Tank water heaters better, this green builder says

Over here at the Robinson/Price-Robinson abode, there has been a standoff concerning the new water heater we need so badly. Ours is likely 20 years old and not very efficient. Our gas bill would go down immensely if we replaced that beast.

But the choices are many. Do we get a new and efficient gas-powered tank model? Or a tankless gas-fired model?

Or, if we are planning to install solar power when the prices of photovoltaic systems are expected to drop by 2010, shouldn't we install either an electric-powered tank model or an electric-powered tankless model? (See a comparison of lifecycle costs.)

Trouble is, with the latter two choices, we need about $1,000 worth of electrical work done to give them the 220 volts of power they require.

I'm the one who wants the electric, tankless, on-demand system. And Bill wants the gas-powered tank system. Thus, a standoff.

But I think we might be getting closer to doing it Bill's way, and that's always so much easier all the way around. Spouses, can you relate?

Part of my thinking about the tankless system is that most of the cool green builders I respect are big, big proponents of the tankless systems. And that means a lot to me.

But I was recently contacted by Wes Harding, a green-leaning builder in Long Beach (Lic. No. 895042) who believes that new, super-efficient tank systems are actually the better way to go.

Wes provided a link to an article about a scientific analysis of all systems, but, he noted: "The only problem I see with the article is efficiency is measured in gas or electricity consumed, not the amount of water used."

Here's a chart from the analysis:

In terms of both water and energy savings, Wes is sold on tank water heaters for these reasons:

1. God forbid, but if we are ever in a major earthquake or disaster, where do we get our water supply from if we have converted to tankless? With a tank system, the water in the tank can be used in an emergency.
2. Water is wasted in a tankless system because it has to be heated through a coil before it reaches the point of use.
3. Tankless systems operate on the volume of water. If you set your faucet to a trickle, the heater won't kick in. This allows for "slugs" or cold spurts between the hot-water delivery as well as more water consumed.
4. A limited number of fixtures can be used at one time.
5. More electrical energy is consumed as the amount of water increases because of the energy it takes to provide water pressure.

A few more links from Wes:

• A local company that manufactures on-demand recirculating water pumps. The products stops wasting water and can be added to any water heater.
• A nonprofit that sells energy-efficient products that are very affordable.
• Green companies in Long Beach.

Got questions for Wes? Post them below.

(Photo: Pacific County, Wash.)

Comments

[David Shifflett]

yeah I like the hole idea of the tank myself you never know when you might need that water in an emergency.

[riley]

I have a tankless and will be getting a polypropeline container filled with drinkable water for emergencies.

There are alternatives to using gas and electricity to heat and, perhaps, even recycle water. When I was cruising around Central America we bathed from solar sun showers (marine supply) on the deck of our sailboat. I plan on creating a similar solar system for a backyard shower equipped with biodegradable shampoos and soaps. The grey water can be harvested for my plants. I'm also planning installing a sink that does the same for my outdoor kitchen.

[Matthew Wright]

What about an evacuated tube solar system with a tankless booster.

or an evacuated tube solar system with a close coupled (passive thermosyphon to a roof mounted tank.

then feeding into an air source heat pump tank for winter boosting.

The air source heat pump should be located in a passive solar room so it works at maximum efficiency.

[WiredForStereo]

I think some of your generalizations are just too general.

I have a tankless SEISCO water heater. It's electric, and the only drawback is the wiring cost.

In my case, your #1 is valid. #2, energy usually costs more than water, so keep that in mind there. Besides, my heater only holds a gallon and at least some of it gets heated, so there's likely more wasted in the water line between it and the sink. #3 not true with the SEISCO, true with cheaper electrics and all gassers though. #4 not true, it depends on the rating of the heater and how many low flow fixtures you have. #5 I have no idea what you are talking about. Your water pressure is provided by your water provider, not your water heater. It doesn't matter how much hot water you use, it will always cost more to heat more no matter the heater.

I recommend a solar pre-heater with an electric on demand back-up. Best bang for your buck, and will work well. Just don't use the electric heating element in the solar part.

[Wes Harding]

I want to thank everyone for his or her posted comments and opinions. I would also like to thank Taylor Shaw from Rinnai Corporation, a tankless water heater manufacturer, for the phone call and valid arguments to my opinions on tankless versus tank systems.

I am writing because I want to address Wired For Stereo’s posting. #2 can be fixed with an on demand recirculation water pump. #3 and #4 really depends on the user as well as the brand of tankless and the application whether this is true or false, but in my experience most often times it is true. #5 addresses the amount of energy from the power plant to the water provider that is required to create water pressure and provide water to your doorstep. I am a firm believer in solar and think it is the best option available if you can afford it.