Replies

1. 
   danski0224 | Jun 28, 2005 12:48am | #1

   Soft soldered connections are not ideal for a long term, leak free environment.

   It can be done if you are meticulous with the prep work.

   Brazed connections with a nitrogen sweep is the only way to go for strength.

1. 
   McMark | Jun 28, 2005 02:12am | #2

   I have always seen the pipes silver soldered, never brazed.  I will check with my dad, former UA pipfitter instructor.

1. 
   danski0224 | Jun 28, 2005 02:30am | #3

   Brazed with silver bearing alloy. :)

   The more silver, the stronger the joint. Most places I am familiar with use Harris 5%, but the 15% flows nicer. 

    

1. 
   McMark | Jun 29, 2005 02:13am | #4

   You are right, the refer mechanics always say the they are "soldering the pipe"  According the "Soldering and brazing manual" by the National Joint Steamfitter apprentice committee,  5% Ag material is a brazing rod, and melts at greater than 800*F, the artitrary cut off to differentiate soldering from brazing.

2. 
   junkhound | Jun 29, 2005 02:43am | #5

   Scott:  You need to do some more serious reading first before you wreck your Ebay or HD bought AC. Here are some details of why, in addition to it being illegal to open a freon system without an EPA license (you can get a license on the internet for $25 and an hours study and open book test for DIY work, you cannot hire yourself out with that type license).  

   Can the copper lines connecting an A/C compressor and evaporator coil be soldered using standard plumbing type solder? Well, yes, they can, but expect a crack in the solder due to fatigue within 6 months.

   Is brazing necessary? There are some speciaty solders (ie. stabrite is one i recall) that will work for R22 systems but not for R410A - If you don't know the difference, you need to study more. For Cu fitting with tight joints, a 5% silver phosphorous bearing (Silflos, etc.) works best.  For wider gaps or Cu to brass, a 15% Ag content works better.  

   The compressor and Coil are already charged, with sufficient freon to support up to 15 feet of suction line (1/2 inch copper coil).  This is what made me think you are referencing an ebay or HD compressor purchase -  reread the first paragraph.  What you cannot do is  solder in the lines and open the valves and expect anything to work correctly. First off, the air and  left in the lines is non-condensible at 300 psi, so will drop the capabilities of the AC drastically - even worse, any moiature in the air will freeze and clog you orifice and filter.      Second, the flux and oxides from soldering will clog the filter and possibly the orifice.  After the lines are brazed (as others said in a N2 atmosphere to avoid oxide formation) you need to pull a vacuum of less than 0.5 Torr (<500 microns) to get all the moisture to boil out of the system.

   Will the residual flux left from the soldering process cause problems with the refigerant? Yep, it will clog up stuff.

   Here is what you need to do the job properly in addition to the mormal set of mechnaic and electrician's tools.

   1. a good refrigeration book you have read a few times or more till you understand the principles and practice, ($5 or so at a used book store)

   2. Acetylene oxygen torch and tanks (probably about $100 for torch/gauges, $200 for tanks) plus a few sticks of silphos or similar Ag brazing rod.

   3. Set of pressure and vacuum gauges Used you should be able to find for about $40( an electronic vacuum gauge is a desired item, another $50+). .

   4. A good vacuum pump - $50 min used, $4 qt oil.

   5. N2 or CO2 tank and fittings - for one time go at it, $3 worth of dry ice dumped in a jug with a hose from it will also work to purge the Cu lines for brazing.

   6. If you are a total novice, know that the  refrigerant line slopes and direction are critical - read the books.  My first attempt in the 1960s at a homemade AC using old car parts pushed a compressor rod thru the piston due to an oil slug. BTW, that is where I learned that soldered joints crack quickly also.

   If you want some real caustic verbal abuse (to use as flux?), go to HVAC-talk.com and tell them that you are a DIY who bought your unit on ebay or from smarterway and ask about soldering and getting an internet EPA license <G>

1. 
   slfinney | Jun 29, 2005 05:19am | #6

   Excellent feedback - the instructions were pretty specific about the use of Silfos or equivalent and the N2 wash. Clearly outside my own expertise.

