A few things before you start:
First, we've found Family Handyman magazine to be well worth the cost of a $12-$20 annual subscription. They're either teaching you how to do things you never knew you wanted to do, or showing you the cool new tools that you never knew you needed, or helping you decide what you have no interest in doing.
Second, here's some soldering links to get you going:
The Family Handyman Magazine: Keyword Search Results
Third, more than you ever wanted to know about replacing water heaters:
The Family Handyman Magazine: Keyword Search Results
Fourth, if you're still with us and if your family/roomates aren't standing around hoping to get a hot shower within the next 24 hours, then you could experiment. I hate the performance pressure of breaking into a pipe at 8 AM and having to be done by 4 PM (including trips to the hardware store). But if you're patient, and especially if you don't mind a day or two of cold showers, then this job is well within the capacity of a first-time DIYer.
Fifth, see if your local utility company has a rebate for high-efficiency water heaters. I don't know if gas is cheap in your area-- if it is then no one may want to pay you to buy a high-e heater.
Sixth, considering the heat you went through in your attic-insulation project, does your area offer solar water heating? Again if gas is cheap then this may not be worth the payback. But if you're going this route then all you have to do is find a solar contractor, and installing the new water heater (special models for solar systems) will be part of the job.
I've never bothered with a permit for a water-heater repair. I'm not sure that it's even necessary.
Some nanny states have incredibly detailed code specs for mounting gas water heaters-- off the floor to avoid gas accumulation or exposure to other flammable vapors, strapped to the wall in case of earthquakes or hurricanes, exhaust duct draft requirements, enclosed in a pan with a separate drain in case the shell leaks, and so on. The code might be more recent than your old heater, and it's worth checking your local newspapers or websites to see if there's any discussion of how to mount the new heater. If it's not done correctly then you'll have problems passing the home inspection when you sell the place.
You can drain the water from the pressure-temperature relief any way you want. What's there now is just intended to keep the relief from making a mess if there's a problem. Ideally the water never gets hotter than about 180 degrees, so the PVC will probably be fine-- they usually print the temperature limits on the piping.
Gas piping is very low pressure and hard to detect a leak, yet you really don't wanna screw it up. Use the soapy leak detector after you reconnect the joints.
When you're done with the heater and you've turned the water back on, leave the piping insulation off for a day or two in case you have leaks. After that waiting period, give all the joints one more torque before you hide them behind the insulation.
Are you sure about that? I saw the handle as well and thought I could unscrew the flex connector rather than cutting off the valve. But looking at it again, I wasn't sure if the flex connector could be unscrewed from the valve, or if it was sweated or permanently attached some other way.
That solder looks kinda ugly. You could shut off that cold water valve, open a hot water valve to bleed off the residual pressure, put a wrench on the hex nut, and see what happens with gentle torque. You might need a second wrench on the valve to counter-torque it against the flex (and to avoid breaking the solder joint between the valve and the copper pipe of the supply line).
Also, someone installed black foam insulation on the cold water pipe. I understand the insulation on the hot water line, but is there any reason to put it on the cold water supply line?
Not unless it feels warm to the touch. Some water heaters have thermal isolation fittings where the cold water enters the heater to keep hot water from heating the cold-water supply pipe. But a plumber figures that insulation is cheap and it keeps ignorant homeowners from thinking that they're not using enough of it.
Other things that I wish I'd known before I started a water-heater job:
- First and foremost, shut that cold-water isolation valve and make sure it does not leak before you disconnect any other gas or hot-water piping. You don't want to have to shut off the house water as well as the hot water.
- You're going to appreciate having two Ford (pipe) wrenches, each at least 12" long.
- You're also gonna appreciate having an equipment dolly and a ratchet strap (or strong rope) to rassle that water heater out of its hole and to get the new one in.
- Get a firecloth for soldering near the walls. The traditional (cheap) ones look like woven asbestos fibers but the modern (more expensive) ones look cool and are even easier to use.
- Depending on how close those pipes are to the wall and to each other, you may need a compact rotary pipe cutter. The regular ones are about 5-6" long but they make them as tiny as 2". Far better than a hacksaw of last resort.
- If you happen to remove that clamp/wire from the cold-water supply pipe, be sure to verify good contact with the bare piping when you put it back on. That's a grounding wire, and hopefully you won't have to mess with it.
- Before putting in the new heater, groom its anode rod. Buy a deep socket head to get the anode rod out of the heater. The socket will probably be something like 1&1/16" on a 3/8" drive, which means you may also need a 3/8" drive socket wrench. (You might even need a 2-3' iron pipe to slip around the end of the socket wrench for a torque assist.) Before you install the new water heater, unscrew the anode rod, wrap Teflon plumber's tape around the threads, and reinstall it. You'll be checking it every 2-3 years depending on your water conditions, but consider taking pictures/measurements of the anode rod for the day 3-5 years from now when you have to replace it.
- Buy extra copper pipe, fittings, and flex piping. You'll probably be returning it later but it's cheap insurance against the inevitable mistakes. You might even want to buy extra extra supplies for soldering practice.
- Soldering is 99% tedious prep work and 1% [-]fun[/-] flame. Clean the pipe ends with fine-grit sandpaper or steel wool before putting on the flux. You want the pipe as clean & smooth as possible before you put on the flux & solder or you'll inevitably get a leak and have to start over.