Articles

1. Guide to Alternative Hot Water Sources by Daniel Friedmanhow to choose among different ways to make domestic hot water 

ALTERNATIVE HOT WATER SOURCES - CONTENTS: Description of Types of Alternative Hot Water Heating Methods: electric, gas, high efficiency gas, oil, high efficiency oil, solar, tankless coils, instantaneous water heaters, point of use water heaters and other Alternative Hot Water Sources & Methods POST a QUESTION or READ FAQs about alternative ways to make domestic hot water REFERENCESThis article describes alternative methods of providing domestic hot water, comparing the characteristics of various hot water heating methods and describing different ways to heat water for washing and bathing. Whether you make your building hot water using a water heater, geyser, or hot water cylinder, there are alternative methods that can dramatically change the hot water quantity, pressure, flow rate, and operating cost.

2. Alternative Energy & Heating Sources for Hot Water Heaters by Jack Burton

Natural gas or electric water heaters are the standard appliances found in most homes. Sometimes though, alternative sources for heating water are desired. A cabin in a rural location may be inaccessible to utilities, or a plan to simplify a lifestyle requires a reduction in energy use. Several ways exist to provide hot water without natural gas or electricity. Alternative ways may still use a standard water heater tank to store and distribute the hot water, or they may use a custom tank.Solar powerSolar powered water heaters are common appliances and are available in sizes ranging from small and portable for camping out in the woods to a full home-sized tank of water. A standard setup would include solar panels that heat a nonfreezing substance such as glycol, which is then pumped into a heat exchange apparatus which transfers the energy to the water. Most solar systems have a backup propane heat source for extended periods if the sun's energy is not sufficient.Propane GasPropane gas brought in via tanks is the choice of energy for many rural areas. It provides the energy for cooking, and heating the home and water. A large propane tank of 500 gallons may only need filling once a year. A propane water heater is no different than a natural gas heater in operation. Many manufacturers provide a propane-alternative water heater along with natural gas units.Wood HeatWood heat has been pressed into double-duty for warming water since the invention of a bucket to hold water over a fire. For whole house heating, along with enough hot water to even fill up a spa or pool, a dedicated outdoor wood furnace will do the job. It depends on a system of insulated pipes for moving the water from the home to the furnace and back again, with an insulated tank to hold the water until needed.

Creative AnswersCreativity is the only limit to heating water for the home. Geothermal units work by bringing heat up from below the soil level, which is then used to heat the home and water. Some water heaters take advantage of the heat generated by an ongoing composting facility where the temperatures can reach 150 degrees Fahrenheit, while others use a windmill to charge a car battery which heats up the water. Regardless of the method, and no matter how far from civilization you want to be, you never have to leave your long, hot baths behind.

3. Alternative Heating Methods by James Scott

• Solar water heating. This system uses solar energy to heat water. There are two types of solar heating systems: active and passive.• Waste heat recovery units (HRU). This system operates with the central air conditioner or heat pump by recovering heat normally exhausted to the outdoors. As long as your central air system is operating, the extra heat is used to heat water. Installation is about $300-$500, but can save you $100-$140 a year. That's 50% of your home's heating costs!• Heat pump water heater (HPWH). This system extracts heat directly from the air and transfers it to water in a stored tank. The system operates independently of the central air system, so it can produce hot water all year long. Retrofitting an existing water heater can cost about $600-$1000, but it can save you $100-$150 a year.• Demand (tankless or instantaneou) water heaters. This system heats 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.

4. Are Tankless Water Heaters a Waste of Money? by Martin Holladay

Although tankless water heaters are, on average,more efficient than traditional tank-style water heaters, they’re also more expensive — so expensive, in fact, that many potential customers wonder whether their high cost can ever be justified by likely energy savings.Before you can decide whether to buy a tankless water heater, you’ll need to know how much energy you’ll save. Can you trust the information provided by tankless water heater manufacturers — for example, the estimate from Rinnai’s online calculator that you’ll save $178 per year?Before I get around to answering that question in detail, suffice it to say: probably not.Real-world answers from a monitoring studyTo figure out the payback period for the incremental cost of a tankless water heater, it would be useful to know: The installed cost of a tankless water heater; The number of gallons of hot water used per day by the average American family; The in-use efficiency of a typical tank-type water heater and the in-use efficiency of a typical tankless water heater; The annual natural gas savings and the annual dollar savings attributable to switching from a tank-type to a tankless water heater.

