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Q. Dear Umbra,
We are a family of five, with three little boys growing bigger every day. Which is the better environmental investment for our family: to replace our existing hot water heater with a solar model, or to switch to an on-demand, “instantaneous” hot water system?
Thanks!
Gillian and Grant
Toronto, Ont.
A. Dearest Gillian and Grant,
Whaddaya mean, my bath is heated with coal?Solar hot water is the better choice and would still be so if your children grew not one inch taller. Solar hot water takes advantage of the sun hitting your roof, which hopefully happens regularly without costing you money, nor the Earth anguish. A tankless heater will still use a polluting energy source to heat the water. It is a rare ratepayer who gets electricity from all-renewable sources, and Torontoians (?) seem to have the usual mix of coal, gas, nukes, hydro, and so forth.
All a tankless model does differently from your (I assume conventional) hot water heater is heat water as you need it, rather than storing hot water for hours. Like your tank heater, it uses either an electric coil or a gas fire to do this. A tankless on-demand model is, in the best scenario, a bit more efficient than your existing hot water heater. But it still has all the problems of using a non-renewable resource: pollution, greenhouse gas production, a sufficient power generation and delivery system, and of course reliance on the supply of whatever resource is used. You might be interested in reading my earlier column on tankless heaters.
A solar hot water system, on the other hand, can provide the bulk of your hot water needs without using any non-renewable resources (other than those used to make the equipment). Solar hot water is neither a new nor a highly complex technology, so you need not be a brave early adopter to have a system installed. There are a wide variety of systems (again, see a previous Umbra solar water love-fest) to choose from, and there are often financial incentives from one’s city or state. Toronto seems to have a solar hot water initiative heating up right now, in fact, and here is a list of system suppliers to peruse.
The two potential drawbacks that I see are the initial financial outlay and whether your roof and home are well situated. But you won’t know whether these are actual or theoretical drawbacks for your specific situation until you investigate the systems available where you live, their costs, and the fabulous financial incentives that might be coming your way. Here are some resources from the U.S. government on solar water heaters and how to calculate their costs.
Always choose the sun over the coal mine.
Sootily,
Umbra
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Comments
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thollandpe Posted 5:50 am
05 Oct 2009
First order of business should be reducing the load. 1.5 gallon-per-minute (GPM) shower heads and 0.5-GPM aerators in the bathrooms will save significantly. My family likes Bricor and Oxygenics shower heads.
Your solar hot water system will require a backup heater, and tankless is a good option for that.
And another option, a heat pump water heater. Lotza folks run a dehumidifier in the basement and these use an alarming amount of energy. A heat pump water heater can dehumidify while heating your water, a good choice if you have a damp basement and heat water with electricity.
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stinkycheese Posted 9:18 am
05 Oct 2009
With the kids in the house, make sure that your solar contractor installs a mixing valve on the water heater tank outlet; solar can get that tank pretty hot and you don't want 140F (OK, 60C) water coming out of a faucet or showerhead!
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mouseking Posted 7:17 am
12 Oct 2009
Be sure to get a lead-free, mixing valve.
Regards,
Wendell
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Dave Kay Posted 11:58 am
05 Oct 2009
Dave -- greenlifeanswers.com
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timhammond Posted 12:22 pm
05 Oct 2009
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ilayaraja Posted 11:17 pm
05 Oct 2009
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SkyHunter Posted 2:47 pm
05 Oct 2009
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Tasermons Partner Posted 7:22 pm
05 Oct 2009
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neosapiens Posted 8:09 pm
05 Oct 2009
Only an on-demand heater placed very close to the destination can give you instant hot water. Short of that--insulate your pipes! Foam, wrap-around insulation is about a buck for a 6-foot segment. And, be sure that your solar collector and storage system is big enough to meet your needs, otherwise your backup heater will run a lot.
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SkyHunter Posted 8:56 pm
05 Oct 2009
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SkyHunter Posted 8:57 pm
05 Oct 2009
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amazingdrx Posted 7:56 am
06 Oct 2009
So if you get a solar hot water system that only provides enough hot water say 60% of the time, you can always turn on your old water heater when you need it.
Another thing to consider on tankless hot water heaters is that if you were away on vacation and your hot water system springs a leak, your utility meter will spin like a top until you get home. With a regular hot water heater the power consumption would be much lower.
Of course you could just shut off your water and water heater when vacationing too, but not may of us remember to do that.
You may want to check into solar cogeneration, it produces PV electricity from solar cells, using maybe 20% of the solar energy, then a portion of the remaining 80% is captured as heat to provide your hot water. And with solar hot water heating in northern climes where we are (Wisconsin here), heat storage in the form of a phase change salt that transitions at about 105 degrees F is good.
This salt solution stores many times the heat of the equivalent amount of water, and right at the critical temperature needed. I'm not sure if this is commercially available yet. Thestorage salt solution can be "recharged" with offpeak electricty at around half the utility rate too, or waste heat from other sources can help the sun out in providing your hot water supply.
