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Hot Water
Hot Water Conservation Checklist
• Can you reduce your hot water temperature?
• Do your showers have low-flow showerheads?
• Do you fix water leaks promptly?
• Do you wash clothes in cold water?
How Much Do I Spend Heating Water?
Heating your water can be expensive. A typical four-person household spends between
$500 and $800 a year on hot water. It can cost hundreds of dollars more if you waste it or
heat it inefficiently. Poor water-use habits can more than double the amount of hot water
each person uses. Wherever you use water there is potential for savings.
Where Does All That Hot Water Go?
A typical Canadian uses 230 litres (50 gallons) of water in the home each day for washing dishes and clothes, personal hygiene, household cleaning, and food preparation. Almost a third of that amount – 68 litres (15 gallons) – is hot water.
Using less hot water will benefit both your pocketbook and the environment, because using less energy means less pollution. Reduced water use may also help to alleviate seasonal water supply shortages.
How Can I Reduce My Hot Water Costs?
You can save both energy and water with inexpensive changes like installing low-flow showerheads and aerators, reducing the temperature of your hot water, or insulating the water heater or water pipes. It may also be possible to improve the efficiency of your water heater.
Steps To Reduce Water Heating Costs
REDUCE HOT WATER TEMPERATURES
The hotter the water, the more it costs to heat. A water temperature of 52° C (125° F) is hot enough for household use. If this isn’t adequate, raise the temperature by 2.5° (5° F) at a time until you are satisfied. Lower-temperature water also cuts the risk of scalds—an important safety concern with small children.
Reducing the water temperature from 60° C (140° F) to 52° C (125° F) can cut heating costs by 12–15 per cent. Be sure to reset new water heaters, since the factory setting is usually 60° C (140° F).
Important Note: DO NOT lower the temperature
of your hot water below 60° C (140° F) if anyone in your home has health conditions such as chronic obstructive pulmonary disease or a weakened immune system or is taking immunosuppressive drugs that might raise the risk of legionnaires’ disease. Talk to your doctor for specific advice.
INSTALL LOW-FLOW SHOWERHEADS
If you use the shower, buy a low-flow showerhead. It can pay for itself in water and energy savings in as little as two months. Typical savings could range from 10 to 20 cents per five-minute shower, depending on the water use of the old showerhead, household water pressure, and the type of water heater used in the home.
Quality low-flow heads can be purchased for under $10 (try your local water utility). More-elabo-rate hand-held low-flow showerheads may cost $25 or more.
Low-flow showerheads use 7–10 litres
(1.5–2.2 gallons) of water per minute. Many older or low-quality showerheads gush more than twice as much water and still do not provide a quality shower. Low-flow showerheads come in a multitude of shapes, sizes, and spray patterns.
To test the flow rate of your showerhead, place a 4.5-litre (1-gallon) container under it. If the container overflows in less than 25 seconds, replace your showerhead. Reducing water flows by 25 to 50 per cent can also help solve hot water shortages in your home caused by heavy shower use.
FIX LEAKS
A hot water leak of one drop per second will waste 700 litres (155 gallons) of water a month. With an electric water heater this leak will cost about $60 in electricity and $9 in water (Halifax area rates) each year. A leaking shower diverter valve can waste even more hot water. Don’t put it off—fix leaks now and save.
REDUCE PIPE HEAT LOSSES
All hot water piping in unheated basements or crawl spaces should be insulated. In a heated basement, insulate at least the first 3 metres (10 feet) of the hot and cold water pipes leaving the water heater. Glass fibre or foam snap-on pipe insulation installs easily and works well. Wrap-on insulation tends to be harder to apply neatly and usually has lower insulation values.
A heat trap is a U-shaped section of pipe that provides a well or “trap” for cooler, heavier water to collect in. The heat trap reduces the amount of heat escaping up the distribution piping when hot water isn’t being used.
Inefficient showerhead. Efficient showerhead. Heat Traps Hot Water Storage Tank Shut-off Valve Hot Cold Heat
Trap Heat Trap
REDUCE WASHING MACHINE HOT WATER USE
Washing clothes in warm or cold water will save you money. You can cut hot water use by about two-thirds by choosing a warm water wash and cold water rinse. Better still, a cold water wash doesn’t use any hot water and is easier on clothing too.
Modern front-loading washers use up to half the water used in conventional top-loading models. Clothes washed in front-loading washers remove more water during the spin cycle, so shorter drying times can cut your energy use even more. Look for the Energy Star rating when purchasing new equipment.
RUN FULL DISHWASHER LOADS
All of the water used in a dishwasher is hot, so try to run full loads. Many dishwashers don’t require pre-rinsing. Newer models can use substantially less water than older models.
Air drying dishes is more energy efficient than using the dishwasher heater. Just select the no heat option or open the door at the start of the drying cycle.
REDUCE SINK WATER USE
Low-flow faucet aerators can reduce water flow by up to 50 per cent. Use mid-efficiency units, 6–9 litres per minute (1.3–2 gallons per minute), in the kitchen and high-efficiency models (1.8 litres/0.4 gallons per minute) in the bathroom.