To find the answers to all of these questions, a group of researchers in Minnesota undertook a monitoring study to measure the performance of tank-type and tankless water heaters in actual homes. The researchers concluded that most tankless water heaters will fall apart from old age before they save enough energy to justify their high cost.The researchers — Dave Bohac, Ben Schoenbauer, and Martha Hewett of the Center for Energy and Environment in Minneapolis, along with Tom Butcher of Brookhaven National Laboratory and Mary Sue Lobenstein of Lobenstein Consulting — monitored water heaters in ten homes for over a year. Their data have been published in a report, “Actual Savings and Performance of Natural Gas Tankless Water Heaters”.The ten families enrolled in the study were chosen based on household size. The number of people in these families matched the household size distribution shown in the census data for the Minnesota in 2000: two homes had 1 resident each, three homes had 2 residents, two homes had 3 residents, two homes had 4 residents, and one home had 5 residents.A total of twenty-four water heaters were installed in the ten homes; each home got at least two water heaters. Eight homes got a tank-type water heater (an A.O. Smith GCV40 40-gallon natural gas water heater with atmospheric venting). In addition, each home got at least one natural gas tankless water heater. Ten tankless water heaters were tested; a variety of models were chosen from among those sold by five manufacturers (Bosch, Noritz, Rheem, Rinnai, and Takagi). The researchers did not test any electric tankless models.Monitoring equipment for each test set-up included a dedicated gas meter, a dedicated water meter, and temperature sensors that measured the temperature of the incoming water as well as the temperature of the hot water. (The incoming water temperatures varied seasonally by about 30°F to 35°F.)At each house, researchers adjusted gas and water valves to alternate between the tank-type water heater and the tankless water heater at monthly intervals. Only one water heater was used at a time. The changeover schedule was adjusted at each site so that every tested heater operated over the full seasonal spectrum of incoming water temperatures and outdoor air temperatures. An average of 363 days of useful data were collected from each home.

5. Tankless Water Heater or Storage Type? By Bill Lund

Tankless water heaters sales have been booming lately.  Unlimited hot water and energy savings are the features most often touted by the tankless water heater industry, and a smaller footprint is often mentioned.  While they do provide an unlimited supply of hot water they are not without their own problems.Storage type water heaters have been the standard in the United States, but recently tankless water heaters have begun to make an impact.  Most people are familiar with storage (tank type) water heaters, where you have a big tank of hot water ready and waiting when you need it.  The water can be heated with gas flames, electric heating elements, or any other method. Storage or tank type heaters have two potential problems, the first, is they use more standby energy than tankless water heaters, and the second, you can run out of hot water.Tankless water heaters have some drawbacks to them as well.  For one thing, tankless water heaters have a flow switch in the water line that turns them on when sufficient flow is detected.  Usually a flow of about ½ gallon per minute or more is required to turn the unit on.  This pretty much eliminates the idea of having access to a low-flow stream of hot water for anything.

Sometimes it can be difficult to fill a bathtub with a tankless unit.  With tankless heaters, higher the flow rate of the water the lower the temperature rise since the water spends less time in the heater.  With a bathtub you usually turn on the water full blast so it doesn’t take too long to fill the tub.  Usually the faucet at the tub will have the highest flow rate of any fixture in your home, often 7 gallons per minute or more. With typical tankless heaters you end up with a tub full of tepid water.  If you try to fill it more slowly to get it hotter, it takes so long to fill that it cools off before you get in anyway.  So if you like to soak away in a hot tub, you better make sure you get a big enough heater to handle the job.Tankless heaters are substantially more expensive than storage heaters, and more complex, so they are more expensive to repair should anything go wrong.  They also need larger flues and if they are electric, they often need special extra heavy wiring.Another problem with tankless units is that they take longer to get hot water to the fixtures.  That means you waste more water, which is not very environmentally friendly.  The reason is that when you turn the hot water on, the flow switch turns on the heater, and it begins to heat the water.  But to reach full temperature the water must travel through the entire heater.  Now you have to not only dump out the cooled off water in the hot water piping, but also the cooled off water in the water heater as well, before you get hot water at the fixture.Hot water circulating systems do not work with tankless heaters because either the flow of hot water won’t be enough to turn on the heater, or it keeps the heater turned on all of the time.  Neither scenario works. However, there is a way to solve the long wait and wasted water problems.A demand hot water system will work with tankless and with storage type water heaters, providing the benefits of faster hot water delivery and eliminating the running of water down the drain.The demand hot water pump installs at the furthest fixture from the heater, and connects to the hot and cold water lines.  When you want hot water you press a button and the cooled off hot water in the hot water piping gets pumped back to the inlet of the heater, and when the actual hot water reaches the fixture the pump shuts off.  That way you get your hot water faster than running the faucet, you don’t run any water down the drain while you wait, and you don’t fill the cold water line with hot water.  You save time, water, and money.  Typical savings can amount to over 15,000 gallons per year for a family of four. A hot water demand system used with a tankless water heater makes a great environmentally friendly package, saving both water and energy. Demand systems work just as well with storage type water heaters, and if you are considering such a system, you might check with your water company as some offer rebates for such systems.  Be sure to check the pump is powerful enough to turn on the flow switch, as not all pumps are strong enough.  Metlund manufactures several models of demand pumps, at least one of which will run a tankless heater.  Chilipepper Sales also manufactures the Chilipepper appliance which has a pump strong enough to run any tankless heater.If your primary concern is having unlimited amounts of hot water and you can live with the few drawbacks, then the tankless unit is for you, otherwise you might want to stick with a good old-fashioned storage type water heater.

