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Solar at Home


The trials, tribulations and rewards of going solar
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How to become more energy-efficient once you’ve picked the low-hanging fruit

The views expressed are those of the author and are not necessarily those of Scientific American.


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Editor’s Note: Scientific American‘s George Musser will be chronicling his experiences installing solar panels in 60-Second Solar. Read his introduction here and see all posts here.

solar panels, solar installation, water heaterAs we continue to wait for our solar paperwork to go through to receive the subsidies and loans, I’ve kept looking for ways to save energy, and I’ve come to a sad realization. It looks like we’ve already done most of the no-brainers. We’ve weatherstripped doors, sealed air leaks, blown in insulation, tweaked our steam heat system, screwed in compact fluorescents and LEDs, and turned our five-year-old daughter into a zealot for turning off lights. Gone are the days when I came home from work only to find every single light in the house turned on.

But the fruit is getting steadily harder to pick, and the household finances are now working against the cause of energy conservation. Our water heater is a good example. We currently have a gas-fired storage water heater. It’s about 15 years old and last week the drain valve sprang a small leak, so I figured this would be the time to replace it with one of the tankless units that conservation advocates wax eloquent about. A tankless unit heats the water only when we actually need it, unlike the storage unit, which maintains a reservoir of hot water (50 gallons, in our case) that has to be continually reheated as heat escapes into the basement and up the chimney. Our family needs hot water only in the mornings and evenings, yet our water heater runs 24/7.

The energy factor—a measure of efficiency—of tankless units is typically 0.85, compared to 0.62 for storage heaters. To sweeten the deal, the state of New Jersey offers $300 rebates for tankless units and the Feds now offer a $1,500 tax credit on this and other energy-saving measures.

So it seems like a open-and-shut case. Yet our plumber tells that half his customers who get tankless water heaters later ask to have them removed. One big disadvantage is that such heaters have not only a maximum flow rate, but also a minimum flow rate. If you just turn on the faucet for a small amount of hot water, the unit won’t fire. When I told this to my wife, I could see my dreams of a tankless unit swish down the drain.

I thought I could talk her around, until I considered the cost. Replacing our storage unit will run about $1,400, whereas a tankless unit would cost twice as much. Even with the rebate, the payback time is measured in decades. About the only financial justification for tankless heaters seems to be the fact they last longer, but that’s too long-term a proposition for me. Consumer Reports reached a similar conclusion last fall.

Never one to be daunted, I began to look for other ways to reduce my water-heating bill, only to be stymied at every turn. A so-called indirect water heater, which would use our main steam-heat system to heat the water, is said to be extremely efficient. But I couldn’t find any data to support this claim, and I stopped looking when I found out that the system is twice as expensive as the tankless unit.

I thought about getting an ultra-high-efficiency storage heater, but began to cough uncontrollably when I saw the price—even higher than the indirect unit. And I looked for a timer for my cheapo storage heater, so that we could shut it off during off-peak hours, yet such timers bizarrely don’t seem to be exist for gas water heaters (even ones with electronic ignition).

About the only useful contraption I could find was a coil that wraps around the water drain to extract some of the waste heat and return it to the water heater. I’ll probably install it, if only to salvage some pride from this whole episode. If anyone has other ideas, I’ll all ears.

I’ve also hit a brick wall on how to save money on space heating. Replacing our boiler with a smaller one would eventually save money, but again it would take a decade to pay off the $5,000+ cost. Retrofitting our steam heat with hot water or air is similarly cost-ineffective. The contractors I talked to said they wouldn’t even give me an estimate for a full retrofit, because they knew I would choke on it.

And so my family finds itself in the same predicament as many around the country. We want to do the right thing, but it just costs too much. I’m just not sure policymakers who want owners of older homes to cut costs are going to get them to do that unless they provide the subsidies that they now provide to solar.

