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Heavy section pipes, forged elbows, left-hand threads: steel heating systems are not suitable for altering the interior space of old homes. To move a radiator in the living room, or add the comfort of a towel warmer in the bathroom, you have to marry steel and copper. Manual.

connection of steel and copper pipes

Practical advice

Do not use fiber seals (red) for brass fittings in a central heating system. Prefer blues, designed for water, gas and high temperatures.
Before embarking for the first time in the braze-solder, take the time to test and always heat the largest metal mass, namely the steel pipe.

Need faucets

All the central heating installations were working, not so long ago in thermosiphon, without water circulator. The system is simple: the boiler, installed in the basement, produces hot water (heat transfer fluid) that rises through the supply network to the radiators, while the colder, heavier water goes down into the ground. the return circuit to the boiler.
● In order to limit the pressure losses caused by pipe lengths and travel accidents (elbows, pipe connections of different sections, etc.), this system requires large section pipes or the presence of valves.

Precautions

For this type of installation, copper pipes are required. They are manageable, easy to cut and easier to implement than steel. But you have to take some precautions to use them.
● Never use a copper junction to connect two steel pipes. An electrolytic phenomenon would lead to corrosion of the less noble metal, steel, and thus to its slow deterioration.
● For the same reason, never do any branching (secondary branch bypass connection on a main line) copper / steel on a buried pipe.

Brazing

Two methods are available to the do-it-yourselfer to make adaptations on his steel heating circuit.
● The first is the quilting of a copper pipe by braze welding. This technique is almost mandatory on large section steel tubes. It calls for a high temperature to heat the mass of metal that is obtained with an oxyacetylene torch. Small oxypropane materials are not suitable for this purpose at all, nor are ordinary cartridge-type soldering lamps.
● After emptying the pipe (to be done in the summer), the pipe is drilled in the place intended for the stitching. The drilling is done to the exact diameter of the reported tube, if it is nested; or by reducing the diameter by two millimeters for a surface contact of the pipe to be soldered. In this case, the end of the copper tube may be slightly flared to provide a wider bearing surface.

Threading

The other method - more accessible - is to use brass fittings, screwed onto steel fittings with a sealing paste and tow.
● This technique offers two advantages: it does not require welding equipment and requires less precautions for complete emptying of the installation than soldering. Simply remove the screwed connections or elbows and replace them with brass fittings where the new copper pipes will start.
● Depending on the case, the right-right or left-right connection sleeves will remain in place or need to be replaced. Note that the "left" pitch for brass fittings does not exist.

Brass Fittings, Filler and Sealant are available at hardware and plumbing ranges of DIY superstores.

Drill and enlarge

Drill and enlarge

Drill a small diameter pilot hole (Ø 3 mm) into the pipe on which the copper pipe will be grafted. Then increase the diameter of the hole to facilitate the passage of water and prevent the flow is slowed down.

Perform a blank edit

Perform a blank edit

Make a blank mounting of the pipe on the steel pipe. It keeps in place, and in the desired position, the element to be soldered first, in this case, here, an elbow.

Picket

Picket

Avoid tapping too close to a threaded connection. This could burn the tow and compromise the seal. If you can not do otherwise, wrap a damp cloth over the hose before operating.

weld

weld

Use alloy rods coated with paint stripper. Focus the blowtorch dart on the steel before applying the wand. The molten metal will spread by capillary action on the copper.

Fittings with opposite steps

Fittings with opposite steps

The two discontinuous lines (1) and the line with an arrow (2) each indicate a connection with opposite right-left steps. The right-to-right connections can be identified by a solid line.

Strip the nets

Strip the nets

Brass fittings are not intended for use with tow. A very effective method is to scratch the nets with a hacksaw blade before wrapping the plant fibers.

Wrap the tow

Wrap the tow

Fill the threads with sealing compound and wrap the towing strand flat, turning clockwise. It is better here not to use Teflon tape.

Joint fitting or union-union

Joint fitting or union-union

The male-male nipples screwed onto the steel receive fittings to extend the copper installation. Mixed screw fittings with soldered flange, or unions, seamless.


Video Instruction: How to Connect Copper to Galvanized Plumbing: Plumbing Repair