You can save 9–23 litres (2–5 gallons) of water each time you shave by partially filling the basin, instead of letting the water run continuously. Use short bursts of water for rinsing when brushing your teeth.
MAINTAIN YOUR WATER HEATER
Drain water from the water heater at least once a year to remove sediment build-up. If your water quality is poor, more frequent draining may be needed.
Oil and gas water heaters should be cleaned and tuned annually. Tuning should include an efficiency test.
DRAIN WATER HEAT RECOVERY
Drain water heat recovery devices replace a section of vertical drain pipe in the home’s sewer system. Heat in the waste water flowing down the inside of the pipe transfers through the copper drain pipe. This preheats water in a coil of copper tubing tightly wrapped around the outside of the heat recovery device’s drain pipe. This preheated water reduces household energy use by reducing the amount of heat that must be added by the water heater.
Drain Water Heat Recovery Device
Incoming cold water Fresh water supply connected to inlet Connect outgoing warm water to water heater and/or cold water supply
of home
INSULATE YOUR ELECTRIC WATER HEATER
An insulation blanket on an older electric water heater typically saves enough energy to pay for itself within a year. These blankets are easy to install and are sold at some home improvement stores. Don’t cover the drain faucet or the pressure relief valve. For new installations on uninsulated concrete floors, place rigid foam insulation between the water tank and the floor to reduce heat loss.
SHUT OFF YOUR WATER HEATER WHEN YOU ARE AWAY
Water heaters, particularly oil- or gas-fired water heat-ers with a central flue pipe, can waste a substantial amount of energy keeping water warm when there isn’t any demand. Save energy by turning your water heater off when you are away from your home for extended periods.
Can I Reduce My Cold Water Use Too?
Conventional toilets waste water. Inspect tanks to ensure that the float is set properly and the flush flapper seals tightly. If water flows down the overflow tube, or the flapper leaks water into the bowl, make repairs immediately. Flapper leaks can be detected by putting vegetable dye into the tank water. If the dye appears in the bowl before the toilet is flushed, your flapper leaks.
You may be able to reduce the water use of your existing toilet by installing a toilet dam or placing a weighted plastic bottle in the tank. Bricks are not recommended, since grit from the brick may damage the toilet’s mechanisms.
Low-flush toilets (6 litres or less) are now widely available at a reasonable cost. Legislation in some jurisdictions such as the United States actually prohibits the sale of units that use more than 6 litres per flush. Dual-flush toilets and waterless urinals are also available. Water-efficient appliances can extend the life and reduce the pressure on a marginal well or septic system.
TYPICAL HOUSEHOLD WATER USE
Toilet 45%
Showers/bathing 30% Food preparation and cleanup 5% General household use 20%
Should I Replace My Existing Water Heater?
Water heaters are usually replaced when they leak or if they can’t supply enough hot water. If your water heater needs to be replaced, switching from one type to another may produce modest dollar savings. Reducing hot water use generally saves more, at much lower cost, than switching from one type of water heater to another.
What Type of Water Heater Should I Buy?
Consider the following factors when choosing a water heater:
• How do you heat your home? If you have hot water
heating, the same boiler you use for heat can probably also supply domestic hot water.
• How much hot water do you use? Households
that use lots of hot water should select a system with low operating costs and the capacity to
produce lots of hot water, even if the initial cost is higher. If your household doesn’t use much hot water, an electric water heater may be the least expensive option.
• What are your peak hot water requirements? You
will need a high-capacity system if your home has high-volume demands, such as a large hot tub.
• How much space is available? Water heaters
with venting requirements need more space and must be located near a chimney or an outside wall suitable for side venting. An advantage of an unvented (electric) water heater is that it may be possible to shorten supply pipes by installing it near the kitchen or bathrooms.
• Which fuels are already on site? Piggybacking
onto an existing fuel supply costs less than installing a new fuel tank or upgrading a marginal electrical service.
Water Heater Comparison Chart
Installed Operating Capacity/ Maintenance Average
Type Cost Costs (2007) Recovery rate Requirements Lifespan Other Electric
• 180 L (40 gal.) Low High Medium – Low Medium Flexible • 270 L (60 gal.) Low High Medium + Low Medium Placement
Oil Stand-Alone High High + High High Short Must Be Vented
Propane Stand-Alone
• standard Medium Very High High Medium Medium Must Be Vented • high efficiency High High High Medium Medium Must Be Vented
Natural Gas Stand-Alone
• standard Medium Medium + High Medium Medium Must Be Vented • high efficiency High Medium High Medium Medium Must Be Vented
Tankless Coil Low High High Low Medium Needs Boiler
Indirect High Medium High Low Long Needs Boiler
DOES YOUR HOME HAVE A BOILER?
An indirect water-heating tank usually costs less to own and operate than a separate water heater, when all ownership costs are considered.