Photo of George’s current water heater





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  1. 1. jellyfish 9:00 am 04/29/2009

    I find this surprising. I have a tankless hot water heater (Baxi brand) and it doesn’t appear to have any minimum flow requirement. It provides hot water nearly instantly, any time of day, no matter how much or how little we need. I can fill up a small cup or take a 30-minute shower, and both are piping hot.

    Link to this
  2. 2. zacks 11:02 am 04/29/2009

    Suggestions for further savings on hot water costs: 1. Reduce hot water usage; shorter showers, ‘Navy’ shower (wet, turn off water, soap, rinse- we use with RV and is water AND energy saving), 2. Insulating blanket on water heater (low cost, better and cheaper than heat reclaiming). 3. Turn down water temperature on water heater. 4. Turn off hot water recirculating pump (if you have one) or put the pump on a timer. If you have a recirc pump, also insulate the pipes that carry recirc water where access is possible (crawlspaces, etc.)

    Link to this
  3. 3. zacks 11:03 am 04/29/2009

    Suggestions for further savings on hot water costs: 1. Reduce hot water usage; shorter showers, ‘Navy’ shower (wet, turn off water, soap, rinse- we use with RV and is water AND energy saving), 2. Insulating blanket on water heater (low cost, better and cheaper than heat reclaiming). 3. Turn down water temperature on water heater. 4. Turn off hot water recirculating pump (if you have one) or put the pump on a timer. If you have a recirc pump, also insulate the pipes that carry recirc water where access is possible (crawlspaces, etc.)

    Link to this
  4. 4. nbolds442 2:18 pm 04/29/2009

    The units I have worked with use a magnet to activate a reed switch. The magnet is pushed up by water flow so If you are running a tiny amount of hot water the magnet will not activate the heater because there is not enough pressure to get it to rise. I am surprised though that no one makes a timer for the hot water thermostat like you have with forced air furnaces for homes. It might just not be economical to turn it down for a couple of hours a day.

    Link to this
  5. 5. Whatever 3:25 pm 04/29/2009

    This still amazes me: why on earth should money be the only measure? Couldn’t you choose to have something more expensive, but more environment friendly? When whole countries (indeed, continents) are thinking like this –money (i.e. economy) first– you don’t need to look further for the failures of "green politics".

    Link to this
  6. 6. Biodiversivist 5:11 pm 04/29/2009

    Consider moveable night insulation:

    http://biodiversivist.blogspot.com/2009/03/weatherization-nation-how-i-reduced-my.html

    Worked for me.

    Link to this
  7. 7. JokerX 5:25 pm 04/29/2009

    I wouldn’t feel so down if I were the author. His "dilemma" of not being able to get any more significant gains from his energy efficiency quest simply means that he has done a bang-up job. He’s done his duty. The uncomfortable truth is that efficient use of energy is only part of the picture to a healthy environment. Clean, sustainable, and ample energy production is the other part, and that task falls to other entities besides Harry Homeowner.

    To those who say he should say damn the cost and buy expensive devices that will gain him only pennies a day in saved energy, get real. Maybe you should be so kind as to buy these devices yourself and mail them to him as a gift– anything for Mother Earth, right?

    Link to this
  8. 8. BC Green 11:00 pm 04/29/2009

    You are on the right track… Have a look at the overall efficiencies. The tankless heater is more efficient than a storage heater by up to 20% and it has a small added advantage in that it does not lose heat in stored hot water – but if the house is being heated, not air conditioned, the loss may add to house heat, and so it may in fact displace heating fuel…
    The real loss in domestic hot water is that almost all of the heat goes down the drain after a very short period of use. The heat escapes. So if 90% of the delivered heat is sent to waste, the difference between two heaters because of efficiency is not much when compared to the total.
    Domestic Hot Water is responsible for almost 50% of total heating requirements in hotels in a temperate climate (including cold winters). Like so many other initiatives, people want to do the right thing – and are given poor information.
    The only real solutions – either use a LOT less hot water – or recover the heat before it goes down the drain. I have seen a few places that use heat pumps to extract the heat and put it back into the water tank… but that is a solution that likely currently makes financial sense in larger buildings…

