In the course of installing my new central heating, the installer discovered that my water heater is not firing up correctly -- the flame "rolls out" after a 2-3 second delay, and he says that's not safe.

So, it looks like I'll probably be replacing the water heater.

Any recommendations on what to replace it with? The current heater is 40 gal, I wouldn't mind going to 50 gal. It's natural gas-fired, and I'd prefer a "shorty" unit rather than full height.

Thanks for any suggestions.