Dordt College News

Timmer demonstrates a residential solar-assisted hot water system

August 17, 2011

For the past two years, Engineering Professor Kevin Timmer and several of his students have been designing, building, and testing a residential solar-assisted hot water system.

Their work has been funded in part by a small grant from the Iowa Energy Center. In late April, Timmer gave a demonstration of the system along with a presentation on household energy stewardship to the public.

The solar-assisted hot water heater has two solar collectors on the roof. Piping filled with antifreeze heated by the sun runs down and around the inside of a storage tank, heating the domestic water.

“Studies show that these types of systems should be economically feasible as far north as Minneapolis,” says Timmer.  Overall, the system would supply nearly all household hot water in the summer and about 20 percent of hot water in the winter in northern climates, or an average of 50 percent of annual energy use for heating water. When it is too cold and cloudy, the system shuts off.

Professor Kevin Timmer with the solar panels on the roof of the Science Building. Pipes filled with antifreeze heated by the solar collectors heat the water in this water heater in the building's basement.Like many research efforts, the project ran into a snag early on, causing Timmer to ask for an unfunded extension for the grant. Two students originally designed and built the unit but found that parts of it kept leaking. They had begun with a kit, manufactured in Europe, and modified it to suit their purposes. It wasn’t until Timmer spent time poring over the kit’s manual that he realized that the threading on three-quarter-inch piping supplied with the kit conformed to a European standard (BSPT) and had an angle five degrees different than the piping purchased here (NPT) to supplement the kit. The threads were also rounded on top rather than flat. These minor differences made a big difference during assembly. Sometimes the mismatched threads sealed and sometimes they didn’t. Once they diagnosed the problem, the team's work proceeded smoothly.

“When you are learning plumbing and you have leaks, you naturally assume you did something wrong. It was nice to find out that we could blame the Europeans instead!” chuckles Timmer.

Compared to relatively inexpensive traditional means of heating water, the system is marginally cost-effective because it would take almost the life of the system to pay back installation costs. But as energy costs continue to rise, the payback time will be less. “And heating water with solar energy helps save nonrenewable fossil fuels for things that require highly concentrated energy like refining steel,” says Timmer.

“It makes sense to develop ways to use solar energy for things like heating our water rather than using fossil fuels which are capable of producing very high temperatures,” Timmer says.

There’s also another way to think about such efforts: “If we charged consumers the real cost of fossil energy, solar water heaters would not look expensive,” Timmer says. At present we do not count in our energy costs the subsidies given to energy companies or the military costs of protecting our supply of oil in unstable countries.

“We pay for part of our energy with taxes, not at the pump. And in the meantime we keep making infrastructure decisions that tie us into artificially cheap energy for the next 50 to 100 years.”

Iowa Energy Center grants help fund small research efforts, like this one by Timmer and his students, on renewable energy, and as part of the grant they require the researchers to give a public presentation of their results to help people in local communities think about ways they can use renewable energy sources.

Timmer shared both what he and his students had learned about solar-assisted heating of hot water and shared some ways people can think about using different forms of energy in their homes. He described passive solar options, LED lighting, and photo voltaics (a method of generating electrical power by converting solar radiation into direct current electricity).

“Our homes and businesses consume nearly 40 pecent of the energy we use in this country,” says Timmer. “Being wise stewards of that energy is a big deal.”

Timmer is committed to exploring renewable energy uses and encouraging his students to do the same. Over the past two years, five students have benefitted from the employment opportunity they had because of the grant and, in the process, they learned a great deal about renewable energy—and plumbing.


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