Joining copper pipe to aluminium pipe

[Troll Hunter]

As in the title.  I need to join these two dissimilar metals for a mod on my CSW cabin heater.  It appears that Uniweld 4300 (P4KD9) is the recommended method, but is there a cheaper method/process/material that anyone can recommend, please?  I'll have to sell a kidney to buy that Uniweld product🥺.  Muggyweld Super Alloy 1 is even more expensive.  I'd have to sell both kidneys, plus a few other parts!

Is it possible to use something like JB Weld, a 2-pack "epoxy metal" that sets hard and seems to adhere to almost anything?

All recommendations will be very gratefully received.

Mike

[Cynic-al]

Can you not thread or put union nuts on the pipes and join mechanically? It have a bit of rubber hose between them? 

[Eightpot]

Rubber hose and hose clips?

[Bowie69]

What size pipe?

[smallfry]

What is the size difference, if any ? would one slide inside the other  ?

[Stellaghost]

I've used universal solder to join aluminium to copper you tin both with the solder and then push together and solder the joint regards Stephen

[Stellaghost]

Just to add there is a company in America called Lucas Milhaupt that sells flux cored brazing rods to join aluminium to copper 4 rods for $25 they also demonstrate how to use said rods on their website hope this helps regards Stephen 

[cackshifter]

Or maybe a compression fitting?

[Gazzar]

Flare the end and then use suitable hose and clips.

Should also assist with vibration.

[Troll Hunter]

Thank you, all, for your replies and suggestions, some of which may be applicable.  I should have included photos in my OP, so here they are.

My vehicle originally had A/C, but when I replaced the V8 with a 300Tdi I did not have an A/C compressor.  I now have 4-60 air conditioning - four open windows and 60kph.  In Canadian summers that is OK.  It's the winter period that I'm trying to cater for. 

What I am now trying to do is add another heater core to the original heater box, having removed the A/C evaporator core.  The photos show the reconfigured pipework and the two copper elbows I want to attach.  All the piping is nominal 1/2", as in traditional domestic plumbing.  As you can see, space is limited.  I can still remove the new heater core to work on the two pipes, but the final solution has to fit into the box.  I am already planning to use 1/2" bore rubber heater hoses to connect to the flared ends of the aluminium pipes.

Compression fittings may be suitable, since I can cut back on the aluminium pipe which has a 90 deg. elbow, to give a bit bore room.  I don't think that threading of the pipes is an option since the wall thickness is only 1.11 mm, and thread depth is virtually that.  If I find that compression fittings don't do the job I'll reluctantly fork out for one of the soldering options.

So, thank you, everybody, for your input, and I'll update with the final solution.  Meantime, keep healthy.

Mike

[Eightpot]

If you're going to attach 1/2" rubber hose to the aluminium pipes, why are you adding copper sections in at all?  Use heater hoses from a V8 or Defender which have the correct I.D and tight bends to clear the box - join them directly to the matrix.   I wouldn't trust any kind of soldered connection between copper and aluminium.

[ballcock]

If they are 15mm od I would use a compression fitting or a speedfit push fit elbow both are easily demountable if necessary. I solder a compression olive to 15mm pipe to create the lip for the hose to go over. You can solder copper to ali there are also some metal adhesives used in the plumbing trade to join copper pipes that might work.

[FridgeFreezer]

Gawd looking at the plumbing I'd cut the ali pipes a bit closer (so it's a fairly straight end), bead or flare the ends and just put cheap eBay silicone elbows on.

[missingsid]

Here's the real problem!!

"I replaced the V8 with a 300Tdi"

 

 

[FridgeFreezer]

2 hours ago, missingsid said:

"I replaced the V8 with a 300Tdi"

This displeases the gods and leads to bad Juju

[ballcock]

1 hour ago, FridgeFreezer said:

This displeases the gods and leads to bad Juju

I have to agree, if I could find a cheap suitable gearbox I would be fitting my 3.9 in place of my 200 Tdi.

[Troll Hunter]

8 hours ago, Eightpot said:

If you're going to attach 1/2" rubber hose to the aluminium pipes, why are you adding copper sections in at all?  Use heater hoses from a V8 or Defender which have the correct I.D and tight bends to clear the box - join them directly to the matrix.  

A good point.  Thank you for prompting me to look in the parts manual at V8 hoses since I had only been looking at 300Tdi ones.  Something about not seeing the wood .......

I'll get a couple on order and see if I can totally avoid using copper elbows.  I'll update, but it'll be a couple of weeks, at least, before I receive them.

Mike

[Tanuki]

Be aware that copper and aluminium are rather far-apart in the 'electrochemical potential' scales, meaning that when connected together in the presence of an electrolyte such as water they'll do their thing and turn into what amounts to a short-circuited battery - so one of the pair will be rapidly eroded.

To stop this, you really need to use a serious non-ionic coolant/antifreeze/corrosion-inhibitor, in serious concentration!

[Troll Hunter]

Good point, Tanuki.  I was aware of the galvanic cell problem, but hadn't decided how to tackle it.  If I can use rubber hoses and no copper elbows I should be able to avoid major problems.  On further examination of the original V8 heater core, which I am still using, it appears to have brass connection pipes, or at least some yellow metal, as does the 300Tdi radiator.  After some 20+ years of use there doesn't appear to be any significant corrosion.  There is some internal corrosion in the steel pipe that runs along the top of the rocker cover to the cabin heater.so this might require replacement.  Land Rover obviously got the yellow metal alloys close enough in galvanic potential to minimise corrosion.

Mike