The size is fixed, at 40 gallons and it is natural gas.
I expect to be here awhile and I live in a condo where the heater is in a large closet just off the living space, so durability is paramount. I don’t want to come home one day to find my living room flooded.
I notice you can buy glass, stainless steel, or stone lined heaters now (In the past all I recall was glass lined, but maybe I wasn’t paying attention).
Anybody with experience with this choice?
If you’re worried about floods, buy a tankless water heater. Mine is nearly maintenance free. They’re not cheap to install, though. Or go with point-of-use water heaters.
Some Gas Utility companies offer this service & you can pay for the unit over time on your gas bill. Back in the day, the one I worked for couldn’t charge interest on the balance, just a late charge if you payed your bill late.
I’ve seen some models offered to be installed ‘same day’ or ‘next day’.
Always get three quotes, but get a quote from them if they are allowed to sell them in your area. Can’t hurt to get a quote.
Might not work for a condo.
I’d stick with the tried and true water heaters, like you have. Easy to install and not too expensive. Can be a DIY project, but be real careful with the gas. If you have any qualms, hire a licensed plumber. Home Depot units are fine, and they are rated so you can pick the quality/price point that suits you best.
The OP might not have enough gas capacity in a condo to support a tankless water heater. They require lots of fire very fast. But it’s worth checking out, if you’re willing to spend the money.
If you’re worried about floods, put a drain pan under the heater when you install the new one, with a line to the drainpipes.
Water heaters typically don’t give out and leak for many, many years - 10, 20 or more. Any good model should outlast your tenancy. Go for rapid heating and fuel efficiency over other worries.
It’s a relatively simple DIY job, but you might want to schedule your gas company to stop by and check the gas line, burner and so forth when you’re done. Most will do it free. Between 'splosions and CO, gas-fired appliances in living spaces are not to be trifled with.
I would have someone put it in for you especially since you live in a condo.
If you’re about another condo or basement and something goes wrong you may liable for any damages .
…concur. Good point.
One issue with DIY is the placement of the heater. It is in a very tight space (condo, remember?). I am too old to be contorting myself like that, and getting the old one out and the new one in is a two man job.
Also, my version of DIY generally entails doing it wrong the first time ("Oh, that’s how I should have done it!). I don’t think that’s appropriate when gas is involved.
Ah, no problem. The leaks will suppress the fire. 
Like I said, if you have any qualms, hire a licensed plumber. Buy the unit yourself, and you won’t have to pay his mark-up on it.
Sears used to be famous for that. They guaranteed call by noon, get a new heater installed the same day. When my 30-year old Kenmore dumped its load a couple of years ago, I called Sears. Seems they couldn’t come out for four days. So I called Home Depot at 8:00 am on a Saturday and I was taking a hot shower before noon the same day.
Home Depot used a contracted plumbing service. I’m sure I could have had it installed the same day if I had called any number of plumbers directly.
My advice is just go with a reasonably-priced heater and if you see any leaks around the area, get it replaced immediately. I saw bits of leakage for a few months. It was a little bit and it didn’t leak every day, so I just put off dealing with it. Then one night, I heard “glug, glug, glug” and all the water just dumped out.
As Amateur Barbarian wisely said, install a drain pan if you are concerned.
They sell three levels at home depot and I’d recommend the high level one. One nice feature is it has a sensor that detects leaks, plus you can hook it up to wifi, there are a number of other features as well.
Water heaters: *There’s an app for that!
*An egregious case of Carlin’s Law, IMHO.
I have a plumber that I’ve always used. I had to replace a hot water heater so I called him and told him the size I needed. He came and installed it. Yeah, there’s a mark up, but it wasn’t that much, and I didn’t want to mess dickering with things in Home Depot or Lowes and getting them delivered. My time has a value to me. I have friends who are handy and installed one themselves. Good for them. I’m not handy, and I know my limits.
In many areas you need a permit to replace a water heater. If that’s the case where you live, it kind of eliminates DIY. In the county where I used to live, the inspectors would cruise around on trash day and look for old heaters at the curb. When they found one they’d knock on the did to see your permit.
Had mine replaced a few years ago. Picking the right water heater was the easy part. Even when the installer looked at the exhaust pipe and said “this isn’t up to code anymore” I thought I could get off easy. Another guy, the county inspector, the first guy and the inspector again and then I was allowed to have hot water. I’ll do it myself next time.
I sell water heaters. I recommend Bradford White, made in Michigan and they have a very small failure rate. Check out a local plumbing supply place or Ferguson (locations nationwide)
Ignore all the reviews you see online for any brand of water heaters, they are invariably from DIY’ers who fucked up their install or incompetent wannabe plumbers.
A couple points;
-NAECA standards were strengthened April 15th 2016 so your new heater is going to be ~2" wider than the old one.
-Like GaryM said, make sure you get the permit if you need it, not getting the permit is way too big of a risk.
-re: tankless, while they are better than ever before I’m still not sold on them, especially here in Chicago or similarly cold zones. Install is tough, all the lines need to be insulated, and you need to install a set of isolation valves so you can flush and clean the system once per year.
You also need to consider your gas line. With a standard chimney 40KBtu WH, a 3/4" gas line will be sufficient. With a tankless system you are looking at ~199K Btu, and you’ll probably need to run 1" from the main service to the heater. Not too big a deal in a house, kind of a deal breaker in a condo.
That’s required by code, so if a licensed plumber does the work, he or she should automatically include that.
Just because you need a permit doesn’t mean you can’t DIY. You just have to pass the inspection for code compliance. The inspector will not even know who did the installation.
Good info in this thread. We are going to replace our 18 year old water heater soon. There are no problems with it, but it’s age is prompting me. It is on a pedestal in our garage so no issues with replacing it with the same thing. Copper lines - so will look into what MikeG says.
Slight tangent: I am highly considering adding a hot water circulating pump at the same time (we are in CA and looking to save water). Any opinions on those?