Enamel Spray Paints
A quality enamel spray paint is probably the easiest and least expensive option. Enamel spray paints are not as long-lasting as lacquer or appliance epoxy, but they help prevent rust. And because they come in a multitude of colors, two finishes (matte or glossy) and are made by a number of manufacturers, they offer significantly more options for matching existing wallpaper or paint.
If you use appliance epoxy, you must choose a heat-resistant form. Your color choices might be more limited, but this kind of paint is likely to last much longer than enamel or lacquer. Because it maintains its color and finish when scrubbed cleaned, it is perfect for high-traffic areas, such as children's rooms. You can apply appliance epoxy with a brush or a spray, but, because of its viscosity, you will likely need more appliance epoxy spray than enamel or lacquer spray paint to cover the same area.
A good lacquer will provide a high-gloss finish, is fairly heat-resistant and dries very quickly. You can brush on lacquer or use a spray for easier application. Lacquer does not offer as many color options as enamel spray paint but does have more color options than appliance epoxy. Although lacquer is usually more durable than enamel, it does not provide the same rust-proofing benefits. And because of its sensitive glossy finish, lacquer is more difficult to clean. If you anticipate cleaning your heaters more than once every couple of months, you may want to apply a good sealant over the lacquer or choose another option.