6. Reduce Your Energy Bills with a Solar Hot Water Heater By Bob Ramlow 

How would you like to have free hot water for the next 40 years? That should sound pretty good — about 15 percent to 20 percent of a typical household’s energy outlay goes to make sure the “H” tap means what it says. If energy prices increase by 6 percent annually, the average family would save thousands of dollars over the coming decades by installing a solar hot water heater that supplies just 65 percent of their hot water.I mean “free” literally. Yes, you’ll spend money up front to install the heating system, but your home equity will increase instantly, often enough to offset the cost of installation. You’ll also pay reduced utility bills — saving more money every time rates rise. Within a few years, you’ll recover the initial expense. Experts agree, a solar hot water heater is far and away the easiest initial investment in renewable energy. Perhaps best of all, you’ll enjoy hot baths or showers with the satisfaction of knowing the energy comes directly from the sun.A Good Deal, Getting BetterSolar hot water heaters vary in their details, but they all do the same basic things: gather heat in a solar collector; transfer the heat, directly or indirectly, to the water supply; and store the heated water until it’s used. They use relatively simple, time-tested technology, which is one reason they are a best bet in renewable energy.It’s important to understand that solar water-heating systems have very low — sometimes zero — operating costs, and maintenance amounts to only about $2 per month. Say you might spend $7,000 to install a solar water heater, when you could install a conventional gas or electric heater for considerably less. But it’s so much less expensive to operate the solar heater that, at some point, you’ll make up the initial difference. When all costs for purchase, installation, maintenance and operation are taken into account, a solar water heater usually equals an electric heater after just eight and a half years, and equals a gas heater in just less than 15 years. From then on, through the expected 40-year life of the solar system, you’ve got free hot water (see Image Gallery).Consider the positive environmental benefits of a solar hot water heater, and the deal just gets better. A typical residential solar water heater will offset greenhouse gas emissions by about 1,500 pounds of carbon dioxide (CO2) per year. That’s equal to the amount of CO2 released by an average vehicle every 1,685 miles (based on 19.6 pounds of CO2 per gallon at 22 mpg).It’s cheaper to conserve energy than to purchase it, so the first thing you’ll want to do is reduce your hot water needs to the minimum. Start by reducing waste; then minimize consumption. Reducing your usage ensures that your solar heating system will provide the maximum possible portion of your hot water. Even if you don’t go solar, using the minimum necessary hot water is good for your wallet and good for the environment.

7. Alternative Water Heating Solutions by Marcus

Those who choose to live off the grid are no stranger to hard work, but there are always new projects around the homestead that can substantially increase your quality of life while simultaneously saving a lot of money. Some estimates conclude that heating water is responsible for almost 30 percent of any given family’s energy budget. There is just no reason to pay for that service when several alternatives—such as solar water heaters—can heat enough water for personal use. For those of you who have already installed solar water heating systems and use

electric circuits as a backup heater, there are some cost efficient ways to increase the effectiveness of your solar water heating system.In addition to the (substantial) monetary incentives to begin using a solar water heating system, there are, of course, environmental benefits. If you switch to a solar water heating system, your use of non-renewable resources will drop significantly; that number will approach zero rapidly if your backup heating system is a woodstove or firebox rather than occasional use of a conventional, coal powered system.Gas tankless water heaters are technically “cost-effective” alternatives to conventional water heating systems, but they are hardly worth the investment. Consumer Reports indicates that it can take over 20 years to break even because the installation cost of a gas tankless water heater can be so high. Other tankless heating options present similarly high installation costs, with a period of quite some time to make that money back in savings. By far the cheapest option, solar water heating systems present their own challenges. Namely, not all solar water heaters can heat water quickly enough to meet your water needs; however, switching to a solar water heater would be a great incentive to cut down on your water usage.There are different ways to construct homemade solar water heaters, each tailored to your lifestyle and the type of work you are willing to put into the initial process. Depending on location, altitude, and winter temperatures, not every home will be able to run entirely on a solar water heater because the hot water storage unit will be unable to sustain a sufficiently high temperature 24/7. If you live in an area where you are unable to use a solar water heater to meet all of your energy needs (or it is not an option for most of the winter) solar water heating systems can still be great investments. At the very least, it is a cheap alternative to conventional water heaters for the rest of the year. More likely, you will be able to utilize a solar water heating system at least during winter days (though it is less likely that you will get much return in the evenings or at night) when your solar collector is able to warm up enough to heat the water.

