Water Heaters
There’s a lot to think about when you select a new water heating system for your home. And in 2010, there are substantial tax credits you can receive for replacing your traditional water heater. You should consider a water heating system that will not only provide enough hot water but that will also save your money and be energy efficient. There are two types of water heaters that you might want to consider-a tankless heater or a solar water heater.
Demand (also called tankless or instantaneous) water heaters provide hot water only as it is needed. They don't produce the standby energy losses associated with storage water heaters, which can make them more energy efficient and can save you money. Through 2010, purchasers of tankless heaters can recieve a tax credit of up to $1500 or 30% of the purchase price. When you take that into consideration, along with the monthly energy savings, the lifetime savings of running a tankless vs. a traditional heater can be substantial.
How They Work
Demand water heaters heat water directly without the use of a storage tank. Therefore, they avoid the standby heat losses associated with storage water heaters. When a hot water tap is turned on, cold water travels through a pipe into the unit. Either a gas burner or an electric element heats the water. As a result, demand water heaters deliver a constant supply of hot water. You don't need to wait for a storage tank to fill up with enough hot water. However, a demand water heater's output limits the flow rate.
Typically, demand water heaters provide hot water at a rate of 2–5 gallons (7.6–15.2 liters) per minute. Gas-fired demand water heaters produce higher flow rates than electric ones. Sometimes, however, even the largest, gas-fired model cannot supply enough hot water for simultaneous, multiple uses in large households. For example, taking a shower and running the dishwasher at the same time can stretch a demand water heater to its limit. To overcome this problem, you can install two or more demand water heaters, connected in parallel for simultaneous demands of hot water. You can also install separate demand water heaters for appliances—such as a clothes washer or dishwater—that use a lot of hot water in your home.
Other applications for demand water heaters include the following:
- Remote bathrooms or hot tubs
- Booster for appliances, such as dishwashers or clothes washers
- Booster for a solar water heating system.
Although gas-fired demand water heaters tend to have higher flow rates than electric ones, they can waste energy if they have a constantly burning pilot light. In a gas-fired storage water heater, the pilot light heats the water in the tank so the energy isn't wasted. The cost of operating a pilot light in a demand water heater varies from model to model. Ask the manufacturer how much gas the pilot light uses for the model you're considering. If you purchase a model that uses a standing pilot light, you can always turn it off when it's not in use to save energy. Also consider models that have an intermittent ignition device (IID) instead of a standing pilot light. This device resembles the spark ignition device on some gas kitchen ranges and ovens.
For homes that use 41 gallons or less of hot water daily, demand water heaters can be 24%–34% more energy efficient than conventional storage tank water heaters. They can be 8%–14% more energy efficient for homes that use a lot of hot water—around 86 gallons per day. You can achieve even greater energy savings of 27%–50% if you install a demand water heater at each hot water outlet.
Selecting a Demand Water Heater
Demand water heaters cost more than conventional storage water heaters. However, you may find that a demand water heater may have lower operating and energy costs, which could offset its higher purchase price.
Before buying a demand water heater, you also need to consider the following:
- Do you use hot water efficiently? Have you installed modern, low-flow faucets and showerheads? Tankless water heaters perform much better when they are partnered with efficient uses.
- Consider your water distribution system. If the hot water uses in your home are relatively close together, with short hot water lines between them, a tankless system may work for you. In many U.S. homes, water uses are widely spaced at opposite ends of the house. If this is the case in your home, a tankless system may not meet your needs.
- If you have installed high efficiency fixtures and your water lines are not too long, consult an experienced contractor like E&M Plumbing to find out if your gas supply is adequate and proper venting is feasible.
- Finally, residential wiring generally will not support a tankless electric water heater with large enough capacity to serve multiple uses. If you rely on electricity to heat your water, a tankless system is unlikely to meet your needs. At most, an electric unit may be appropriate for small applications, such as a remote bathroom without a bath tub.
Installation and Maintenance
Proper installation and maintenance of your demand water heater can optimize its energy efficiency. Proper installation depends on many factors. These factors include fuel type, climate, local building code requirements, and safety issues, especially concerning the combustion of gas-fired water heaters. Therefore, it's best to have a qualified plumbing and heating contractor install your demand water heater such as E&M Plumbing. Do the following when selecting a contractor:
- Request cost estimates in writing
- Ask for references
- Check the company with your local Better Business Bureau
- See if the company will obtain a local permit if necessary and understands local building codes, etc.
Most tankless water heaters have a life expectancy of more than 20 years. They also have easily replaceable parts that extend their life by many more years. In contrast, storage water heaters last 10–15 years. Periodic water heater maintenance can significantly extend your water heater's life and minimize loss of efficiency. Read your owner's manual for specific maintenance recommendations.
Improving Energy Efficiency
After your demand water heater is properly installed and maintained, try some additional energy-saving strategies to help lower your water heating bills. Some energy-saving devices and systems are more cost-effective to install with the water heater. Before rushing out to buy a tankless water heater, be aware that they are not appropriate for every situation. Here are some of the factors to consider:
If you choose a tankless unit, look for a gas-fired model eligible for 2009 federal tax credits, at least an Energy Factor (EF) of 0.80. To learn more about tankless water heaters, call E&M Plumbing at at (636) 938-1311 or go to emplumbing.com.
