How to Buy a Hot Water Heater
There are two main types of water heaters: those that have an insulated storage tank to hold hot water until it is needed, and those called tankless, which only heat the water as it is needed. Tankless models tend to be more energy efficient but have lower throughput than models with storage tanks. Throughput means the amount of hot water produced in a given amount of time.
Both types of water heaters come in versions powered by electricity, natural gas, or liquid propane. Electric models cost the most to operate and are the least energy efficient.
Solar water heaters are starting to gain traction in the marketplace. They come in both passive and active configurations and can use several different types of collectors. Currently, solar water heaters are more expensive than other options but are typically cheaper to operate. Solar water heaters depend on line of sight access to sunlight, so carefully evaluate the installation site with a professional before committing to solar.
Water Heater Brands
Water heaters are made by a wide variety of heating and cooling (HVAC) companies, including:
Capacity and Throughput
Capacity is an important factor in choosing a hot water heater. Estimate water usage during the heaviest hour of a typical day and ensure the FHR (first hour rating) of the heater is close to that number. The FHR is closely related to the power output or BTU of the unit and is an indication of its peak throughput.
Tankless heaters generally produce 3.5 gallons per minute. Heavy users will likely find this insufficient. Licensed plumbing contractor Jack Gill doesn't recommend tankless hot water heaters for daily use and cautions that homeowners with tankless heaters likely "won't be able to do the dishes and take a hot shower at the same time."
It is also important to measure tank sizes and the available space in a home. It does no good to purchase a high capacity heater if it doesn't fit into your space. It is also possible to extend plumbing lines to a different location, but that can greatly increase the installation costs.
Another factor to consider is the material used to construct the storage tank in units that use them. Stainless steel tanks are expensive but do not rust. Steel tanks coated in ceramic or porcelain are also corrosion resistant, except if they become scratched or dented. Tank corrosion can require replacing the entire unit, while problems such as leaky valves or worn out electrical elements can be fixed with replacement parts
Water Heater Warranties
Many water heaters come with long warranties (anything from 6-12 years) but the majority of the warranty period only covers defective parts. For example, GE water heaters come with a full replacement warranty for the first year and a defective parts warranty for an additional 5, 8, or 11 years. Many other brands structure their warranties in a similar manner.