Save with the right heater, the right habits
Hot water heaters sure look different outside North America. North Americans heat huge tanks of water, and keep them hot all the time, so that we can have as much hot water as we want, whenever we want it (until two loads of laundry, or a deep-soak bath, uses it all up).
In Europe and Asia (at least where I’ve visited or lived), water heaters are much smaller and can be far more efficient. Those energy-conscious countries figured out long ago that it’s a big waste to heat water you’re not about to use – because that heat eventually escapes, and so you keep having to reheat the same water.
In this Hot water heaters section of Green Energy Efficient Homes, I have pages on:
Electric hot water tanks, which typically cost a bundle to operate because heating with electricity is usually much more expensive than heating with natural gas. But there are ways to save with an electric hot water tank – I provide seven tips that make a big difference in your electric hot water bill.
Electric tankless water heaters, and gas on demand water heaters, also referred to as ‘forever hot water’ or ‘tankless water heaters’, can be 30% or 40% more efficient than the standard North American tank heater. But every solution has its own set of problems, and if you’re thinking of switching to an electric on demand heater, at least (as opposed to a gas on demand heater), you might be buying into something that’s already started to go out of style. These heaters can create challenges for utilities trying to anticipate minute-by- minute electrical demand, and I’ve heard that some countries where these heaters are very common, are encouraging people to go in the opposite direction – energy efficient storage electric water heaters – to make electrical demand management easier for utilities.
Point of use water heaters can be useful where you need a small amount of hot water at a time (for instance a kitchen or bathroom sink), and there’s a lot of hot water pipe between the sink and your main hot water source. But while these units offer convenience and fast hot water, they don’t necessarily save you energy.
Electric shower head heaters, which heat water right as it comes out of the shower, are popular in Asia, Latin America, and Europe, and are starting to be sold in North America. They are good for RV’s, for example, where a hot water tank can be too bulky. They’re great if you only need hot water for showers – which is often true in hot countries, such as Costa Rica where I’ve been living for the last 10 months, and have found these electric shower heads to work quite well.
Another angle on cutting energy expenses at the showerhead is the shower head valve, a nifty device that lets the water run out your shower head until it reaches a comfortable temperature, and then drops the flow to a trickle. Once you’re ready to hop in the shower you pull a cord and the flow of hot water starts up again, so you save all that water you would otherwise waste while you get distracted with other bathroom tasks in the morning.
Finally, below on this page I offer some insights below on why on demand water heaters and electric shower heads haven’t really caught on, some advantages of gas water heaters, and some easy tips on saving hot water. Don’t forget to check out my Energy saving washer page, in my Energy saving household section, for tips on saving hot water when doing laundry.
Why isn’t on-demand in demand?
So why aren’t we lining up to buy on demand water heaters or electric shower heads?
For tankless heaters, the catch is, a switch means there are some habits you’ll have to change. And some of the tankless water heaters being sold in North America now aren’t easy to get used to. At my sister’s house, the cleaning woman broke the on demand water heater because she turned the water on and off a few times in a short time period – something most of us wouldn’t think anything of. A few hundred dollars worth of repairs later, my sister is ready to switch back in spite of the extra energy cost!
Solar water heaters are definitely gaining a foothold in sunny, warm climates, but can be costly to buy and install professionally. But you can easily build your own solar hot water preheater – it warms the water going in to your tank so you use less natural gas or electricity to heat it. This is solar hot water without the headache of cold showers on cloudy days. Great for the do-it-yourself person.
As for the electric shower head heaters, they work great – as long as you don’t get electrocuted or burned!
Natural gas hot water heaters – are they better than electric?
Natural gas hot water heaters have several advantages over electric heaters. Foremost is that they usually cost less to operate, because most of the energy in the fuel source (natural gas) produces heat in your gas hot water heater, whereas for electricity, if the original energy used to generate the electricity is a fossil fuel, about two thirds of the heat from burning the fossil fuel is lost to generation inefficiencies.
For more on the relative merits of natural gas versus other heat sources for hot water, see Natural gas advantages and disadvantages.