8. Tankless water heaters can lower energy costs by Ann Hoke

Whether you plan to buy or build a home, renovate the one you’re living in now or replace an aging water heater, you may soon find yourself thinking about hot water. Don’t wait until it’s too late to look ahead and consider the options to conventional water heaters.With the increased focus on energy efficiency in homes, it makes sense to find ways to lower our use of energy and lessen utility costs. One alternative is a tankless water heater.According to Energy.gov, tankless or demand water heaters use 24 percent to 34 percent less energy than conventional storage tank water heaters. Energy Star estimates that a typical family can save $100 or more per year with a qualified tankless heater.Tankless systems have gained popularity in Europe and Asia, but have not been as readily adopted in the United States. Cost could be a factor — tankless heaters cost significantly more than a conventional system. But it also could be a matter of educating the American market about the product.Unlike a traditional tank that heats a reservoir of water 24 hours a day, a tankless unit activates only as needed. When there is a demand for heated water, cold water travels through the tankless unit, where a gas burner quickly heats it to the preset temperature.Let’s take a quick look at the pros and cons of both systems so you can form your own opinion.Conventional storage tanks run on electricity or gas, cost less and are fairly simple to install; replacement is not too difficult or expensive when their useful life is ended (usually 10-15 years).

Over the last few years, aggressive efforts on the part of manufacturers have led to increased energy efficiency and certification by the Energy Star program.Tankless units cost more, but have a life expectancy of more than 20 years. They save even more energy because the unit only operates when there is a demand for hot water, which can reduce its energy cost by about 25 percent annually.If a unit is sized properly, a gas tankless heater can deliver a continuous supply of water at a preset temperature (plus or minus 1 degree) at a rate of typically 2 gallons to 5 gallons per minute. The units never run out of hot water, though the flow rate may be inadequate during times of peak demand. The compact size of a typical unit is extremely small, mounts on the wall and takes up considerably less space than a conventional tank.So, to keep myself out of hot water, I’m not going to make a recommendation. I will leave that up to you. Hopefully you will do your homework and make the best decision to fit your lifestyle and budget when the need arises.

9. Save Money By Using an Alternative Hot Water Source by Laurence Pharoah

Water prices are in all likelihood the last thing in our minds when showering or taking a bath. Cleaning the dishes and doing the laundry are also not the time. Heating water is something any family will need to do in one form or another. Almost all water heaters are either electric or natural gas, and their prices are rising regularly. A sound substitute for heating water is to utilize solar as your energy source. The advantage of this is lower energy bills and the fact that you use less energy.

So if solar becomes your choice for heating your water, you still have plenty to think about to make it happen. Do you decide on a pro to install your energy-efficient hot water tank? A second choice is to purchase a solar hot water kit and set it up yourself. The DIY Hot Water Manual, which will demonstrate to you how to make everything yourself, is another choice. Money and time constraints are a consideration with this, and also how confident you are to do it.

10. Tankless water heater technology and energy efficiency

A tankless water heater is usually more energy efficient than a storage tank water heater. It eliminates the continuous standby energy loss of a storage tank.Tankless water heaters are rated with an energy factor (EF): the higher the EF, the more efficient the water heater.Gas tankless water heaters have EFs that range from 0.64 to 0.98, with an average of 0.85. Gas storage tank water heaters have EFs that range from 0.53 to 0.70, with an average of 0.62.Gas tankless water heaters have the capacity to supply hot water for most houses.Most electric tankless water heaters cannot supply an entire house with hot water. They are most effective when installed as supplementary heaters near bathroom or kitchen sinks far from the main water heater. They are also useful in locations with few fixtures and less demand for hot water, such as in a workshop or cottage.

11. Water Heaters by Bob Hamilton

Canadians use an average of 75L of hot water each at home every day—for washing dishes and clothing, cleaning and personal hygiene. For the average family, that adds up!Water heaters account for 17 percent of the energy consumed in the average Canadian home. That share can vary from 15 to 25 percent depending on the house type, number of inhabitants and their lifestyle habits.Commercial water heaters are used in many types of facilities—from the local diner or hair salon to a big hospital or hotel. In Canada, water heating accounts for nine percent of energy used in commercial and institutional buildings. Today high efficiency water heaters use condensing technology which extracts a larger portion of energy from the combustion process. It does this by cooling combustion gasses so they condense on a multi-pass heat exchanger.

12. Combination Systems by Greg Rickford

Some homes simply need less heating. They may have excellent insulation, low air leakage and make efficient use of space. Or they may be located in an area with a milder climate.In these types of homes, a single appliance can do double duty as a water heater and a space heater: a combination system.This type of system usually consists of a fan coil installed with ductwork, and a small pump that circulates water from the water heater through the fan coil. Heated water can also be circulated through in-floor piping to provide floor and radiant heating.Some combination systems use boilers in place of water heaters.Combination systems are not currently regulated under Canada’s Energy Efficiency Regulations. However, look for a system that has been rated as a system using the new Canadian Standards Association standard CSA P.9—Test method for determining the performance of combined space and water heating systems (combos). This test method yields a “thermal performance factor” that consolidates measures for both space heating and water heating.If the system has an energy factor (EF) rating for the water heater only, the energy performance picture is incomplete. The water heater will perform differently when it is in space heating mode.

