177. Water Heaters 101: Getting yourself in hot water

Smart Homes Series: Part 1 – Choosing the best high efficiency water heater

Category: 2017 Smart Home Series, Energy Efficiency, Net Zero, Renewable Energy, Solar

Tags: , , , , , ,

Published: September 1, 2017

By David Dodge and Scott Rollans

A typical hot water heater accounts for about one fifth of the energy used in most Canadian homes. Choosing the right hot water heater, therefore, can have a huge impact both financially and environmentally—especially as energy prices and carbon levies continue to rise.

Water heater cost to operate

Source: NRCan

Many of us still choose conventional, gas-fired hot water tanks, because they’re cheapest—or, are they? Over its lifespan, the initial price of your hot water heater can represent as little as 12 per cent of its overall cost. The other 88 per cent is energy.

Getting in hot water efficiently

Ken McCullough of Think Mechanical. Photo David Dodge, GreenEnergyFutures.ca

For that 88 per cent, we wanted to get the biggest bang for our buck. So, we asked Ken McCullough of Think Mechanical to walk us through three high-efficiency choices: conventional-style high-efficiency power-vented tank, on-demand tankless, and hybrid heat pump.

“The more people you have in your home, the more hot water you’re going to use,” McCullough observes. “It’s important to know that you have the highest efficiency that you can possibly have. Otherwise, you’re just throwing money out of the window.”

Super-efficient water heater nirvana

EnerGuide says - efficiency matters

EnerGuide sticker for the Rinnai 95% efficient tankless water heater. Photo David Dodge, GreenEnergyFutures.ca

These days, hot water heaters all come with an “energy factor” rating, or EF. A tank with an EF of 1.00 would be perfectly efficient—with all the energy being converted to hot water. This factor is often expressed as a percentage. A standard tank has an efficiency rating of about 60-65 per cent, meaning 35-40  per cent of the energy goes up the flue, or radiates out as the water sits in the tank.

You’ll also want to look at your new system’s recovery rate—the rate at which it can heat the fresh water flowing into the tank. The higher the rate, the less likely you are to run out of hot water during heavy use. Here we present three great choices for dramatically increasing the efficiency of your water heater.

High efficiency power-vented Water Heater

If you’re reluctant around new technology, you might consider a high-efficiency power-vented tank. It looks like an old-school water heater, complete with a 50 gallon tank, but it’s side-vented (like a high-efficiency furnace) to decrease heat loss. This helps boost its efficiency to 90 per cent—or, about 30 per cent more efficient than a traditional tank. Meanwhile, its very high recovery rate, 80 per cent in one hour, will help keep the hot water flowing. You can get a 79 per cent efficient model for $2,700, but the highest efficiency model we looked at clocked in at over $4,800 installed.

Tankless on-demand Water Heater

We were particularly interested in an on-demand tankless hot water heater. As the name suggests, this heater kicks in only when you turn on the hot water tap, heating the water as you use it rather than storing it in a tank. It heats the water quickly enough to provide an endless supply, assuming you’re not using a lot of hot water all at once (say, washing clothes and running the dishwasher while you shower). “You’re going to turn on your tap, and you’ll get hot water,” McCullough says.

With an efficiency ratings of 95-97 per cent, this is the highest efficiency available in a natural-gas water heater. At 95 per cent efficient and priced at $3,700 installed, our choice is more expensive than a conventional water heater, but the long-term savings more than balance that out. And, because there’s no tank, the system frees up a lot of space in your furnace room.

Heat Pump Water Heater

McCullough also showed us the state of the art in efficient water heating: a hybrid heat-pump hot water tank. It looks like a conventional tank, but with a cap on top containing a heat pump. The heat pump draws heat from the air in the (normally very warm) mechanical room—like a refrigerator in reverse—and transfers that heat to the water. This allows the heater to achieve an efficiency rating of 330 per cent, meaning the heat energy transferred to the water is more than triple the amount of electricity consumed.