Some simple hot water tips
Other than replacing old tank water heaters with more energy efficient on demand ones, or building your own solar hot water heater, here are some ideas to try out:
Turn it down when you head out of town. Most tank hot water heaters have a temperature dial with a spot marked ‘Vacation’ (closer to the ‘Warm’ end of the dial). Turn the dial to there 12 to 24 hours before you head out on vacation – there’s usually enough heat left in the tank for one last shower or load of dishes before you go. (And the longer you can wait before turning it back up when you get back from vacation, the better!)
Turn it down when you’re in town. Most hot water heaters are turned up too high. If you can’t hold your hand under the tap without burning, when the hot water is running on its own, turn the temperature lower. It’s safer and you’ll save.
Insulate. Install an insulating blanket around your hot water heater if it’s safe to do so. This is generally safe for electric hot water heaters. Local fire or building codes may prohibit or recommend against it for gas water heaters. Consult those codes and use your judgment. And certainly install insulated pipe wrappers, such as Armaflex insulation, around the pipes coming out of your hot water heater – as far as you can go. The hot water that got stuck there the last time someone turned off the hot water will stay warm longer. If the next use is just to wash your hands or do some dishes, that extra heat can be put to good use instead of being wasted.
Bathe less. Shower more. Baths use a lot more hot water than a quick shower, especially once you’ve switched your shower to a low-flow showerhead.
Bathe less. Shower less. North Americans bathe (or shower) too often. Not only is it wasteful, it’s unhealthy too! Chlorinated water doesn’t cause much harm when you swallow it – but when you breathe the chlorine from hot shower steam, it can really get to your lungs. And your skin didn’t evolve getting scrubbed down with soak seven times a week. Learn to get by on fewer showers.
Use a low-flow shower head. Choose a shower head that limits the amount of water that comes out. Traditional shower heads use up to 5 gallons per minute of hot water; low-flow shower heads use about half that much.
I’ve also got tips on kitchen washing and on laundry in the Energy saving household section of my site, which can help you cut your hot water use further.
I don’t own a home yet, but the concept of the on-demand water heater sounds interesting. I have a few questions:
1. How long does it typically take for the system to heat up the water before one has access to the hot water?
2. Do you currently have this system in your home and if so, have you found that it has actually saved on energy costs? I was told that the system does not save people as much money as the advertising states. But since I am not 100% certain how the system works, I thought I would ask you about it.
3. Do you know much about the Indian water-heating system? What do you think of it in terms of energy efficiency? As you probably know, a geyser is also an on-demand system.
To answer Paula’s questions:
1) The heat usually comes on within a few seconds of turning a tap on (as long as you turn it on enough – if you turn it on just a little, there’s not enough flow to activate the heater, and the water will come out cold indefinitely). It may then take anywhere from 5 to 30 seconds to reach your tap depending on whether you have 1/2″ or 3/4″ pipes and how far the tap is from the heater.
2) I don’t have one of these in my current home. I have lived in a house with a gas on demand heater (but wasn’t paying the bills) and an electric on demand heater. Usually people advertise the savings under ideal conditions, so it’s true you will probably not save as much as advertised. Also, anyone coming to this site may already be conscious about conserving energy. If you’re using half as much hot water as a typical North American family, and you switch to a more efficient water heater, expect to see half as much savings as are advertised. Finally bear in mind the Jevons paradox, which states that every increase in efficiency is met with an inverse increase in usage. Once you know the heater is more efficient you might be tempted to take longer showers or deeper baths, for instance.
3) I have not heard about Indian water heating systems. Would love to know more.
For the past couple of weeks, while bathing my 2-year-old son, the water seems to be getting colder. I was compelled by the article to know that tankless water heaters can be 30% or 40% more efficient than the standard North American tank heater. I will be sure to get an expert’s opinion about my hot water unit!
A great way of improving efficiency of hot showers is with a drain water heat recovery system (DWHR). We heat water to shower with and use it for a few seconds, then most of the heat goes down the drain. A DWHR system uses that heat to preheat your water before going to the hot water tank, therefore reducing the energy needed to heat it to the desired temperature. They are simple to install and have no moving parts. I bought a Power-Pipe brand unit about 5 years ago and installed it myself in a couple of hours. A real plumber could do it way faster. Efficiency depends on the diameter and length of your unit. Mine is 48% efficient at recovering the waste heat; some are a fair bit better.