13. Hot Water Service by Chris Riedy

Water heating is the largest source of greenhouse gas emissions from an average Australian home and the second largest segment of household energy use in Australia, after space heating and cooling. It accounts for about 21% of the energy and generates about 23% of the greenhouse gas emissions (DCCEE 2010). In Australia, about 48% of the energy used for water heating comes from natural gas, 45% from electricity, 3% from liquefied petroleum gas (LPG) and 4% from solar (DCCEE 2012). Electric water heaters in particular contribute to these emissions: only half of Australian homes use electric water heaters, but they contribute 80% of hot water greenhouse emissions. Reducing your hot water use and using renewable energy sources to heat water are great ways to reduce your environmental impact.By installing the most appropriate and efficient water heater for your household size, water use patterns and climate you can save money and reduce greenhouse gas emissions without compromising your lifestyle. An efficient hot water service (HWS) can also add value to your home and help meet state, territory or local government regulations.

14. Water heaters by Geoff Milne

Both of the two basic types of water heater — storage systems and continuous flow (or instantaneous) systems — can use a variety of energy sources to heat water including solar, gas (LPG and natural gas) and electricity.Storage water heatersWater is heated and stored in an insulated tank for use when it is required. These systems can operate on mains pressure or from a gravity feed (constant pressure) tank.Mains pressure — Hot water is delivered at a similar pressure and flow rate to cold water so more than one outlet can usually be turned on without greatly affecting pressure. The storage tank is usually located at ground level inside or outside the house.Mains pressure systems have been the most popular systems in recent decades but heat losses from storage tanks and their associated fittings and pipes can be substantial. Large electric storage tanks and their fittings can waste up to 1,000kWh each year; a typical 5 star gas storage HWS wastes 3,500MJ. This is equivalent to the energy required to heat 50–60L of hot water each day.Constant pressure or gravity feed — Hot water is delivered at lower than mains pressure from a tank located in the roof of the house. Pressure depends on the height difference between the tank and the point of use. Gravity feed systems are most common for older properties and properties not connected to mains water.For either type of system, storage tanks may be made of copper, glass (enamel) lined steel or stainless steel. Copper and glass- lined tanks typically have a sacrificial anode to reduce tank corrosion, which needs to be replaced every few years. Warranties offered for tanks typically range from five to ten years.Continuous flow water heatersContinuous flow or instantaneous systems heat only the water required and do not use a storage tank, so do not suffer the heat/energy losses of storage systems. They can operate on natural gas, LPG or electricity. Gas models are available with either electronic ignition or a pilot flame. They can be mounted externally or internally if suitable ventilation is available.Because continuous flow systems heat the water as it is used, they cannot run out of hot water. Continuous flow water heaters can be fitted with sophisticated temperature controls, including controls that allow the user to set the desired water temperature at the point of use (e.g. in the shower). Water is not overheated and hot water does not need to be diluted with cold water to achieve a suitable temperature, thus saving energy and reducing the risk of burns or scalding.Types of hot water serviceThe main types of water heaters on the Australian market are:

heat pump gas (natural or LPG) — storage or instantaneous solar — electric or gas (natural or LPG) boosted electric — storage or instantaneous.

15. Water Heating: A Smart Place To Gain Efficiencies

Heating water for home use takes a lot of energy—and water heating is one area where it’s easy to make small changes that make a big difference in your energy bill.

Warm showers and baths, automatic and hand dishwashing, and other everyday tasks quickly add up to a lot of hot water usage. In fact, water heating is likely second only to heating and cooling your home in terms of energy use. The average homeowner’s cost of water heating is $400-$600 each year.If you’re like most Americans, your water heater isn’t optimized to save you money, but you can make changes that make a difference. Small changes, like insulating your water heater or shifting to low-flow fixtures, will help to improve performance and reduce waste. Switching from a conventional water heater to an ENERGY STAR qualified water heater may be a good move, potentially cutting your water heating costs in half.

16. Considered the pros and cons by Michael Keenan

Consumers often choose to use the same energy source for water heaters that we use for space heating. This is a preference, not a requirement. It pays to compare water heaters by the fuel types available in your area.

ElectricModels come in a wide array of sizes; need no venting; and are easy to install. They cannot supply hot water during a power failure and take quite a bit of time to reheat.Natural gasModels come in a variety of sizes, types and efficiencies; can be vented through a chimney or wall; and can provide hot water during power failures if they have continuous pilot lights. They require adequate airflow for combustion.PropaneModels have the same pros and cons as natural gas units but propane is a more expensive fuel. Units require a dedicated storage tank and scheduled fuel delivery.OilModels come in limited types and sizes, can be vented through a wall and sealed. They require adequate airflow for combustion, a dedicated storage tank and scheduled fuel delivery; and cannot supply hot water during power outages.

