Dont' buy the gas hot water tank. Rent it. You don't need heating everyday. But you need hot water everyday. If you own it, it borken. It may take you 3-5 days to make an appointment to fix it. Replace one is more trouble. You rent it, it has problem, just call them. They usually come in next day and they know the model, they have parts with them. It takes 1500 for you to buy and install a gas water heater about 7-8 years rent. It may last 10-12 years. The saving would be wiped out if there is one for two repairs. The rental compay they buy it cheap and has technician as employee. That is how they make their money.
If you want to own, own electric one. If something goes wrong, buy one for 500 dollars and install it in few hours. Ask them to setup right the first time for easy replacement. But you pay about 20 dollar more electricity which is about same as gas hot water rental.
So in most case, people buy the gas furnace and rent gas watertank.