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gsracer
31-12-2015, 11:32 PM
I need some advice please

this is not my usual work but I have leak on a domestic fridge on the silver solder joint between the copper and aluminium, I've never tried silver soldering aluminium to copper before any advice appreciated

Thanks Kevin

chemi-cool
01-01-2016, 06:10 AM
Its not silver as silver melts above aluminium melting point.

To solder it you can use aluminium rods and a lot of flux and it will stick to the copper.

nike123
01-01-2016, 09:58 AM
Very hard to do it without lot of practice! Melting of aluminium pipe caused by excess heat is very likely. Your better option is to do it with these sticks:

http://www.laco.com/repair-sealants/heat-seal-stik/

Glenn Moore
01-01-2016, 12:37 PM
Hi Kevin
Soldering Ali to copper is a fine art which needs a lot of practise as I used to demonstrate this at various AC&R shows some years back . You can get a weld kit called Aluma Weld which comes with a sintered flux and a reel of Ali weld rod. It does an excellent joint ,providing you don't melt the aluminium completely as Nike and chemi mentioned. I would not recommend doing it inside a fridge as its a delicate thing to do. So as Nike said get a Laco stick from Dean & Wood or one of the other wholesalers. You simply clean the leak area with emery cloth or wire wool then heat the area with a lamp carefully and wiping the Laco stick over the leak . As the stick melts like a glue you push it into the leak to seal it. After you have sealed the leak it is important to paint over the whole joint area to prevent further leaks by electrolytic action as the Ali / copper junction is a battery and in air will rapidly corrode, so borrow your Mums or girlfriends nail varnish and paint over the whole joint to seal it from the atmosphere then you should have no further problems

Grizzly
01-01-2016, 01:08 PM
Sound advise guys!
Thanks.
Grizzly

monkey spanners
01-01-2016, 01:23 PM
I got given some special self fluxing rods after a visit to the RAC show, they are for the Lawton Dual pipe which is an ali covered copper pipe, so when you swage to join you are joining copper to ali.

I have yet to try a copper to ali joint but have brazed up a cars aluminium power steering radiator where it go rubbed by the fan (van was in for a service and i can't keep my nose out of other peoples business...) was really easy to do but you don't need much heat and needs to be very clean, i used propane on a mapp torch.

Lawtons demo vid,

https://www.youtube.com/watch?v=8GbHR3gJEr4

The joint needs covering with heatshrink once cooled etc to prevent corrosion.

Quality
01-01-2016, 02:27 PM
I got given some special self fluxing rods after a visit to the RAC show, they are for the Lawton Dual pipe which is an ali covered copper pipe, so when you swage to join you are joining copper to ali.

I have yet to try a copper to ali joint but have brazed up a cars aluminium power steering radiator where it go rubbed by the fan (van was in for a service and i can't keep my nose out of other peoples business...) was really easy to do but you don't need much heat and needs to be very clean, i used propane on a mapp torch.

Lawtons demo vid,

https://www.youtube.com/watch?v=8GbHR3gJEr4

The joint needs covering with heatshrink once cooled etc to prevent corrosion.

Ive repaired a few vehicle ac pipes using the same method. As you said it doesn't need much heat

Tayters
01-01-2016, 03:57 PM
If you want a laugh I tried to get the local kebab man out of trouble when his domestic fridge he kept for drinks developed a leak. Copper pipe came out of compressor, into a lokring then aluminium. Cut out leaky lokring, swaged and attempted braze with silver solder. Yep, in the space of a heatbeat I'd fashioned a perfect hole.

Hmm, get out of that one. Well I did.

Ended up brazing 1/4" access port into compressor then flaring aluminium pipe.

Compressor gave up a few weeks later...

monkey spanners
01-01-2016, 04:42 PM
If you want a laugh I tried to get the local kebab man out of trouble when his domestic fridge he kept for drinks developed a leak. Copper pipe came out of compressor, into a lokring then aluminium. Cut out leaky lokring, swaged and attempted braze with silver solder. Yep, in the space of a heatbeat I'd fashioned a perfect hole.

Hmm, get out of that one. Well I did.

Ended up brazing 1/4" access port into compressor then flaring aluminium pipe.

Compressor gave up a few weeks later...


Its always when you are helping out it all goes south.

gsracer
01-01-2016, 06:02 PM
Thanks for all the advice men I think I'll try the Laco stick and yes it's always the free jobs that cause problems it's my brothers fridge !

Thanks Kevin

charlie patt
01-01-2016, 11:51 PM
You can buy a proper alloy to cooper Vulcan locking that will do it if u ain't used to the solider bit it is very easy to blow a hole in it u should use a proper pair of pliers to crimp um in but there are other home made versions that would do it the joiners ain't dear