17. Will a "Water-Saving" Hot Water Recirculation Pump Really Save Me Money? By Pablo Paster

Hot water recirculation pumps are a convenient way to ensure that you have immediate hot water from the tap. These systems slowly pump hot water through your hot water pipes and back to the water heater through either a dedicated line or through the cold water line. Several models are available and some claim to save "10,000 gallons or more of water per year" and "up to 15,000 gallons per year" while using "less energy than a 25 watt light bulb." First I will examine these claims, then I will contrast the water saved with the energy used, and finally I will discuss some alternatives.

How Much Does A Hot Water Recirculation Pump Really Save?

Let's look at the calculations on one website:

An average home has approximately 125 ft of 3/4 inch piping. 125 feet of 3/4" pipe holds 3.14 gallons of water. 10 draws per day wastes over 31 gallons of water waiting for the water to get hot. Over a year, the wasted water equals 11,461 gallons.It may be true that the average home holds 125 ft of 3/4-inch piping, although no source was provided for this factoid. But when you turn on the tap, the water doesn't run through all 125 feet. The water runs the most direct course from the water heater to your tap. Also, I would think that half of that pipe is dedicated to cold water. In my house the distance from the water heater to the farther faucet is less than 50 feet. Using their assumptions, the amount of water in the pipe does not come out to 3.14 gallons, but rather 2.8687 gallons.The next assumption is that you draw water ten times per day. This assumes that the water in the pipes cools completely between each draw. In most households however, there are two periods of the day when hot water is being drawn; for the morning shower and the evening dishes. During these periods the water in the pipes would probably not cool down very much so you would realistically only need to wait for hot water two or three times per day.Using the assumptions and calculations from our source, we can confirm that 11,461 gallons would be wasted each year. Using my corrected assumptions, I would put that number closer to 838 gallons. Of course some homes are occupied all day, have a more spread out floorplan, and have a lot more hands to wash. Still, the 11,461 gallons saved are very optimistic. How much money does the pump save on the water bill? Using their savings and California's high water prices you would save around $50 per year, but the reality is probably closer to $4.

Should You Get A Hot Water Recirculation Pump?The pump will cost you $200 to install, $5.50-$32 to operate, will waste $160-$400 per year and will save you $4-$50 on your water bill. This gives you a negative return on investment (ROI), so it certainly doesn't make sense from a cost saving or environmental perspective. But don't take my word for it, there are actual case studies out there with empirical data.

Why Would Anyone Want A Hot Water Recirculation PumpThe reason for installing a hot water circulation pump is pure convenience. If you can't stand waiting a minute for hot water to emerge from the faucet and the operating cost is of no concern to you, then this is the solution for you. For the rest of us there are a few simple things that we can do to gain some convenience and save some money. Insulate: By insulating your hot water pipes you will cut down on the heat lost from the water while it is travelling to your faucet and the water in the pipes will remain hot much longer for the next time you need it. If you already have a recirculation pump, insulating your pipes will significantly reduce the heat loss and will have an immediate ROI. ShowerStart Technology: Showerheads using ShowerStart Technology have a temperature-sensitive switch that turns off the water when the hot water has arrived. While this doesn't stop the cold water in the pipe from going down the drain you can easily collect it in a bucket for watering plants or filling the toilet tank.

Go Tankless: Tankless, or instant water heaters create hot water on demand. Since they are usually located very close to the faucet there is almost not wait for hot water. This solution works well in homes that have very few faucets, or where all the faucets are located in close proximity.

18. Water Heaters: The Hot Spot by Southern California Edison

Water heaters account for about 19% of your home’s energy use and have a lifespan of up to 15 years, so choose wisely when purchasing a new one. If you’re looking to improve the energy efficiency of an existing water heater, there are numerous ways you can lower your energy bills.

Water heaters are the second-largest home energy consumers after heating and cooling units, and can last up to 15 years before needing to be replaced. Take a good look at all the options before choosing the water heater for your living space. If you’re simply looking to upgrade your current water heater, there are several things you can do to improve your water heater’s efficiency.

Most homes in the United States use natural gas to heat their water, with electricity the second – and more costly – choice.  Other options include alternative fuels like propane, heating oil, or solar.

No matter what technology you choose, you should consider purchasing the most efficient option in your budget. Additionally, you can make small lifestyle changes and improvements to your existing heater that can drastically reduce your utility bills.