   THe slope of the lines is a concern. The existing system was installed in the attic - 60 feet of refrigerant line in the attic, then a 10 foot drop to the condenser. This replacement system is in the basement, and so the lines will end up dropping vertically three or four feet from the level of the condenser, after a horizontal run of about 10 feet.

   Any issues with locating the coil below the condenser, as in  basement?

   Thanks again,  Scott

1. 
   junkhound | Jul 13, 2005 05:05am | #10

   ans. to  --- coil below compressor ----

   Not nearly as big a problem if you have a scroll compressor. Line needs to rise above concensor and then a 1/2" per 10 ft slope toward it, if not a scroll, some p type oil traps needed also, too muchdetail to go into here, get a good book such as the old Trane AC manual from the 70s or look up the info for traps and slopes on the net at trane/carrier, etc sites. There are some pretty exotic double pipe trap configurations to prevent oil slugging that can trash a compressor if not laid out right.

   re: hvac-talk:  I've trashed a couple of post there where hvac tech try to talk about motors and capacitors and have absolutely no idea wht theyare talking about - thik there is some hvac text out there somewhere with a lot of bogus elec. info.

2. 
   TJK1141 | Jul 12, 2005 06:57pm | #7

   Those same holier-than-thou folks at HVAC-Talk also have a "Wall of Shame" section that showcases the hack work being done by many so-called Technicians. Plenty of examples of soft-solder connections and just plain weirdness. There are highly-qualified, competent HVAC guys, but in my experince over the past six years, they only show up to fix the screw-ups done by bubbas ;-)

1. 
   rich1 | Jul 13, 2005 03:01am | #8

   Some of us are not holier than thou!

    

   Some of us are worse.LOL

3. 
   WillieWonka | Jul 13, 2005 06:14am | #11

   I'm interested in studying this subject myself, if only to become more informed on the mechanics and operation as well as the "whys" of how things are done. I do a lot of home improvement stuff, never anything like this, but if that need should ever arise, I'd like to be reasonably educated.

   With that in mind, you reiterated several times to "read the books" and "study." Do you know of any good books by name/title or author that one could search for to purchase, at the novice level? If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME

1. 
   junkhound | Jul 13, 2005 11:45pm | #25

   re:  "read the books"

   Your library should have a copy (or get one inter library loan) of :

   "Refrigeration and air conditioning", by Air cond. and refrigeration institute, Prentice Hall.  Has all the basics, almost no math, negligible engineering or thermodynamic theory, mostly for the begining technician, probably what you are looking for.  My older copy is about 900 pages. About 15 pages on brazing, etc. buried in different sections. Only 4-5 pages on piping slopes and traps, but enough info for residential single set units.

3. 
   djames9 | Jul 13, 2005 03:44am | #9

   Yes, brazing with a silver bearing solder is necessary. Standard plumbing solder is not designed to operate under the high pressures encountered in A/C systems.

4. 
   WillieWonka | Jul 13, 2005 06:16am | #12

   Ive often wondered, what exactly IS brazing vs. soldering? I do plenty of solder connections for plumbing, but I gather from this thread brazing is  much stronger? I have Acetylene as well. So....what is the difference between brazing and soldering and how is brazing done?

   If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time.  -ME
1. 
   Sphere | Jul 13, 2005 03:23pm | #13

   IIRC, Brazing is a brass alloy, best done with a open flame torch and a stick with the appropos flux.

   soldering is a tin/lead combo, that is a loer temp and therefore softer joint..also using a flux.

   Silve solder is higher temp and stonger meld, using a flux and is less prone to corrosion or acetic wear.

   Flux is the key to heat transfer and anti oxidation while the molten bandaid is trying to adhere.

   I am sure I'll be corrected shortly, by an expert.  Spheramid Enterprises Architectural Woodworks

   I've been welding all day, what is YOUR excuse?