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amazingdrx Posted 8:13 am
06 Oct 2009
A simple manual switch or timer on your present water heater, pays for itself in savings in a few months. Convenience is your only sacrafice, no problem for the environmentally committed.
Tankless heaters involve expensive installation of new gas, vent, or high current electric wiring and they cost 4 times what regular water heaters cost. A catastrophic hot water leak over a weekend when you aren't home can wipe out years of payback savings.
Solar hot water systems have a few years payback in most areas of the US, longer for cloudy areas like Grist's hometown. Combined with a switch on the old water heater, this could be a quick payback. Check into plastic mirrors that track and reflect the sun into your solar hot water heater if you have a roof with poor solar exposure.
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mouseking Posted 7:31 am
12 Oct 2009
Payback is a consideration, but is is really a long-term proposition
when natural gas is available.
Our bill for the gas and delivery to our home via a very reliable pipline system last month was $13.00. It would no doubt be somewhat higher in winter as gas prices are normally higher, and the water ariving at the hot water heater is somewhat colder.
We have 1 GPM restrictors on our basins, 1.5 GPM showerheads, an
energystar/water sense dishwasher, and we haven't used hot water in our
wash machine since 1989 (no rashes or dread, contagious diseases since then). We are awaiting the demise of our electric dryer
(it came with the house) to replace it with a gas-fired dryer; so our off season gas bills are low for that reason too. We are not likely to replace our electric stove/oven with a gas fired one as my wife wants the latest and greatest stove top when that day arrives.
I prefer pilot light gas hot water heaters, as they can be used to keep your home above freezing in all but the most severe climates when power lines are down. One does this by filling bath tubs, sinks and basins with hot water, and refilling them as needed.
With new construction, toilets can be valved to feed in hot water under such circumstances, and each toilet thereby becomes a radiator by turning off one valve and turning on another. Extra flushing is no doubt needed to achieve this end.
Regards,
Wendell
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bailsout Posted 8:17 am
06 Oct 2009
Once I swithched to a tankless heater and realized that everytime I began to turn on the hot water tap I was burning up money/fuel, I started to use cold water for the washing machine(cold water settings still use hot water, so I turned off the hot water valve) and washed dishes by hand in hot water from a solar bag(18.99) which I put in an ice chest 'til I need it and rinse in cold. In the winter I heat water on my woodburning stove and store it the same way. I also take solar heated showers from the coils of black irrigation hose.The water heater paid for itself the first year.
Tank water heaters should be illegal.
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8tona Posted 1:40 pm
06 Oct 2009
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BadRabbit Posted 5:07 pm
06 Oct 2009
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dexter Posted 7:38 am
09 Oct 2009
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Dave Kay Posted 8:29 am
09 Oct 2009
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mouseking Posted 8:53 am
12 Oct 2009
Payback is a consideration, but is is really a long-term proposition
when natural gas is available.
Our bill for the gas and delivery to our home via a very reliable pipline system last month was $13.00. It would no doubt be somewhat higher in winter as gas prices are normally higher, and the water ariving at the water heater is somewhat colder.
We have 1 GPM restrictors on our basins, 1.5 GPM showerheads, an
energystar/water sense dishwasher, and we haven't used hot water in our
wash machine since 1989 (no rashes or dread, contagious diseases since then). We are awaiting the demise of our electric dryer
(it came with the house) to replace it with a gas-fired dryer; so our off season gas bills are low for that reason too. We are not likely to replace our electric stove/oven with a gas fired one as my wife wants the latest and greatest stove top when that day arrives.
I prefer pilot light gas water heaters, as they can be used to keep your home above freezing in all but the most severe climates when power lines are down or while waiting for the furnace repair tech. One does this by filling bath tubs, sinks and basins with hot water, and refilling them as needed. Electric heaters are also an option in the latter case.
With new construction, toilets can be valved to feed in hot water under no-electricity circumstances, and each toilet thereby becomes a radiator by turning off one valve and turning on another. Extra flushing is no doubt needed to achieve this end. Without the hot-water option, remember that the water delivered to your home is likely to be 50 to 55 degrees F; so, frozen pipes and toilets can be avoided by running and flushing respectively. The house is likely to pick up a few BTUs in the process as well.
All bets are off when you are away during such emergencies. An automated generator should do the trick --now we are talking big bucks.
If not, a call to one's answering machine on days/nights when outside temperatures are likely to be in the freezing range (http://www.weather.com) will give you some peace of mind, as, if there is no answer, you know the worst has happened. The next call is to the cell phone of your trusted keeper of the keys to take emergency measures in your absence.
There are devices available to warn you of low house temperatures
when the electricity is O.K. --by calling your cell phone, as an example.
We happen to get by automatically under those circumstances by having some permanently installed electric heaters that we keep set on 45 degrees F and keeping the doors open under sinks and basins to avoid freezing pipes while away. This has served us well in northern New Jersey since 1997. You have to evaluate the risk for your own climate zone.
Regards,
Wendell
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