A water heater’s efficiency is measured by its Energy Factor (EF): the ratio of the water heater’s energy output to the total energy going into the water heater. The higher the EF, the more efficiently the water heater performs.Storage Tank: This is the most common type of water heater in U.S. homes. High-efficiency gas storage tanks differ from regular storage tanks in that they have more insulation, heat traps, enhanced burners, and sometimes power vents to improve gas combustion. The most advanced models have an EF of at least 0.70.Tankless or Demand: Unlike storage tank heaters, tankless heaters don’t maintain a constant supply of hot water, so they take up less space. When you turn on the tap, sensors tell the gas burner to activate and water is heated by running through a heat exchanger. New tankless water heaters have an Energy Factor as high as 0.98. While they are more efficient and ideal for homes with low water use, a study by the National Resource Efficiency Lab found that you can save up to 50% of water heating energy by placing smaller demand heaters at each water outlet: showers, the dishwasher, and clothes washer.Gas Condensing: This type of water heater looks and works like a high efficiency storage tank, but with the added benefit of capturing combustion gases to help heat the water. While more expensive, this technology can save $100 off your annual utility bills1 —even more for larger families.Heat Pump: If you can’t switch to a gas water heater, a heat pump water heater is an efficient electric option. This technology is like a refrigerator, running in reverse. It also acts as a dehumidifier, improving air quality in humid climates or moist basements.

Solar: Solar water heating systems, or solar thermal systems, use the sun’s energy to heat water for your home. These systems include solar collectors, piping, values, storage tanks, and sometimes pumps. A properly installed solar thermal system can save 50-75% of water heating energy2.  Although numerous tax incentives and rebates may decrease the initial and installation costs, solar is still one of the more expensive water heating options, so you’ll need to determine if it is a cost-effective option for your home.

19. Water Heaters: Avoiding Hot Waters? By James Piper

Domestic water heaters found in institutional and commercial facilities provide an often-overlooked opportunity to save energy. Depending on the facility and its demand for domestic hot water, these systems can account for 10-18 percent of total energy use.With the use of new technology and proper maintenance of the installed systems, engineering and maintenance managers can reduce the energy requirements of these systems by up to 50 percent. And while much of the attention of new technology focuses on improved operating efficiency, these systems also can improve safety for operators and building occupants.Condensing Water Heaters

Conventional gas-fired water heaters have a peak operating efficiency of 78-82 percent. They burn fuel in a combustion chamber, and the resulting combustion gasses pass through a heat exchanger, which transfers energy from the gasses to water. Much of the operating loss in these units comes in the form of heat carried out of the unit with the flue gasesWater — a natural byproduct of combustion vapor — carries out part of the energy lost in the flue gases. Condensing water heaters recover much of this energy by using a larger heat exchanger or a second heat exchanger that reduces the flue-gas temperature to the point where this water vapor condenses, releasing even more energy.Condensing water heaters offer a peak operating efficiency of 88-90 percent. Managers typically can recover their extra cost in one to two years’ operation in most facilities and less in facilities with high hot-water demand.Modulating Systems

Conventional water heaters use on/off controls. As the system load varies, the boiler varies the amount of time it is on to meet the demand. Higher demand levels result in longer burn times, and lower demand levels result in longer periods when the burner is off. Only when the boiler operates at peak load does the burner remain on for a long period of time.While on/off controls are simple and inexpensive, they are not very efficient. Water heaters that cycle frequently increase losses through the boiler’s flue gases. Depending on the frequency with which the water heater must cycle, these losses can reduce annual operating efficiency 10-50 percent.Modulating water heaters offer an effective solution for reducing these losses. Instead of simply shutting off the burner when the system meets the demand for hot water, modulating boilers reduce the amount of fuel supplied to the boiler, cutting the rate at which hot water is generated without turning off the burner. Only when demand drastically falls off is the burner actually shut down. Modulating the burner instead of cycling reduces flue-gas losses and increases annual operating efficiencies by up to 50 percent.

New-generation water heaters that modulate the burner while condensing the flue gases can achieve operating efficiencies as high as 92-95 percent.Modular Units

In most commercial and institutional facilities, one water heater is sized to meet the facility’s peak demand. In most facilities though, the demand for hot water varies widely with time of day and day of the week, often by a factor of 10 or more. For conventional water heaters, this means the unit will cycle frequently most of the time. Modulating water heaters reduce the cycling, which still will take place during periods of relatively low demand.An alternative to the single water heater is using multiple, modular units sized to meet a range of hot-water-demand levels. Each modular unit has a much lower capacity that the single, conventional unit. Under low-load conditions, one water heater can provide all of the required hot water. As the load increases, additional units automatically come on line. Depending on the application and the demand for hot water, a facility might have up to 10 modular units.Modular installation — using multiple, smaller water heaters — delivers increased annual operating efficiency over the use of a conventional single unit. The degree of improvement depends on the range of demand for hot water. Managers can expect that for most typical applications, a modular water heater approach can reduce annual energy requirements by at least 10 percent.The use of modular water heaters also means facilities have backup hot-water units available. In a single-water-heater application, one unit failure results in a loss of hot water. But in a modular application, one heater’s failure only reduces system capacity. Hot water is still available.Point-of-use Heaters

