
Reid's water heater
By Reid Oechslin
This winter I tried some ideas I’ve had for saving energy in my home. They may be a little odd, and they certainly wouldn’t apply to everybody. They’re things I’ve thought about as I was falling asleep or waking up. Ideas that come to me that way can either be great or terrible. I will spare you the terrible ones, and try to pass along the keepers. It’ll take me several articles to do it.
My family lives in a split-level house built in 1972. It was an amazing time. America could fund the arts, send men to the moon, fight the Vietnam War and build the interstate highway system. People were regularly predicting that energy would soon be “too cheap to meter.” Our 3000 square-foot house has a 600 amp electrical service–that’s three times the size of the power panel in new homes–because it has an electrically-heated driveway! (Or it HAD an electrically-heated driveway–I turned it on once after we bought the house and I heard sparking noises coming from the grass around it. I decided to take pity on the neighborhood dogs and turned it off permanently.)
Along with our interesting driveway feature was another convenience: no matter which hot-water faucet you turned on in the house, you’d have hot water within a few seconds. Remember, it’s a split-level, and it’s a long, narrow house, so the gas water heater is really far from the bathrooms that serve the bedrooms. How’d they do that? I did some checking and found that instead of two pipes connected to my hot water heater, I had three: one for the cold water to go in, one for the hot water to go out, and another for the cooler hot water that flowed in a loop past all the faucets to go back into the hot water heater. Hot water was slowly circulating through the pipes in my house all the time, so hot water was only a few feet away from any faucet. The really hot water would flow out of the top of the heater, through the hot water loop, and, since it was cooling off as it made its way through my basement and the uninsulated ceiling of my cold garage, it would be slightly heavier than the newly-heated water when it returned to the bottom of the water heater. No pumps, just convection. Brilliant–no wasted water going down the drain, and no wasted time waiting for hot water to arrive. Except–my hot water heater, with its nice blanket of insulation, was not the only repository of my hot water. It was as if the uninsulated hot water pipes were little radiators heating the basement and the garage. That’s really not where I wanted to put my heating dollars, so I closed the valve where the cooler water went back into the water heater. (If you’re curious about what orifice the cooler water uses to go back into the heater, it goes back in through the valve at the bottom that you use to drain the tank.)
Almost immediately I got negative feedback from my wife: “We don’t have any hot water!” After I explained what I had done and why, she still didn’t like the idea of the wait, and the idea of wasting the water that comes out as you wait. (She is from the Caribbean, where rainwater is collected in cisterns, and there is no other water supply. If you run out, you call the water truck to make a delivery, which is expensive. It’s a system that stresses personal responsibility.) I did feel guilty about the water that was wasted, and decided to measure how much water was going down the drain during the warmup. It turned out to be, at most, two gallons. What to do about that?
I decided that if the pipes were insulated, the water in them would stay hot longer. I couldn’t reach everything to insulate it, but was lucky that the ceilings in part of the downstairs areas and the garage were suspended tiles–I suppose to make maintenance and repairs easier. I found that the cheaper, stiffer kind of foam pipe insulation worked better, because after you snap it around the pipe, you can push it along the pipe with another piece of insulation, even into areas that you can see but can’t get to. And the insulation did turn out to work somewhat– if you open a faucet up to two hours later, what comes out is at least warmer than it would have been, and the new hot water coming up the pipe isn’t trying to warm up every foot of that pipe from, say, 50 degrees. It certainly doesn’t work for the first shower of the day, though.
I did some rationalizing–the waste of water is not as bad as the waste of energy and the greenhouse gas emissions from the water heater. My best guess was that the insulation and the circulation change saves 15 percent off the gas bill. At my house, that’s 30 bucks a month, at least during the winter months. It will probably be less of a difference in the summer, when the basement and garage are warmer and robbing less heat from the pipes. Still, well worth doing. What could be easier than closing a valve?
You probably don’t live in a house that has recirculated hot water, and you probably don’t have as much access to the pipes as I do, but you do probably live in a house that has bare copper pipes sticking out of the top of the water heater. Even insulating the first few feet of that pipe–that is constantly radiating heat away from the hot water tank–will make a difference. Most likely, you don’t spend a lot of time next to your water heater, basking in the heat it is radiating.
Note that if you have a gas water heater like mine, the gas flue chimney is very close to the cold and hot water pipes that come out of the heater. Don’t use plastic foam pipe insulation next to that flue, because of the risk of fire. Instead, use fiberglass that won’t burn. The cheap fiberglass solution is just a band of the fuzzy insulation itself, with no backing, that you wrap around the pipe. It works, but for a little more swank factor, you can buy tubes of pre-formed fiberglass that fits around the pipe like a clamshell (buy the right size to fit around the pipe, usually 3/4″). It has a white outside coating, and even a self-adhesive flap that makes it neat. In this area, Home Depot and Hajoca carry it; Lowe’s does not. Next time I’ll tell you about my 1972 furnace and what I did to it.
Copyright 2010 Reid Oechslin
Reid is a SG2020 steering committee member and owner of Sound Light Image, LLC.