Sweating copper is a pain in the neck for most
home owners. But its worth it! You can do things with copper impossible
by any other means. In old office buildings I've taken 1 1/2 in.
malleable copper tubing, run fifty foot coils through a rolling mill so
it's less than the thickness of the 3/8 to 7/16 floor lathing. I've run
it under hand inlayed floors fit for a palace, insulated it with "Sockz
cloth" at a dollar an inch, so heat wouldn't crack or separate the
inlays, reformed sized and broached the ends to fit standard 3/4 in
copper fittings and used a reducing fitting to 1/2 so someone in a
wheelchair could have a toilet where he wanted it. A drain was handy
but no water.
Keep all your repair copper and bronze fittings in
a Tupper type plastic box with some old chopped up newspaper. If your
stuff is dirty and corroded, in half a gallon of boiling hot water put
one quart of white distilled vinegar, throw about a pound of your
fittings and return to a boil, then simultaneously add 1/4 cup of Arm
& Hammer Sodium Bicarbonate and 1/4 cup of Salt. This is going
to boil like crazy so best to do it in a large bucket. Using a paint
stick stir like mad! add more Sodium Bicarbonate and salt checking the
color of your fittings. Once they are clean rinse with clean water dry
in shop towels and lay out to sun dry. Whatever you do, if you have
cleaned any threaded copper fittings rub the threads (screw in - screw
out) with some steel wool "0" is a good choice.
When you begin your project, draw it out exactly,
make sure you have more "L", "T", hoppers and "45° L" and
"geegaw" fittings than required. Precut as much of the rigid tubing as
you can and assemble those parts of it first. I assure you it is much
more pleasant to sit at a picnic table drinking an icy cold Budweiser
sweating copper like a jeweller making a ring.
"...and yes Ma'm... I would like another
Budweiser, thank you! and thanks, your brownies are fantastic! Hummmm
better to labor so than it is to labor long unseen, misunderstood and
not appreciated under the stinking cold wet foundation of someone's
house... where only God knows what has leaked out.
So, you already know the first rule of sweating
when you can.
Now what does it mean to pre-sweat. It means
immediately after you've cleaned your fittings either old or new, you
drop them, except for all the threaded ones of course, into a ripe
solder pot . To know
when to drop, you rake the top of the solder pot, there should be a
film of rosin on top. Gaze at the mirror for a few seconds, if it is
wet with rosin and does not discolor in 5 seconds but discolors within
20 seconds you're ready. Drop in your parts, stir with due diligence
and kick on the afterburner for more heat. Keep adding resin as the
mirror clouds. Dig down into the lead and stir the parts bring them to
the surface to meet the resin, observe the mirror every 15 seconds. You
want to go against the grain here by using Rosin ( or Resin) instead of
acid flux. Don't forget to stir. In a pinch you can get Rosin at the
pharmacy. Next thing after about five minutes of increased very high
heat you want to pull all these puppies out of this very hot pot and
with considerable care violently shake off all the excess solder. This
is best done in a wire mesh stainless steel basket. It is very
important that the fittings are covered with a thin layer of solder. If
they have globs and stick together, you need to turn up the heat and do
it again. Please be careful around a pot of hot metals. Please shake
hot solder neither upon your person or your clothing. You have been
In the design of a copper water system you should
make a low point (drain) where the water goes into the heater that's
the key. Somewhere close by there should be H & C Drains which
are physically the absolute lowest points in your entire copper
plumbing system. You should create vents at the highest points in your
system, you may create additional vents in long runs which might not
drain well without air. In my Library behind " The Letters of Horace
Walpole" there are two little 1/2 in. gate valves that vent both H
& C to the air, facilitating the draining process. Their risers
go to the roof so accidental actions do not result in water in the
house. Drains and vents help you greatly when you have to repair or
modify a copper installation. Do consider too, making close union
fittings on valves. Always use gate valves which aren't likely to wear
out. Gate valves should be either open or closed and nothing
in-between. Do not use a Gate valve to control the flow of water. If
you keep a spare unit, when a Gate valve begins to leak you can unscrew
the union fittings and replace that puppy in five minutes. No solder no
sweat! All I've got to say about washer valves is that I don't like
them. In my opinion valves should not be used to moderate the flow of
water, that's what faucets are for.
