Water Heater Buying Guide

Heating water accounts for up to 30 percent of the average home's energy bill, but before you pay $500+ for a new storage-tank heater or up to $1,200 for a more-efficient tankless model, make sure your old water heater cannot be fixed; for example, the storage tank is corroded and leaking. If, however, your only problem is a leaky drain or pressure-relief valve or a worn-out electric heating element, consider having the water heater fixed if the labor cost is reasonable. If not, use that money towards a new unit - especially if your old one's warranty is expired. Gas vs. Electric If you have a choice between gas and electric, consider gas - they're typically more powerful than electric units, more energy efficient, and will save money over the long run. Important gas installation points are venting, proper gas line sizing, and combustion air requirements. Electric models usually have high amperage requirements, but no combustion air or venting requirements. Water Heater Fuel Considerations from Home Depot. Gas:

• Requires a slightly larger up-front investment
• Must be vented outdoors for safety
• Units with sealed combustion or power venting increase safety
• Usually cost less to operate
• Not affected by power outages (tank-style only)

Electric:

• Generally, cost less than gas models
• Easy to maintain
• Requires no combustibles or venting
• Heats water quickly
• Offer high energy factor ratings

Energy Efficiency Whichever fuel you decide on, a water heater is an energy-hog, so you'll want to consider an energy-conserving model. Fortunately, most water heaters nowadays offer increased efficiencies and units have Energy Factor (EF) ratings - a measurement on how efficiently that unit converts energy into heat and how much heat is lost during storage. The higher the EF, the more efficient the water heater is - a rating of 1 is best. However, don't choose a water heater solely on it's EF - you need to consider other factors, such as the fuel type and availability, the water heater's size, and additional costs, such as installation. Follow the advice of the US Dept of Energy when determining the energy efficiency: - for a Conventional Storage and Tankless Water Heater - for a Solar Water Heater Most Common Types of Water Heaters

• Storage Tank Water Heaters Most storage tank water heaters are steel cylinders that have at least the following:
  • an internal tank fed by a "dip tube" with a shutoff valve,
  • a pipe at the top of the unit where the hot water exits,
  • a pressure valve also at the top of the unit,
  • a drain at the bottom of the unit to be able to empty it,
  • a control unit where temperatures can be set.
  For gas models, the pilot light valve is near the set of controls. If you already have gas hookups in your home, it's the fuel of choice. Although gas water heaters tend to cost more up front, they'll cost you less over the long run compared to electric units. Things to Consider
  • Most storage water heaters are sold using capacity, but it's the first-hour rating (FHR) that's more important - this number tells you how much hot water the heater can deliver in one hour of use. To determine how much hot water your family needs, figure your water usage based on the busiest hour on an average day. You can do this by guessing how many gallons is used for daily routines, like shaving, washing, showering, cooking, cleaning, etc. - also, factor in wheter you have children or other water needs. The number you come up with should meet or exceed the FHR number on the water heater' yellow EnergyGuide label. Or try Consumer Reports online sizing calculator for storage tank water heaters.
  • Look for a longer warranty; water heaters with the lowest and highest warranties differ by a relatively small dollar amount, but the inner workings of the longer warranty models are typically of higher quality. You’ll also want a longer warranty if you have hard water and have to use water softeners - softeners speed up the rate of anode corrosion.
  • Measure first to make sure your water heater will fit - insulation can make a unit up to 4" fatter creating problems for small spaces.
  • Consider a gas unit - but remember to factor in the cost of running a gas line to your home if you don’t have one.

  More on storage tank water heaters from the US Dept of Energy. General Maintenance Considerations Every few months, you should:
  • Check the water heater for leaks.
  • Flush out the water to avoid calcium buildup and sediment.
  • Test the pressure-relief valve and the temperature gauge.
  • Inspect anode rods.
  • Read your owner's manual for specific maintenance recommendations.
  Troubleshooting a Water Heater from DoItYourself.com.
• Tankless Water Heaters Tankless water heaters, as the name implies, do not have water storage tanks, so they're smaller than conventional storage tank units. They heat water only as needed by using an electric coil or natural gas to heat water passing through a network of copper pipes. Tankless water heaters save water and energy by heating only the water you need, but they can cost up to three times more than a storage tank water heater and typically require expensive upgrades in gas- or electric-lines and venting. Things to Consider
  • Tankless water heaters do not deliver hot water instantaneously - it takes just a bit of time to heat the water to the desired temperature and, just like storage tanks, cold water in the pipes needs to be pushed out. Also, if you're power goes out and you've got an electric unit, you're out of hot water.
  • There are high up-front costs with tankless units - costs can range from $800 - $1,200, compared with $300 to $500 for conventional storage tank units. And they need electrical outlets for fans and electronics, upgraded or new gas pipes, and ventilation system, pushing installation costs way up.
  • Tankless units typically need more maintenance - pros recommend tankless models be serviced at least once a year; calcium buildup will decrease efficiency, restrict water flow, and essentially damage tankless models. Hard water rated above 11 grains per gallon will require a water softener to avoid damaging the unit.
  • Consider your climate - use the coldest groundwater temperature to calculate the gallons per minute (GPM) you'll need. Unlike a conventional storage tank water heater, a tankless unit's hot water output is directly affected by groundwater temperatures. The same model in a hot climate will not produce the same GPM in a cold climate - this is because the water temperature needs to be raise more.
  • Calculate your hot water usage - use Consumer Reports tankless water heater sizing calculator to figure out how much water you use.
  • Look for rebates and incentives - many tankless models qualify for rebates and state tax credits; check the Database of State Incentives for Renewables and Efficiency.