1. 
   BillHartmann | Jul 13, 2005 06:17pm | #14

   From my understanding brass does not have anything to do with it.If the base metal melts and joins in the mix then it is welding.If the base metal does not metal and the fill material metals above 840 then it is brazing, below soldering.http://www.tinmantech.com/html/faq__brazing_vs__soldering__te.htmlhttp://www.tinmantech.com/html/faq_brazing_versus_soldering.htmlAlso you need to watch for the difference between silver bearing solder and silver solder.A lot of the leadless solders for water pipe now have silver in them (silver bearing), but not with the amounts and other alloys that make silver solder.

2. 
   DanH | Jul 13, 2005 08:49pm | #15

   Just to add to the confusion, brazing is sometimes referred to as "hard soldering", while regular soldering is "soft soldering".

1. 
   Sphere | Jul 13, 2005 09:01pm | #16

   I can't claim any expertise in that field. I have silver soldered bs blades, 50/50 lead tin for roofs, and a plethora of electronics in guitars circuts..

   I also have  made lead /zinc pipes from scratch..( literally poured the sheet of molt) and mitered them after conicising them..talk about a bitch.

   I recently have had the pleasure of working witha supple yet firm copper, that is so easy to solder with 50/50..I fear I might lose my knack with the challenging alloys.

   Take a look at any pipe organ ( behind the facade) and speculate how it was done..awesome work.

   We put a 64' stop in a 20' church..

   pics to follow. If my scanner dont die.  Spheramid Enterprises Architectural Woodworks

   Make a sweet noise, it might be the last sound you hear

1. 
   Sphere | Jul 13, 2005 09:21pm | #17

   I hope it is you? the TO box only had this?

   here is not a mitered pipe, but a helluva lot of work..  Spheramid Enterprises Architectural Woodworks

   Make a sweet noise, it might be the last sound you hear

2. 
   DanH | Jul 13, 2005 09:35pm | #18

   Was watching a video of the factory in Canada where they're going to build the new organ for our church. In one scene they're actually casting the sheet metal to be used. Two guys drag a sort of trolley along a long narrow table (maybe 2 feet wide and 20 feet long), and molten metal pours out of the bottom of the trolley onto the table as they go. The hardened metal is cleaned, then goes through several rolling steps before it's ready for forming.

3. 
   Sphere | Jul 13, 2005 09:47pm | #19

   We made a table that was 16' long by 36" and a sluice box on the side rails..table was lined with linen and talc.

    

   Molt was poured in the box, a gate was pulled out and a small slit allowed the molt to pool or flow I guess onto the linen..we ran like hell, two guys , one on each side..towards the tables end..

   The end result was a sheet of lead/zinc 36"x 16'..we then rolled iit up as pipe stock.

   Larger pipes got more zinc, cus the lead would collapse by it's own weight, if not PERFECTLY plumb..

   See: lead=plumbum, Lead+plumbum = plumber. I aint kidding.  Spheramid Enterprises Architectural Woodworks

   Make a sweet noise, it might be the last sound you hear

4. 
   Sphere | Jul 13, 2005 10:14pm | #20

   Here is how it works..ya put the left down nd the right foot out and do the hokey pokey till yer testes shout..

   a roller board converts up and down action to side by side, then up an down again, to open the pallet to the pipe..these can be a separate windchest up to a hundred yrd from the situ of the player..all in wooden links..with leather and felt bushings, to keep it quiet.

   This chest was  pedal stop, behind a facade in Philly pa.  Spheramid Enterprises Architectural Woodworks

   Make a sweet noise, it might be the last sound you hear

5. 
   DanH | Jul 13, 2005 10:32pm | #21

   Yep, that sounds about like what I saw in the video.

6. 
   Sphere | Jul 13, 2005 10:39pm | #22

   breathing lead don't afff...aff...affect...us att all.  Spheramid Enterprises Architectural Woodworks

   Make a sweet noise, it might be the last sound you hear

7. 
   DanH | Jul 13, 2005 11:06pm | #23

   That explains a lot of things.

8. 
   Sphere | Jul 13, 2005 11:45pm | #24

   I highly doubt it.  Spheramid Enterprises Architectural Woodworks

   Make a sweet noise, it might be the last sound you hear