• Indirect-fired water heaters store hot tap water in
an insulated tank (usually 90–225 litres/20–50 gallons). This water is heated with hot boiler water via a heat exchanger. Hot water temperature can be accurately set, and large water uses can be accommodated.
An indirect water heater costs more to install than a tankless coil, but less to operate, especially if combined with a small cast-iron boiler that operates only when heat is actually needed. Conventional steel boilers are less efficient, since they must cycle on and off to maintain boiler temperatures even when no hot water is being used.
• A tankless coil in a heating boiler is, as its name
suggests, a coil of tubing containing potable water that is immersed in the boiler’s hot water reservoir. Properly sized tankless coils can supply hot water continuously.
Tankless coils can’t store water, so the boiler’s water reservoir must always be hot for the coil to function. The burner’s capacity may need to be over-sized relative to the home’s heating requirements for the coil to keep up with high hot water demands. Tankless coils are inefficient during warmer months, since the boiler must be kept hot continuously even though space heating isn’t required.
Because boiler temperatures must be high to heat your home properly, the temperature of water leaving a tankless coil can be too hot for safe household use. For both safety and economy, tankless coil heaters need a mixing valve to add enough cold water to reduce hot water to a safe temperature.
WHAT IF I NEED A STAND-ALONE WATER HEATER?
• Electric water heaters can be purchased for under
$300 and can be installed almost anywhere. When energy and purchase costs are factored in, electric water heaters are usually the least expensive type of water heater in households that don’t use much hot water.
The recovery rate of electric water heaters is slower than of oil or gas water heaters, but proper sizing can minimize this concern.
• Oil-fired water heaters are usually rented from
fuel-oil suppliers for $120 to $160 per year, since purchasing a 135-litre (30-gallon) oil-fired water heater costs over $1,000. Oil-fired water heaters have a high recovery rate
The overall seasonal efficiency of conventional oil-fired water heaters is low, due to inefficient heat exchangers and high standby losses from heat escaping up the chimney when the water heater isn’t running.
• Gas water heaters are common in regions served
by natural gas. High-efficiency gas water heaters can have exhaust gas temperatures low enough to be vented through a small-diameter plastic pipe. Less-efficient gas water heaters, similar to oil-fired water heaters, are also available. High-efficiency water heaters offer better long-term value—even if they cost more initially.
At 2007 residential propane prices, heating hot water with propane is expensive. Plus, you must also rent a propane fuel storage tank if you don’t have any other propane appliances.
• Solar water heaters are an environmentally
respon-sible way to heat hot water. For best economy, they are usually sized to meet about 60 per cent of total hot water needs and are operated in series with another water heater. On hot days, solar water heaters can supply all your household hot water needs. In the colder months, they preheat water before it enters your conventional water heater. Solar water heaters cost very little to operate,
but have an initial installed of $4,000 to $6,000. Users with high daytime hot water needs are the best match for a solar water heater. Solar rebates are available from the federal and provincial governments. Call Conserve Nova Scotia’s ENERinfo line at 1-800-670-4636 (toll-free) to find out more about solar rebates.
Thermostatic mixing valve installation.
HOW CAN I SAVE ON HOT WATER COSTS WITH MY HOT TUB OR POOL?
• Spas and large hot tubs need insulated covers to
reduce heat loss during periods when they are not in use. Insulation around the tub limits heat loss between uses. A high-capacity water heater will be required for acceptable performance.
• Outdoor swimming pools should have an insulated
pool blanket to conserve heat and pool chemicals when the pool is not in use. An uncovered pool can lose as much as 5 centimetres (2 inches) of water a week to evaporation. Above-ground pools used during the spring or fall should be insulated on the perimeter to reduce heat loss.
Low-cost solar pool heaters work very well during the warmer months when outdoor pools are in use. They cut energy costs and can also extend the pool’s useful season by several weeks.
How Do I Lower Water Heater
Temperatures?
ELECTRIC WATER HEATERS
First, turn off the power to the water heater by either (1) moving the disconnect switch at the heater to the off position or (2) opening the circuit breaker or removing both fuses at the electrical panel. Standard heaters have an upper and lower thermostat behind access plates on the front of the heater. Set both thermostats to the same temperature by turning the dial with a screwdriver.
OIL, PROPANE, OR INDIRECT WATER HEATERS
Thermostats are usually located in a small box on the front of the unit. Usually, the temperature setting can be adjusted with a screwdriver without opening the box. Turn off the power if the box cover must be removed to adjust the temperature setting.
The ENERinfo Advisor Series
Brochures available in this series include: • Building an Energy-Efficient Home • Selecting Energy-Efficient Windows • Introduction to Home Heating • Passive Solar Homes
• Ventilation for Older Homes • Ventilation for New Homes
Other Information Sources
Canada Mortgage and Housing Corporation www.cmhc-schl.gc.ca
Office of Energy Efficiency
Rev. 01/08
Ask ENERinfo
Please address requests for more information or publications to:
ENERINFO at 1-800-670-4636 (toll-free) www.conservens.ca
or write: Conserve Nova Scotia PO Box 153, Halifax, NS B3J 2M4