  More on tankless water heaters from the US Dept of Energy. More on how tankless water heaters work from Consumer Reports. For maintenance, read your owner's manual for specific maintenance recommendations.
• Solar Water Heating Systems Solar water heaters can meet all of a home's hot water needs, but just how much energy can be provided depends on your geographic location and system design and orientation. They are available in a variety of configurations, all differing in design, complexity, cost, and performance, and generally consist of a storage tank, a solar energy collector, pumps and controls, and a back-up source, such as electricity or gas. Types of Solar Water Heater Systems Solar water heaters come in a variety of designs: batch collectors, flat-plate collectors, and evacuated tube collectors - all using the sun's energy to heat water.
  • Batch collectors, also called Integrated Collector-Storage (ICS) systems: Water is heated tanks or tubes within an insulated box, storing water until needed. Water can remain in the collector for long periods of time if household demand is low. A tempering valve, which protects from scalding at the tap, mixes in cold water to decrease the water's temperature before it's delivered. Batch collectors are incompatible with closed-loop circulation systems, therefore not typically recommended for cold climates.
  • Flat-plate collectors: Typically consist of copper tubes fitted to flat absorber plates. The most common configuration is a series of parallel tubes connected at each end by two pipes, the inlet and outlet manifolds. The flat plate assembly is contained within an insulated box covered with tempered glass. Flat plate collectors are typically sized to contain 40 gallons of water - two collectors would be enough to provide roughly half of the hot water needed to serve a family of four.
  • Evacuated tube collectors: These are the most efficient collectors available. Each evacuated tube is similar to a thermos - a glass or metal tube containing the water or heat transfer fluid is surrounded by a larger glass tube and the space between them is a vacuum, so very little heat is lost from the fluid. These collectors even work well in overcast conditions and operate in temperatures as low as -40°F. Individual tubes are replaced as needed. However, evacuated tube collectors can cost twice as much per square foot as flat plate collectors.

  Types of Circulation Systems
  • Direct Open-Loop systems circulate water through the collectors where it's heated by the sun, then stored in a tank for use. These systems are preferable in temperate climates; freeze protection is necessary in cold climates.
  • Indirect Closed-Loop systems use a heat transfer liquid to transfer heat from the sun's energy to water in a storage tank. The heat transfer fluid is heated, then it passes through a heat exchanger in the storage tank transferring it's heat to the water. These systems work well in cold climates.
  • Active systems use electric pumps and valves to move water from the collectors to the storage tank.
  • Passive systems utilize no pumps, instead convection moves water from the collectors to the storage tank as it heats up.

  Installation costs vary, however, an active, flat plate solar collector system will cost approximately $3,500 installed and produce about 100 gallons of hot water per day; a passive system will cost about $2,000 installed, but will provide less hot water per day. How to Size a Solar Water Heater from EERE. Installation Considerations
  • Sun exposure for the solar collectors: The area housing the solar collectors must have good exposure to the sun. A flat roof is ideal to orient the collectors towards the sun; if the roof is pitched, the ideal direction to face is south.
  • The area for the solar collectors: The area necessary will depend on the amount of hot water usage per day, the type of collectors used, the orientation of the collectors and your location.
  • If you choose a passive system, the storage tank will be on the roof of the home and will require structural bracing.

  More on Solar Water Heaters from the US Dept of Energy. Purchasing Tips from ENERGY STAR For maintenance, read your owner's manual for specific maintenance recommendations. Other solar water heating options (from EERE):
  • Heat Pump Water Heaters
  • Tankless Coil and Indirect Water Heaters