Because the heat pump water heater is entirely electric, it is perfect for net-zero homes with no gas hookup (meaning you also save $60/month on gas-line administration and delivery charges). Some early adopters are choosing these in conventional homes as well. McCullough quotes $4,400 for this option, making it slightly cheaper than the high-efficiency power-vented tank. The one downside is its relatively slow recovery rate of just 80 liters (21 gallons) per hour.

Summary of three high efficiency choices

Power-vented high efficiency 50-gallon gas water heater

    • • Most similar to conventional
    • • Fast heat recovery rate: 80 per cent in first hour
    • • 90 per cent efficient
    • • Price as quoted: $4,800 installed
    • • Best for those looking for conventional-styled water heater that is more efficient.
Power vented water heater

Tankless, on-demand water heater

    • • 95 per cent efficient
    • • Saves tons of space
    • • Unlimited hot water
    • • Price as quoted: $3,700 installed
    • • Best high-efficiency choice for gas-fired hot water. Favoured by early adopters.
Tankless water heater

Electric 50-gallon Heat Pump Water Heater

  • • 330 per cent efficient
  • • Electric—perfect for solar-powered net-zero home
  • • Slower heat recovery
  • • Price as quoted: $4,400 installed
  • • Best for solar-powered, net-zero homes with no gas line, or those moving in that direction.
Heat pump water heater

A good contractor can help you balance your needs, your budget, and your environmental goals, helping you make the right choice. He or she will also bring pride of work to the installation itself. Shop around and read product reviews—and, remember: spend more up front and save more over the life of the water heater.

We chose the tankless water heater

In the end, we went with a Rinnai tankless water heater in our own home. We consider ourselves early adopters, and we loved the idea of endless supply of hot water. A current, Energy Efficiency Alberta rebate definitely helped put us over the top.

Tankless, endless hot water, 95% efficient

Our new Rinnai tankless water heater is 95% efficient. Photo David Dodge, GreenEnergyFutures.ca

So far, we’re thrilled with our choice—although the quirks of the system created a few start-up challenges. For example, our daughter’s first shower started out hot, but quickly switched to freezing cold. The culprit seemed to be our low-flow shower head; it turns out on-demand heaters require a certain minimum flow rate to remain on. We solved the situation with a single quick adjustment (we turned down the temperature setting from 60 degrees C to 49 degrees C on the water heater, thereby increasing the proportion of hot water needed for a comfortable shower). This has an added benefit of saving more energy—and, we’ve already had two showers going at the same time!

It does take a few seconds longer for the hot water to arrive. But, once it comes, it keeps coming for as long as you need it.

That said, please don’t tell our daughter she can now shower for hours.

177. Hot Water Heaters 101 - Finding the best high efficiency heater

  • Michelle Bynoe

    What about those of us who live meagerly and don’t need a tank? I live in a 1000 sq ft apartment and have decided that I really don’t need a water heater. All I need is hot water to shower with (any more hot water needed can be boiled) so I’m looking for suggestions for shower head heaters.

  • disqus_qUjbrNEMAA

    Uhm, I get less than excited when an system that not only rivals these but exceeds the true capability is overlooked. That system is thermodynamic hot water systems. Cost is higher than the heat pump system, however as a system with low operating costs vs payback, nothing touches it. The tankless system you have requires long-term maintenance, the flame system can fail, the coils also require cleaning, etc. The new tankless systems now incorporate infrared technology that you don’t even mention but it’s clearly available to consumers now in Canada. Thermodynamic systems are the way to go, read more here: http://www.thermodynamics.co.uk/

  • If you want carbon free heating and hot water check out http://www.sunpump.solar

    Think has installed the SunPump in the Edmonton area.

