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Seattle Plumbing Hot Water Heater Information

HOT WATER HEATER INFORMATION & TYPES OF WATER HEATERS

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Water heaters are typically the largest user of fuel after space heating. The percentage of total fuel used for domestic water heating has been going up over the last ten years because homes tend to be better insulated than they used to. The more you know about your water heating options the better you can make the right decision about the type of water heater you need.


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Tank-type water heaters (gas & electric powered) are the most common here in the Pacific Northwest. They heat water before you need it and store it in the tank. They are available in a wide range of sizes from 6 gallon to 120-gallon storage capacity. The most common size and least expensive, based upon cost per gallon, is a 50-gallon size. A 50-gallon water heater can be installed for the same price as a 40-gallon size for example. A newer water heater will typically be better insulated than an older model. The preferred fuel is natural gas as it is cheaper to operate over time than an electric model. New gas water heaters have more options than the old and they have been re-designed to minimize igniting flammable vapors, which may be present in basements, workshops or garages due to paint fumes or leaking gasoline from a parked car.

Typical installed cost

   

Tankless (instant hot water, continuous or on-demand water heaters) have no storage tank as they heat water only when the faucet or shower is turned on. This type of heater is popular in Europe and is just becoming a popular option here in the USA in the last few years. They come in both gas and electric models however the gas models are much more popular for whole-house water heating. Most are supplied with electronic ignition, doing away with the old standing (running) pilot. Tankless models cost more than storage types and are more complex in their design. Tankless type water heaters must be sized correctly to function as intended. If you go this route we suggest buying the best one you can afford as reliablity is a big factor in lifetime cost. A specialist is recommended for installation. Once installed and sized properly a tankless type water heater can truly supply “endless hot water” continuously. There are multiple choices in this type of water heater.

More tankless information

   

Heat Pump Water Heaters are exotic here in Seattle however they may be worth checking into when gas is not available as they use much less electricity to heat the water than conventional electric resistance elements. This type of water heater removes heat from the surrounding air and puts it into your water. (Think of your refrigerator – it moves the heat out of the fridge to the outside air). One of the potential advantages (or disadvantage) is the fact that it cools and dehumidifies the air in the room the heat pump is located in. This can be a great advantage in the summer or in basement areas that can benefit from dehumidification. (The winter is a different story- I would locate the equipment where outside air can be exchanged). You can save 50% to 65% on your electric bill compared to typical tanks! I think this is a good option when the water heater is in the same room with an old hot water boiler, refrigeration compressors or other incidental heat sources.

   

Indirect water heaters use hot water from a boiler to heat the water in a tank. If you already have a hot water heat system it can provide the hot water you need for your domestic use as well. The hot water from the boiler is circulated through a heat exchanger inside the indirect tank thus heating the domestic water. Indirect tanks last much longer than normal storage type heaters as the heat source is not in or under the tank (that’s why we call them indirect tanks). You get the benefit of your newer boiler’s efficiency that can be as high as 99%! The volume of hot water production is typically much more than a conventional water heater. It can be as much as 200 gallons per hour compared to 40 or 50. If you have a hot water boiler heating your home it is worth looking at the possibility of using it to heat your domestic water with this type of tank. These tanks have long life expectancy.

   

Combination Domestic Hot Water & Space Heating - These machines combine both the domestic hot water for your shower and a space heating hot water maker for heating your house with radiant.

The cost is typically less than two separate hot water making devices and can significantly save space because you do not need both a hot water boiler and a water heater. We like these units when space is at a premium. They typically cost less than installing both a water heater and a boiler. The gas model shown here has a stainless steel tank and a limited lifetime manufacture's warrantee against corrosion.

Fuel efficiency is greater than 90%.

SELECTING A NEW WATER HEATER

Do not underestimate the value of doing your homework when it comes to selecting the right equipment to heat your hot water. Energy costs have gone up and it will pay you to spend a little time before you make the buying decision. Of course, you can pay us to make the decision for you if you desire! You want to find a water heater that gives you what you need and costs you as little as possible over time.

Don’t wait until your water heater is leaking or dead to do your research. Not all equipment is sitting on the floor on any particular day. Some models must be ordered from the factory or a remote distributor taking sometimes as long as a month to get delivered to you. Determine what type of water heater best suits your needs: gas or electric, storage or tankless, stand-alone or add-on to your heating system, etc. Then determine the right size for your family.

