part of the national
fire code)




- I've never pulled such a large line. With electrical I
use a fish
tape. Can I use that to help pull the insulated copper?
Any tricks to
keep the insulation from hanging up and getting ripped?


In buildings less than 3 stories you dont need conduit
inside the walls... for ac in those cases run romex. where
it goes outside run the romex into a box..then run rain
tight conduit outside to the condensing unit etc.

Phil Scott
Mech/ Electrical contractor since 1210...



Thanks.

R