This is a list of the most important GBA articles on domestic hot water and water heaters.
If you are looking for an index that spans all categories, with a special focus on “how to” articles, check out this resource page: “How to do Everything.”
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Domestic Hot Water
Some questions are easier to answer than others. For example, there is a fairly straightforward answer to, “How should I insulate the floor of my unconditioned attic?” — namely, “With a deep layer of cellulose.” (There’s more to say on the topic, of course — but even a full answer isn’t very complicated.) There is no easy answer, however, to, “How should I heat my domestic hot water?” Every type of water heating technology is flawed; every solution involves compromise. Many factors affect the decision about what type of water heater to choose, including:
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All About Water Heaters
If you want to save energy, there are lots of exciting appliances and building materials that you might want to specify for your home: triple-glazed windows, an efficient refrigerator, and compact fluorescent or LED lighting, for example. When it comes to choosing a water heater, though, clarity evaporates. Simple, affordable water heaters aren’t very efficient, and efficient equipment is complicated and costly. So how do you go about choosing a water heater?
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Are Tankless Water Heaters a Waste of Money?
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.
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Are Tankless Water Heaters Really Green?
Tankless water heaters have one advantage over conventional storage units: no standby losses. Instead of keeping water hot around the clock, regardless of whether it's actually needed, tankless units heat water only when a tap or an appliance is turned on. By rights, this should mean lower energy consumption, a decidedly green advantage.
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Does an Electric Tankless Water Heater Make Sense?
David Voros owns a vacation home that isn't used frequently, but every so often the house sees a lot of guests. What, he asks, is the best way of providing enough hot water for a crowd? Voros sketches out these parameters in a recent Q&A post: very cold incoming water temperatures, a limited amount of space for a tank-style heater, and limited availability of gas. The house has photovoltaic panels, and Voros would like to avoid running another exhaust pipe through the building envelope.
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Point-of-Use Electric Tankless Water Heaters
A couple of years ago, I was standing at my kitchen sink, idly waiting the minute or so for hot water, noticing my poor parched backyard. Central Texas was (and still is) in the death grip of a prolonged, severe drought. Our lakes are in really bad shape, and we are under very tight water restrictions. Then suddenly, I had a mini epiphany: I’m wasting a lot of valuable water while I wait for hot water.
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Storage vs. Tankless Water Heaters
Last week I suggested some ways to reduce your hot water use. This is almost always the easiest way to save energy with water heating—it’s the “low-hanging fruit” to be sure. Over the next few weeks, I’ll get into water heating options. To start, let’s look at the differences between “storage” and “tankless” water heaters.
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The Difference Between Storage and Tankless Water Heaters
There are two primary types of water heaters: storage and tankless. In this column I’ll try to explain the differences between these two approaches and offer some guidance on choosing between them. (There are also “hybrid” water heaters with features of both that I’ll cover in a future blog.) Storage water heaters Most water heaters are storage models. These are insulated tanks holding 20 to 120 gallons with either electric heating elements or gas burners. The storage tank stratifies with hot water at the top and cold incoming water at the bottom, so that as you draw off hot water (from the top), you get consistently hot water until the hot water is nearly depleted. The “first-hour rating” tells you how many gallons of hot water can be delivered in an hour.
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Water Heaters: Tank or Tankless?
Learn how tank and tankless water heaters work, how to choose and size one to suit your needs, and how to save money and energy in the process If you've ever been in the shower and shrieked in dismay when your spouse started up the dishwasher, author Dave Yates has some vital information for you.
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Why Add a Tank to a Tankless Water Heater?
Instant water heaters save energy and offer endless hot water, but not without some problems. A small tank and a big pump can fix the flawsEver been hit by a sudden blast of cold water in the middle of your hot shower, or even just lost hot-water pressure altogether, because someone has decided to do the dishes at the same time you're cleaning up?
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Deciding on a Water Heater
As we build more energy-efficient houses, particularly when we go to extremes with insulation and air tightness, as with Passivhaus projects, water heating becomes a larger and larger share of overall energy consumption. In fact, with some of these ultra-efficient homes, annual energy use for water heating now exceeds that for space heating — even in cold climates. So, it makes increasing sense to focus a lot of attention on water heating. What are the options, and what makes the most sense when we’re trying to create a highly energy-efficient house?
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Get Rid of Your Gas Water Heater!
I was asked to write this blog about naturally aspirated fossil-fuel water heaters in green retrofits as a response to a rather heated debate at the recent National Green Building Conference. The debate occurred in a class co-hosted by Peter Yost and Michael Chandler; in that debate, I stated unequivocally to “get gas water heaters the hell out of the house — they have no place in a green retrofit!”
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Heat-Pump Water Heaters Come of Age
The least expensive way to heat domestic hot water is with natural gas. Homes without access to natural gas usually choose an electric water heater, since electricity is generally cheaper than propane.
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Heat-Pump Water Heaters in Cold Climates
In last week's blog I wrote about the GE GeoSpring heat-pump water heater in our new house — first, why we decided to go with electric water heating over solar thermal (since we use solar to generate as much electricity as we will consume), and then how we decided on a heat-pump water heater instead of one of the other electric water heating options. This week, I’ll get into a little more about heat-pump water heaters and some of the issues that come into play when installing them in cold climates.
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Split-System Heat-Pump Water Heaters
Heat-pump water heaters are a type of air-to-water heat pump. Almost all heat-pump water heaters sold in the U.S. extract heat from the air in the room where the water heater is located, transferring the heat to water in an insulated tank.
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Solar Hot Water
If you’re aiming to reduce your carbon footprint, you’ve probably thought about installing a solar hot water system. Here’s the good news: if you have an unshaded south-facing roof, you can install a solar hot water system that will meet about half your annual hot water needs. The bad news: the typical solar hot water system costs between $6,000 and $10,000.
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Solar Water Heating
Brattleboro, Vermont is fortunate to have a long history with solar water heating. When I moved to the area in 1980, the company Solar Applications had been installing solar hot water systems for five years, and a spin-off company, Solar Alternatives, was manufacturing quality flat-plate solar collectors—many of which are still in use in the area. While Solar Alternatives closed down in the 1980s with falling energy prices and the end of solar tax credits, Solar Applications, has continued to install and service solar water heating systems for more than thirty years.
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Solar Thermal Is Really, Really Dead
Back in early 2012, in an article called “Solar Thermal Is Dead,” I announced that “it’s now cheaper to heat water with a photovoltaic array than solar thermal collectors.” Now that almost three years have passed, it’s worth revisiting the topic. In the years since that article was written, the cost to install a photovoltaic (PV) system has dropped significantly. Moreover, I’ve come across monitoring data that allow for a more accurate estimate of the amount of electricity needed to heat water with electric resistance elements or a heat pump.