In traditional hot-water systems, a central heater generates hot water, which then is distributed through a piping system to all points of use. Larger systems might require circulation pumps and storage tanks.One major drawback of a central system is its overall operating efficiency. Typically, water must run for several seconds for hot water to reach each point of use, wasting both water and the energy used to heat it. Conduction losses from system piping and storage tanks further decreases operating efficiency. Circulation pumps require additional energy. As a result, it is not uncommon to find that the annual operating efficiency of central systems is 50 percent or less.Point-of-use water heaters offer an alternative to the central hot water system. Instead of a single or multiple central water heaters, point-of-use systems feature multiple small water heaters throughout a facility at or near the point where the water is needed.Heaters are sized to meet the demand of that use. They might be instantaneous water heaters or might include a small tank. By eliminating losses associated with central systems, point-of-use water heaters offer vastly improved annual operating efficiencies. Their primary drawback is the additional maintenance required needed to keep the larger number of system components operating and in good condition.Heat-pump Water Heaters

The most efficient water heater is the electric resistance unit, which has an average efficiency greater than 97 percent. While this heater is the most efficient, it also is the most expensive to operate due to the high cost of electricity, compared to other water-heating fuel sources.

New heat-pump water-heater technology offers an electric alternative that has the advantages of very high efficiency and low operating cost. It produces about three times the quantity of hot water for the same amount of electricity.Heat-pump water-heaters operate the same way that HVAC-system heat pumps do. They extract heat from the air and transfer it to the water. New-generation units are small and can readily serve as direct replacements for a range of water heater types and sizes.Maintenance

No matter the type of water heater system installed, maintenance is essential for long-term performance, safety and high operating efficiency. Unfortunately, too many organizations simply ignore most systems until something goes wrong. Water heaters are like any other installed system; maintenance departments must maintain them through a program of regular inspection and testing.Maintenance requirements vary with the size and type of equipment. Technicians should inspect all hot water outlets at least monthly for proper operation and leaks. No matter how efficiently the system provides hot water, waste through leaks and valves that won’t fully close increases both energy and water costs.Technicians also should test and adjust water supply temperature controls at least monthly, and they should inspect the entire system annually for leaks, as well as damage to components and insulation. They should flush all storage tanks annually to remove sediment, and they should inspect larger tanks annually for scale. Finally, to promote safety for mechanics and building occupants, they should test all pressure-relief valves annually. By following these routine maintenance tasks and by upgrading systems, managers can generate significant savings through reduced energy and water use. Spotlight on Safety

New-generation water heaters can reduce the chances of a flashback fire where the water heater is installed. One safety problem related to the use of natural gas- and propane-fueled water heaters is the chance that the heater's flame will ignite flammable vapors in the room.New flammable vapor ignition resistant (FVIR) designs can prevent this type of ignition by trapping and burning gas vapors within the heater, preventing the ignition of flammable vapors present in the space.FVIR water heaters are marketed primarily to the residential market. But since the commercial and institutional market widely uses residential type water heaters, they can help improve safety in these applications, as well. This technology is particularly important when considering the type of materials found stored in spaces near water heaters.

20. Heat Pump Water Heaters: An Energy-Efficient Alternative by Nick Akins

 Heat pumps are most often thought of as heating and cooling systems, but they can also be used to heat water—either as stand-alone water heating systems, or as combination water heating and space conditioning systems. Heat pump water heaters typically have a higher initial purchase price than conventional units, but their lower operating costs can provide a good return on your investment. 

How they workHeat pump water heaters use electricity to move heat from one place to another instead of generating heat directly. Therefore, they can be two to three times more energy efficient than conventional water heaters. To move the heat, heat pumps work like a refrigerator in reverse. While a refrigerator pulls heat from inside the box and into the surrounding room, a heat pump water heater takes heat from the surrounding air and dumps it (at a higher temperature) into a tank to heat water.

You can purchase a stand-alone heat pump water heating system as an integrated unit with built-in water storage tank and backup resistance heating elements, or you can install a system that combines heating, cooling and water heating. These combination systems pull their heat indoors from the outdoor air in the winter and from the indoor air in the summer. Because they remove heat from the air, any type of air-source heat pump system works more efficiently in a warm climate.

Energy efficiency and operating cost

The efficiency of a water heater is measured by energy factor (EF), which indicates the amount of hot water produced compared to the amount of power or fuel consumed. The higher the energy factor the more efficient the water heater. Heat pump water heaters have a much higher energy factor than conventional units; a typical heat pump unit has an EF of 2.0, compared to 0.65 for a high-efficiency gas storage system.It is important to remember that a higher energy factor does not always result in lower operating costs. If you are considering a heat pump water heater, take into account the size of the unit, your water heating needs and energy prices.