While we're on water heaters, this is a good time for one to think about removing and, if need be, replacing your water heater anode if yours has one. A deep socket may work. Different makes and models use different sizes and alloys, so confirm you're getting the right one. As with your household water heater, it's a form of cathodic protection, sacrificing itself by corroding before other tank components do so. And while the old one is out, turn your water on to flush out calcium and other debris. Stick the palm of your hand against the opening for a minute, then pull it away and step back. The air you just pressurized in the tank will force the water out like it does in the powerful toilets with a pressure tank, carrying debris out with it. Repeat until you don't feel any more grit in the bottom of the tank. When installing the new anode (or old one if still OK), use Teflon tape or equivalent and tighten per specs in manual which may be more than snug; tight, but not like a lug nut or something. If you're not preparing it for winter, refill tank, turning on a hot water tap inside until excess air is removed. That will still leave the top of tank with a column of a few inches of air it must have as a buffer to the expansion of heating water in these small, closed systems. That air column may disappear in time if leave system pressurized long enough and don't partially drain the tank or at least open the pressure relief valve lever for a minute while the system is not pressurized. And, check your manual as newer equipment than I've dealt with may vary recommendations somewhat.
