Seal off laundry room. Washers and dryers generate large amounts of heat and humidity. When possible, use them in the morning or late evening when you can better tolerate the extra heat. Seal off the laundry room when in use, and duct or vent the air to the outside of the house. Insulate water heater.
Water heaters radiate heat which can be easily contained by insulation.
Be sure not to cover any vents. This simple technique will also greatly increase the efficiency of your water heater, resulting in lower energy bills. Many homes with central heating have ducts which run through the attic and crawl space. If the seams in these ducts are leaky, especially in the attic, they can draw in hot summer air which flows into the house, creating more of a load for air conditioners. Minor duct repairs are easy to accom plish, and usually involve folding or crimping the tin edges with a pliers.