Have your heating system inspected and serviced by a professional. Call the company that sold it to you or your fuel distributor to get recommendations for servicers.
Blanket the water heater
Get one of those nice, fat insulating blankets for your water heater if it doesn’t have one. You don’t want to pay to heat all that water and then let the heat leak into the atmosphere.
Inspect and maintain the water heater
Have your water heater professionally serviced once a year. (Keep track with this furnace maintenance record from the University of Alaska Fairbanks Cooperative Extension Service.) Inspect the water heater thoroughly and check the walls and floor around it for evidence of leaks, rust or corrosion. Also check the lines and connections to the heater. Even a small amount of moisture can rot the flooring and subfloor. Lie on the floor to look at the bottom of the heater from underneath, using a flashlight. If you find leaks, replace the water heater.
Test the valve that controls temperature and pressure on tank-type water heaters. Do this once a year because, if the valve becomes stuck in the on or off position, an explosion can result. Work carefully because the water in the tank is extremely hot. Do it during business hours on a weekday so you can get help if you find problems. Put a bucket under the water heater’s overflow pipe to catch the drainage. The valve is at the top of the water heater and is recognizable because it has a small handle. Lift the test handle for five seconds to release a little water, then close it. If the valve refuses to close, or if nothing comes out, call a plumber immediately to replace it. (See an illustration and detailed instructions in this pamphlet by the Washington state Department of Labor and Industries.)