I've posted before about my exploits in fixing leaking copper pipes. I've amended my previous post as I've since found out, through experience, that using consumer grade epoxy is not a viable option, for two reasons. First, because it is only graded to withstand temperatures of up to 120 degrees Fahrenheit, and if you are using it on a baseboard heating system, it is likely that your pipes will reach upwards of 140 degrees. And second, because there may be some issues with using epoxy on potable water (the pipes I was using the epoxy on were non-potable, so it wasn't an issue, but it still means this was not a general solution).
The right way to fix a leaky pipe is to replace it! This may sound difficult, but it is actually pretty straightforward, and anyone with a small amount of do-it-yourself home improvement experience should be able to handle it. I had help from a friend who had done it before, but after just one time, I feel confident that I could do it by myself.
Here's what you will need to get started:
We begin with my favorite part of the project, the demolition. Make sure you drain the line first (shut off the water supply from the furnace, find a drainage spigot and attach a hose...). You can either cut out the bad section of pipe with a hacksaw or remove a section at the nearest joints using the torch. If you use the hacksaw, clean up the ends of the cut pipe with the pipe cutter tool so that they are nice and smooth. If you are using the torch, just heat up the joint where you want to remove, make sure the pipe isn't hot, and pull it out with either gloves or pliers of some kind (and be careful, the pipe ends are HOT! Dip the removed pipe in water as soon as you can to cool it off, then discard it).
Now you're ready to put in your new pipe. The best thing to do is measure exactly how much pipe you are going to need, cut the pieces first, and fit them in place before you begin to solder. When you cut a piece of pipe, make sure to clean the smooth out the edges of the cuts with the pipe cutting tool, removing any burrs that may prevent the solder from sealing the opening. Make sure everything fits perfectly before you do anything else. Then, disassemble your pieces and prepare them for soldering. First, take some sandpaper and score about 1 inch on each end of the pipes and the insides of all joints. Then, coat the outside of pipes and inside of joints with flux. Now, reassemble the pipes in place and again make sure they fit perfectly.
Now you are ready to solder. Start at your first joint, and position the flame retardant cloth so that when you are heating the joint, you don't burn your house down. Hold the solder in one hand, the torch in the other (or get a friend to help). Turn on the torch and heat the side of the joint in which you want the solder to flow (so, if I'm joining a piece of pipe on the right side of the join, I want to heat the join on the right side, not the left side of the pipe). With the yellow Bernzomatic torch, it should only take a few seconds for the pipe to reach the right temperature. Spool out a long piece of solder and gently touch it to the pipe along the joint. If it melts, the pipe is hot enough. Touch the solder to the pipe in a few places, the flux should carry it around the entire circumference of the pipe. Shut off the torch, and examine your handiwork, and move on to the next join (but be careful, the pipe is still HOT!). When you are finished with all your joins, turn on the water and check for leaks. If you're lucky there won't be any, but if there are, you'll have to remove that section and try again.
One more thing. At Home Depot, they now sell pre-soldered joints. These joints have solder already inside the joint, so all you have to do is sand them a little, apply flux, attach and heat. They work really well and make the soldering part of the job much easier. The good thing is that they are really inexpensive, so I think it's worth the few extra cents for the convenience.
And that's about it! You should never have to call a plumber again (unless the pipe you are fixing is in a really hard-to-reach spot). There's many books and tutorials you can read that explain it, but take it from me, this is really not that hard to do, it just takes patience and precision. Good luck!
[Update: Since publishing this, I've found that this solution is less than perfect. The epoxy I used tends to melt if used on hot water pipes. I am looking to see if I can find an epoxy that can withstand high heat. In the mean time, this may not be the best solution.]
We've recently had some problems with our baseboard heating system; the pipes that carry the water throughout the house are made of an old material called bundyweld, which is no longer used, as it tends to rust and leak. Our is almost 60 years old, and has started leaking periodically. We've gotten some of the pipe replaced, but not all, and in the mean time, I've developed a pretty good system for plugging these leaks until we can pony up the dough for the big project of replacing the entire system with copper pipe.
First thing is: locate the leak. A pinhole leak usually shoots water in a stream, so look around the pipe for a stream of water, but be careful, as the water will likely be very hot.
Once you've found the leak, shut off the water to the house at the water main. Then, open a faucet somewhere in your house to relieve the pressure from the system (this is an essential step; if you don't do this, later on when you're putting on the epoxy to plug the leak, the pressure in the system will cause the epoxy to bubble and you'll be back at square one).
To plug the leak, I use epoxy; this is a glue-like substance that is about as strong as PVC when it cures. You can find many different kinds at Home Depot, I've been using the Loctite brand (for some reason I've been using the marine epoxy, which is supposed to be able to cure under water; I don't really think it's necessary though. Any old epoxy should be fine).
Take some sandpaper and buff the location of the leak; this will create a better surface for the epoxy to adhere to. Then, mix your epoxy and spread it over the leak. You'll need to wait several hours (even though it says it sets in 50 minutes, you'll want to wait at least 3-4 hours, possibly more; if you turn the water back on too soon, and the epoxy is not hard enough, the pressure will punch a hole right through and you'll be back at square one, again).
And that's it, no need to call a plumber! Make sure to pick up any standing water with a wet/dry vacuum, and possibly bring in a dehumidifier to suck up any excess moisture (to prevent the growth of mold).