How to size your water heater: It is important that your water heater be sized correctly to provide the maximum amount of water used at the busiest time of the day. A storage type tank water heater “1st hour rating” is indicative of your maximum use from a dead start (such as first thing in the AM or after the tank has had time to heat up before you start your tub or shower – typically about an hour). After that quantity of water has been used then the recovery rate is all you get. The tankless or demand type of water heater must be sized according to how many gallons per minute with at least 120 degrees F output temperature. The flow rate is important too. For example: If you want the water heater to keep up with two showers being used at the same time occasionally you must calculate how much water per minute each shower uses (1.8 gallons per minute is typical). Measure the water coming out of your shower or tub spout if you must (get a 5 gallon pail and measure the time it takes to fill it up). In the case of our two shower example being taken as the most water being used then you will need a tankless heater that can deliver at least 3.6 gal./min.

Which fuel? In Seattle use gas if you have it. It is typically the least expensive fuel cost compared to electric or oil. Electric hot water costs 1.47 times natural gas (2008)

Sealed combustion chambers with power venting water heaters are typically much more efficient than atmospheric types (flue pipe goes into the chimney) (they are also safer in some circumstances). Sealed combustion means that outside air is brought in directly to the water heater and exhaust gases are vented directly outside. The combustion chamber is separated from the house air.

Power-vented equipment (but without closed combustion chamber) can use house air for combustion (single pipe flue), but flue gases are vented to the outside with the aid of a fan. In air-tight houses, drawing combustion air from the house and passively venting flue gases up the chimney can sometimes result in back-drafting of dangerous combustion gases into the house.

WATER HEATER EFFICIENCY

The energy efficiency of a storage water heater is indicated by its energy factor (EF), an overall efficiency based on the use of 64 gallons of hot water per day. The first national appliance efficiency standards for water heaters took effect in 1990. New standards, which took effect in January 2004, increased the minimum efficiency levels of water heaters.

The most efficient gas-fired storage type water heaters have energy factors ranging from 0.60 to 0.65, corresponding to estimated gas use below 250 therms/year. Condensing water heaters have energy factors as high as 0.86.

The most efficient electric storage water heaters have energy factors ranging between 0.93 and 0.95, resulting in estimated annual energy use below 4,725 kWh/year. There is little difference between the most efficient electric resistance storage water heaters and the minimum efficiency standard. Fortunately, heat pump water heaters using less than half as much electricity as conventional electric resistance water heaters are becoming commercially available. If you use electricity for water heating, consider installing a heat pump water heater. Otherwise, look for the most efficient electric resistance unit in your size range.

TANKLESS WATER HEATERS

With demand water heaters (i.e. tankless), the manufacturers provide different specifications: the energy input (Btu/hour for gas, kilowatts [kW] for electric); the temperature rise achievable at the rated flow; the flow rate at the listed temperature rise; and so on. In comparing different models, be aware that you aren’t always looking at direct comparisons, especially with temperature rise and flow rate. For example, while one model might list the flow rate at a 100°F temperature rise, another might list the flow rate at 90°. Until there are industry-standard ratings for temperature rise and flow rates, it will be difficult to compare the performance of products from different companies without some math skills and the abilityto get real data from the manufacturer. Some companies are beginning to publish energy factor ratings for these products and this information should make for easier comparisons.

COMPARING THE TRUE COSTS OF WATER HEATERS

When comparing the cost of various water heating options, keep in mind that there are two types of cost you need to look at: purchase cost and operating cost. Life-cycle costs, which take into account both the initial costs and operating costs of different water heaters, provide a much more accurate representation of the true costs of the water heater than the purchase price alone. Life-cycle costs for the most common types of water heaters under typical operating conditions are shown in the table here. When both purchase and operating costs are taken into account, one of the least expensive systems to buy (conventional electric storage) is one of the most costly to operate over a 13-year period. An electric heat pump water heater, though expensive to purchase, has a much lower cost over the long term. A solar water heating system, which costs the most to buy, has the lowest yearly operating cost among electric systems.

UPGRADING YOUR EXISTING WATER HEATER

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: Installing an insulating jacket on your existing water heater is one of the most effective do-it-yourself energy-saving projects, especially if your water heater is in an unheated basement or 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. Some newer water heaters come with fairly high insulation levels, reducing (though not eliminating) the economic advantages of adding additional insulation. In fact, some manufacturers recommend against installing insulating jackets on their energy-efficient models. Always follow directions carefully when installing an insulation jacket. Leave the thermostat(s) accessible. With conventional gas- and oil-fired water heaters, you need to be careful not to restrict the air inlet(s) at the bottom or the draft hood at the top.
  • 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. 

 

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