How to Sweat copper. Clean the ends of rigid
copper with a stainless steel wool rubdown. Either paint or dip the
surface in a pudding or liquid resin flux put a cold torch (propane) to
the largest piece close to but not on top of the place you want to join
do not heat a previously joined fitting. When hot wet it with lead.
wasting no time clean it with steel wool "#0" is good for this.
Take a pre-tinned part in a pair of slip-joints,
align them as close as you can. Heat both pieces by switching quickly
one to the other. When you see all the lead melted continue to heat for
15 seconds, then gently join the pieces. They should go together like
Romeo and Juliet! Once joined, continue to heat for 15 seconds. Now
take a piece of bar solder and continuing the heat rub this against the
joint. When the joint will not accept solder you're done. Never under
any circumstances cool a sweat copper joint with a wet rag or with
water. Don't move anything until the solder has set otherwise you'll
likely have a leak.
In less than ideal circumstances when you can not
control the flow of leaking water you'll not sweat a darn thing. I've
used the skin off KFC original recipe, KFC biscuits, white bread, or
toilet tissue to plug a pipe so I could sweat the job. Bread is the
best as it readily breaks down when water pressure is applied. Before
you apply pressure be sure you remove or bypass all water filters
including faucet strainers. Once the water has run sufficiently to
clear out anything that might be in the pipes, return your filters to
normal and put the strainers back in.
Support fittings are available which will rigidly
suspend copper plumbing 4 inches from the wall when copper is exposed
as with heating and radiators or in institutional plumbing where there
are service corridors and inspection ways. These fittings facilitate
the modification or repair of copper lines since they greatly reduce
the incidence of damage to paint, woodwork or wallboards due to
Whether you're building a new home, renovating or
just fixin' up, you should seriously consider copper. Copper will
supply clean water, it won't corrode or rot, is easy to repair if
installed properly and is more resistant to freezing than PVC. Copper
is malleable and can be formed into complicated shapes when the job
requires. Copper will do things impossible with PVC or Iron.
Advice for Mr. Fix-It. if you're 30 and building
your home with Iron pipe, just remember in most parts of the States, in
about 35 years you'll probably have to re-tube the house. That means
when you're 65, do you really want to take on that job and if not, do
you want to pay for it? With copper you'll never have to re-tube.
There has been a lot of exposure about lead in
drinking water plumbing. Proper application of solder to copper does
not result in a lead problem. The key is this, wet the joint but don't
make it drip. Be easy with your hand. -
Nice site! Hi
Good site, but I disagree with one of your statements: "With copper
you'll never have to re-tube. "
This just isn't true. In my experience (as a plumber in the UK),
untouched copper pipework will generally leak within 15 years of
installation. This is most often caused by flux residues on or near
soldered joints, but in all pipework the copper gradually wears away
and a leak can occur anywhere.
The degree and type wear differs, of course, between cold supplies and,
for example, wet central heating pipes. In the former the minerals
passing through the pipe acts abrasively, and in the latter the
repeated expansion and contraction causes work hardening of the copper
and also stresses the joints.
Another factor is that few installations not lie untouched for 15 years
- additional runs and styling changes in basins and such like will
require joints between new and old pipework. If the old pipe is very
old then it is invariably very thin, and when nearing its retirement it
doesn't always withstand the forces involved in making a joint.
Just thought you'd like to know :)
Tim 29 Mar 2005
More from Bill on Sweating Copper
I know where you are coming from. Most copper plumbing is sweated with acid
flux which leaves a corrosive residue both in the solder and on the surface.
Even if you clean the joints with bicarbonate of soda, you still do not get
all of the acid and, yes those joints will fail. That is why I recommend the
use of Rosin or Resin flux.
On the other matter of the erosion of pipes internally, this is generally
not a problem Stateside as we have very high standards regarding the
contents of the Municipal water sources. But, in rural or unincorporated
areas which do not maintain a competent Water Control Board, when the water
source is not managed by a public utility or is a private well, and you have
no way to control the mineral content or the PH, (relative acidity) then the
problems you describe are exactly precise regardless of the flux used. -- "Bill McCaslin"
Pre-Sweating you are recommending 80/20 lead solder that is illegal in most states except the places where there so stupid from lead brain damage. dude!!! -- mark
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Mending fences is often more productive than building walls - Axel Klystrom