Replacing my gas hot water heater.

[Cozzmo]

Hi, I have replaced a heater before about 25 years ago.
This is a much more involved project though, as I am replacing two (25 year old) 50 Gal hot water heaters with a single new 50 Gal unit.

I have quite the list of items to acquire before starting.
I will not be using sharkbite or pex and remain with regular copper. I am somewhat comfortable with copper, see caveat's below...  :-)

So for today's question...
I have in the past been frustrated with solder going all the way into the pipe.  (Using lead free solder, very old paste flux, Map gas)
I like to see a solder around on the outside with no gaps to be sure it won't leak, but, in trying to accomplish this, (especially uphill soldering). I see a bit of a gap, So I try to apply more solder. More than I should need.
Also,
I am wondering if there is more forgiving solder, and/or flux?
Are they all equal?
Tinning flux OR Paste flux. (I have never gotten to work with the tinning flux).

Thanks,
Chris

[Bartlebooth]

Not a soldering expert myself but have done some.  It should just be a matter of following all the best practices.  Clean/brushed pipes and fittings, clean flux, hot enough but not so hot that the flux burns off, etc.  Maybe watch some YouTube videos to refresh on the details.

Think about "this is what the pros do" versus "this is actually necessary and makes sense".  For instance I doubt you need MAP gas.  Isn't it practically impossible to buy actual MAP gas now anyways?

I guess you could even set up a vertical pipe and practice 3 or 4 times with minimal expense.  A few dollars per try.

[lthenderson]

I have all copper pipes and do all my own soldering. I usually never have problems soldering copper pipe to copper fittings. Where I struggle at times it soldering copper pipe to say a manufactured "solder ready" joint like a frost free hose bib.

Some of the things I do is to mock up the copper pipes and fittings, remove as an assembly and then solder them on a bench so I'm not trying to solder uphill anywhere. I try to end up with a downhill solder if I can when the pipe assembly is finally in place, especially if to a "solder ready" fitting. My plumber has told me that the lead free solder made things so much harder on DIY than the older leaded solder.

[sonofsven]

Another tip is to use a small piece of metal that you can bend into shape behind the soldering, both to protect the wood framing but also to concentrate the heat right at the backside of the joint, in tight quarters that are difficult to move the torch around fully. Tack it in place with a partially driven nail if needed.
Always have a pail of water and a rag, and as soon as you are done soldering (and it's still soft) clean the joint quickly with the damp rag, this will give you nice pretty solder lines.

[Just Joe]

Is the pipe getting too hot with the MAP. Switch to propane for lower temps.

Steam in the pipe? Drips for standing water somewhere in the pipes?

Worst case - call a plumber. They still use copper fittings but they use a crimping tool for the fitting vs a torch sometimes.

When I installed our HPWH I did what I could with solder and hired a plumber to crimp a few fittings that I could not confidently solder. 

Edited: for wording...

[Bartlebooth]

Worst case - call a plumber. They still use copper fittings but they use a crimping tool for the fitting vs a torch sometimes.

When I installed our HPWH I did what I could with solder and hired a plumber to crimp a few fittings that I could not easily solder.

I was going to recommend that they use crimp fittings, but I know they have a gasket inside so essentially are similar to Shark-Bite which they said was not under consideration.  BUT, just a couple days ago I saw in a video that someone claimed tests have been done of taking the gasket out before crimping the fitting, and it still ends up watertight.  Pretty crazy if true and should move them more into consideration.  (TBH they should have been fair game anyways...)

Oh and you can get a hydraulic press/crimp tool for ~$130 online.  Manual of course--brand name electric ones are still $3,000.

[Just Joe]

I have some reservations about the crimp fittings so I only used them where I can view and access them. Its my own experiment to see what their durability is like. Can't imagine putting them inside a closed wall - yet.

Edited: typo

[Mgmny]

I have quite the list of items to acquire before starting.
I will not be using sharkbite or pex and remain with regular copper. I am somewhat comfortable with copper, see caveat's below...  :-)

I have in the past been frustrated with solder going all the way into the pipe.  (Using lead free solder, very old paste flux, Map gas)
I like to see a solder around on the outside with no gaps to be sure it won't leak, but, in trying to accomplish this, (especially uphill soldering). I see a bit of a gap, So I try to apply more solder. More than I should need.

Seems to me that the solution to your soldering problem would be using a sharkbite / pex fitting. :)