Western Larch, © George Wuerthner
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By Andy Kerr This is our third solar-hot water heater, having installed Copper Crickets in previous houses in Joseph and Portland. Copper Crickets are no longer manufactured. The Ashland system was installed March 30, 2001.
As the sun begins to heat the Radco 4-feet by 12-feet solar collection panel (front and center), it also begins to shine on a Solarex SX-30 30-watt DC photovoltaic panel (on other roof pitch) that powers a 12-V DC, 1.5-amp, 1850-RPM motor which circulates 2.5 gallons of non-toxic propylene glycol antifreeze solution in a closed loop that includes the solar collection panel and ...
... the heat exchanger unit inside the Rheem Solaraide 80-gallon solar hot water storage tank. The tank has R-16.7 insulation. Cold water from the street is preheated in the solar hot water heater tank (left) and then flows into the previously existing electric hot water tank (right). The plumbing above the tanks includes five valves to allow either the solar hot water tank (in case of system failure) or the electric hot water tank (in case of summer) to be bypassed. There also a heat trap to minimize heat loss and mixing valve to prevent scalding. Temperature gauges indicate (1) temperatures of glycol in and out of heat exchanger in solar hot water tank; (2) temperature of water out of solar hot water tank into electric hot water tank; and pressure of glycol loop. A flow-meter is inserted in the closed loop. Safety features include pressure-temperature relief valves on the solar hot water tank (drains outside like the electric hot water tank pressure relief valve) and the glycol loop (drains into floor overflow pan under solar hot water heater). Timer Switch An Intermatic EH-40 240 V DPST 7-day control timer allows the electric hot water heater to remain off except when it is needed. Having a hot water heater on all the time is like leaving your car running in the garage at 3 AM because you might want to use it. The timer is set to provide for morning showers and evening baths. The water is hot enough for dishes anytime. In cases of heavy demand, such as laundry or guests, the an override switch leaves the power on until reset.
According to the State of Oregon Energy Office:
Given the sunnier climate of the Rogue Valley vis a vis the Willamette Valley, I'm estimating that the system will provide three-fifths to two-thirds of our annual hot water demand.
Source: Oregon Energy Office Web Page Though Ashland is a bit sunnier than Medford (such measurements are done at the Medford airport, noted for being the foggiest place in the Rogue Valley), let's use the 2,600 kWh of annual energy saved noted in the above graph.
Ashland's water is pure; so scale build-up isn't an issue. In about five years the anti-freeze may discolor indicating breakdown due to excessive heating and need to be replaced (estimated cost: $100). Mostly, one can just enjoy peeking at the temperature gauges occasionally.
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