    The difference between tank heaters and tankless is small when compared to the loss down the drain… This needs a better solution that can be installed on a widespread basis…

    Link to this
  9. 9. ckmapawatt 4:25 pm 04/30/2009

    You forgot one of the most important steps in energy conservation: POWER MONITORING. If you aren’t actively monitoring, you aren’t actively trying to reduce consumption. I recently wrote a blog about one such product, The Energy Detective (TED):
    http://blog.mapawatt.com/2009/02/27/the-energy-detective/

    Link to this
  10. 10. BC Green 1:50 pm 05/2/2009

    Monitoring power is certainly valuable – but monitoring energy is another issue – and many people that I have seen that have a monitor for power love it for the first few weeks and then forget it. There are a number of surveys that show that the initial reaction is great – but it fails with time. The new initiatives to put time of use rates and interval meters that will allow displays are going to show this. Unfortunately, I note that the majority of US States have voted against this plan.

    There are a number of companies around that make a living on showing people what they use, and some even watch for you – identifying issues that may be causing problems. While I am a big fan of measuring and tracking savings (they need to be mearurable, manageable and reportable), the real need is to find systems that can be installed that do the hard work – and then track and optimize their results. The suggestion that measuring alone is a long term solution is simply not proving to be effective.

    Link to this
  11. 11. Gringa 8:26 pm 05/2/2009

    I used to live in South America, where tankless systems are the norm. It was also my experience that hot water flowed from the tap on-demand with no issues. Actually, with the storage systems here in the US, I find I have to let tap water run for a minute before the water turns hot. With the tankless systems in South America, the water turned hot almost instantaneously.

    Link to this
  12. 12. chrisneillsr 11:08 am 05/5/2009

    The Navien Tankless water heaters (A models)have a small 1 gallon tank built into it so you don’t have a minimum flow requirement, nor any cold water sandwich typical of most tankless water heaters today. Check them out at
    http://www.hookedonhydronics.com/navien-tankless-water-heaters-seattle

    Link to this
  13. 13. chrisneillsr 11:11 am 05/5/2009

    The Navien Tankless water heaters (A models)have a small 1 gallon tank built into it so you don’t have a minimum flow requirement, nor any cold water sandwich typical of most tankless water heaters today. Check them out at
    http://www.hookedonhydronics.com/navien-tankless-water-heaters-seattle

    Link to this
  14. 14. eco-steve 12:00 pm 05/13/2009

    I am installing a wood-fired stove to heat our house. That is carbon neutral except in extremely cold weather when it will need backing up by some oil. As to my car, I am trying to find a 1950 model that runs by pyrolysing wood, transforming it into hydrogen. There are still a few around, but sadly no new models are available. Then all that remains is to install solar panels on my roof. I am told they pay for themselves in 6 years…

    Link to this
  15. 15. srarts 8:33 am 05/1/2010

    Here’s more low hanging fruit on the hot water heater tree. One, wrap the tank with an additional layer of insulation, as in zacks’ suggestion . Two, get an off-peak electric meter installed. I have one and it’s great. The only thing on my off-peak meter is the water heater so it doesn’t have any power during certain periods of the day. The savings are high and the water temp. difference is negligible. Three, look into building your own solar water heater. Essentially, it’s a box of water tubing that faces the sun and soaks up all that energy during the day. It would probably cover most of your evening hot water needs.

    Link to this
  16. 16. srarts 8:34 am 05/1/2010

    Here’s more low hanging fruit on the hot water heater tree. One, wrap the tank with an additional layer of insulation, as in zacks’ suggestion . Two, get an off-peak electric meter installed. I have one and it’s great. The only thing on my off-peak meter is the water heater so it doesn’t have any power during certain periods of the day. The savings are high and the water temp. difference is negligible. Three, look into building your own solar water heater. Essentially, it’s a box of water tubing that faces the sun and soaks up all that energy during the day. It would probably cover most of your evening hot water needs.

    Link to this
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