  • Bill Armstrong

    Here’s what I’m looking for. I’m far from gas and the service/rental/maintenance charges for propane plus a high installation cost make this pretty unattractive. This applies to demand propane as well. Demand electric would necessitate a very expensive upgrade to my 100 amp service. My well water is also very cold so I believe I’d need to install something quite over-sized to guarantee satisfactory performance. The hybrid-electric is something I’ve coveted for a long time but very expensive and no local expertise. At 16 kwh per day average total consumption I’m guessing that hot water is 40 to 50% of that total and so potential savings are substantial. I have damp crawl space and basement directly on bedrock so the de-humidification effect of the hybrid is a huge bonus. But it’s noisy and if you read product reviews the long-term reliability problems of hybrid become obvious. Ontario Hydro will subsidize you for upgrading central-air but not for hybrid in a rural home. They say it just scavenges heat from your furnace and so its a zero sum game. That, of course, is hogwash if you heat primarily with wood, where the hybrid allows partial renewable water heating without the complexities of a physical connection between the wood system and water. Nevertheless, my attention has turned to solar. There are at least a few hundred thousand rural homes just like mine. I’m seeing hints of a system that would utilize, say, 3, 250 watt photo-voltaic panels, connected to a controller, connected in turn to the bottom element of a conventional electric water heater. So, very simple solar where the “storage” is your existing water heater tank. Do Canadian certified components for this exist? Seems like a no-brainer to me and possibly less expensive than hybrid and with potentially greater energy savings. If I had any say at Ontario Hydro and if Ontario Hydro was really committed to cutting rural demand (which I doubt) their research lab would be working feverishly on an inexpensive, bullet-proof system like this. Any tips, leads or comments gratefully accepted.

    • Hi Bill, we have seen net-zero homes (with only solar+grid electricity) use electric water heaters. Useually they insulate the heck out of the water heater to help make it more efficient, but increasingly net-zero builders we have seen use hybrid heat pumps. They are pricy, our quote was for $4,400 installed. There are other options as identified in the comments. See this story for a guy who built a net-zero home and then built an insulated box around his standard electric water heater: http://www.greenenergyfutures.ca/episode/net-zero-evolution-star-trek-enterprise-utter-simplicity
      Best advice? Talk to the suppliers of each of your options (talk to folks outside your region if you can’t find the expertise locally) and weigh the cost/benefits carefully. Let us know what you do!

      • Bill Armstrong

        Thank you David. Reading between the lines, I assume that you have not heard about the solar system I described. One problem is that I cab’t shell out more than $2,000. for a device that will pay back at $30. per month. What I really want is something with as few moving parts as possible. I don’t have a heating problem. I gather my own firewood and I’m spending around $200. a year on fuel oil to supplement. (It helps that I’m in Thailand Jan/Feb/March).

        • MacNordic

          Hi Bill,
          while not really in the know about Canadian avaliability of appliances, I can think of three possible solutions for your problem:

          – Hot water stove/ central heating stove
          As you are heating your home with wood, this would be a rather easy addition. Basically, this can be integrated into the water system between the wellpump and the hot water heater, which is used as a hot water tank& can pick up any slogs in hot water provision from the stove. Most installers should be able to integrate that solution, while the cost for the stove is not all that high (at least in Europe – you would get them from about 500€/740CA$)

          – Solar hot water
          Especially in the months from April/May to September (depending on your northern latitude), this could take care of your hot water needs. Flat collectors retail for around 250€ per piece in Europe and a standard household would require around four of them plus a tank. Installation is a bit more complicated, though, as the fluid circulating through the system would need a hot water tank with a coil (heat exchanger), that would need to be added to the system. Heat pipes are generally a bit more efficient (~7%), but more expensive and have more possibilities for problems/ defects.
          A simpler version is the stand- alone Thermosyphon hot water heater, which can be integrated far easier and retail (quick look at Google) for around 1.200US$. The one I found was DIY installation (sunmaxx, but definitely plenty of other options). Even in cold outside temperatures below freezing, they can be pretty effective, even in daylight without direct sunlight hitting them. Good ones have frost protection (self draining) included.

          – Heat pump
          Expensive, but pretty effective. In your case, the best way to draw in the air source would be to place one inlet in your crawl space and another at the highest& warmest point in your house (especially effective under high ceilings, where all the hot air from your fireplace gets trapped). A simple manual switch to change from one inlet to the other would enable the choice between the two sources for instances where you would like to keep the heat under the roof.
          This heat pump could be connected to a PV system via a controll unit, so that it only runs/ mainly runs during the day, when the PV system is producing.
          Unfortunately not cheap, but pretty effective. Don´t know about the possible rebates or subsidies for PV in your area- maybe that could help with financing the complete system.
          Hope this helps a bit!