More water heater installation angst

[sparky472]

So, today was the day I was going to install the new water heater. I got a later start then intended, and when I finally got the old pipe installation of the cold water supply and hot water out, I saw that the flex and solder connections were fairly caked up with rust and corrosion, all the way to the drywall (in fact, it looks like the plumber that installed the old heater did some sweat soldering right up against where both hot and cold enter the wall, given all of the scorching and burn marks on the drywall at the opening).

So, I packed it in for today and don't want to give up and call the pros yet. I don't mind cutting out some drywall to get out the old pipes and have some new clean connections. And I don't mind sweat soldering (I practiced a little already). But, if I am cutting the hot and cold copper lines inside the wall, how do I solder new pipe - inside the wall? Or is there another way to connect up new copper pipes inside the wall?

I almost conceded defeat on this, but I really want to do it myself. I was cautiously confident until I saw that I would need to get into the wall to replace some of the lines, but I figure once I know what to do, I can do it. Just don't know what to do... Putting a torch inside the wall to solder a new copper pipe doesn't seem like a good idea...

 

[sparky472]

Are compression fittings reliable enough?

 

[havasu]

I'm having a hard time trying to understand what you are trying to accomplish. Could you post a picture for us retired, slow minded individuals?

 

[sparky472]

I don't have a pic, but I've created a little diagram to help illustrate. I'm replacing a water heater and discovered that all of the pipes - cold water supply and hot water out - are bad, all the way to the wall due to some poor plumbing work when it was installed 17 years ago. So, I need to remove some drywall, cut the pipes and connect tnew copper pipes that will run to the WH. The diagram shows the cold water supply (blue) running up inside the wall and out to the WH. Hot water out (red line) out from water heater back into wall. The sections of both pipes between the wall and the WH need to be replaced. The purple lines represent two potential places to cut the pipe and connect new ones - just depends on the condition of the pipes inside the wall, which I haven't determined yet.

My question is how to connect the new pipes inside the drywall - Using a torch to sweat solder in there doesn't seem safe. I'm wondering if there is a way to solder that connection safely or are compression fittings a reliable alternative.

 

[havasu]

Thanks for the drawing as it makes everything easier to understand. Compression fittings would probably work, but I wouldn't trust them and are usually not permitted within a sealed up wall. If you are concerned about starting a fire, then you could always pay a few dollars for a flame blanket and place it behind the pipes when the torch is being used. And as always, keep a spray bottle full of water just in case.

 

[sparky472]

Awesome - that's exactly what I needed to know. Thanks!