Solar Water Heaters
Plus, incentives in the sun-belt are making a comeback. The initial cost of a solar water heater is still much higher than other competing technologies, but if you can make the upfront investment (which is easier with tax breaks and rebates), it can save 50–75% of your water heating energy over the long term. Areas that receive sun consistently for 3 or more seasons will not only save more energy, but consumers are likely to have more products to choose from at lower costs. Make sure you find a qualified installer who can properly design and size the back-up water heating system.
Solar Water Heaters
Using the sun to heat hot water is a simple technology that has been around for decades. Solar water heaters—also called solar domestic hot water systems— can be a great investment because they offer a virtually cost-free and renewable energy source for one of your home’s top energy-users. But because the feasibility and benefits of a solar water heater will vary based on a number of variables, such as where you live, which way your roof is facing, and how many people live in your house, it takes some extra savvy to know what your costs and savings will be.
Solar water heaters are much less common than they were during the 1970s and early 1980s when they were supported by tax credits, but the units available today tend to be considerably less expensive and more reliable. They can be used in any climate, and the fuel they use—sunshine—is free.
How They Work
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.
Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.
Three types of solar collectors are used for residential applications:
- Flat-plate collector
Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors—typically used for solar pool heating—have a dark absorber plate, made of metal or polymer, without a cover or enclosure.
- Integral collector-storage systems
Also known as ICS or batch systems, they feature one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water. The water then continues on to the conventional backup water heater, providing a reliable source of hot water. They should be installed only in mild-freeze climates because the outdoor pipes could freeze in severe, cold weather.
- Evacuated-tube solar collectors
They feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin's coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for U.S. commercial applications.
There are two types of active solar water heating systems:
- Direct circulation systems
Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
- Indirect circulation systems
Pumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.
Passive solar water heating systems are typically less expensive than active systems, but they're usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems:
- Integral collector-storage passive systems
These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.
- Thermosyphon systems
Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.
Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a demand (tankless or instantaneous) water heater for backup.
Selecting a Solar Water Heater
Before you purchase and install a solar water heating system, you want to do the following:
Installing and Maintaining the System
The proper installation of solar water heaters depends on many factors. These factors include solar resource, climate, local building code requirements, and safety issues; therefore, it's best to have a qualified, solar thermal systems contractor install your system such as E&M Plumbing.
After installation, properly maintaining your system will keep it running smoothly. Passive systems don't require much maintenance. For active systems, discuss the maintenance requirements with your system provider, and consult the system's owner's manual. Plumbing and other conventional water heating components require the same maintenance as conventional systems. Glazing may need to be cleaned in dry climates where rainwater doesn't provide a natural rinse.
- Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part or two after 10 years.
When screening potential contractors for installation and/or maintenance, ask the following questions:
- Does your company have experience installing and maintaining solar water heating systems? Choose a company that has experience installing the type of system you want and servicing the applications you select.
- How many years of experience does your company have with solar heating installation and maintenance? The more experience the better. Request a list of past customers who can provide references.
- Is your company licensed or certified? Having a valid plumber's and/or solar contractor's license is required in some states. Contact your city and county for more information. Confirm licensing with your state's contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.
Even if you aren’t going to buy a new water heater, you can save a lot of energy and money with your existing system by following a few simple suggestions.
- Conserve Water. Your biggest opportunity for savings is to use less hot water. In addition to saving energy (and money), cutting down on hot water use helps conserve dwindling water supplies, which in some parts of the country is a critical problem. A family of four each showering five minutes a day can use about 700 gallons per week—a three-year drinking water supply for one person! Water-conserving showerheads and faucet aerators can cut hot water use in half. That family of four can save 14,000 gallons of water a year and the energy required to heat it.
- Insulate Your Existing Water Heater. If your electric water heater was installed before 2004, installing an insulating jacket is one of the most effective do-it-yourself energy-saving projects, especially if your water heater is in an unheated space. The insulating jacket will reduce standby heat loss—heat lost through the walls of the tank—by 25–40%, saving 4–9% on your water heating bills. Water heater insulation jackets are widely available for around $10. Always follow directions carefully when installing an insulation jacket.
- Insulate Hot Water Pipes. Insulating your hot water pipes will reduce losses as the hot water is flowing to your faucet and, more importantly, it will reduce standby losses when the tap is turned off and then back on within an hour or so. A great deal of energy and water is wasted waiting for the hot water to reach the tap. Even when pipes are insulated, the water in the pipes will eventually cool, but it stays warmer much longer than it would if the pipes weren’t insulated.
- Lower the Water Heater Temperature. Keep your water heater thermostat set at the lowest temperature that provides you with sufficient hot water. For most households, 120°F water is fine (about midway between the “low” and “medium” setting). Each 10°F reduction in water temperature will generally save 3–5% on your water heating costs. When you are going away on vacation, you can turn the thermostat down to the lowest possible setting, or turn the water heater off altogether for additional savings. With a gas water heater, make sure you know how to relight the pilot if you’re going to turn it off while away.
For more information or for a free consultation, contact E&M Plumbing at 636.938.1311 or visit their website.