Our customers Ron and Sandra have a large family, but limited roof space, which made it a challenge to fit a solar hot water system on their roof that would meet their needs. Evacuated tube solar hot water collectors, though more expensive than flat plates, are able to provide more heat per square foot of collector and thus were a good match. Evacuated tubes’ superior collection power is made possible by a vacuum that surrounds the collector in each tube. Similar to a Thermos, the vacuum ensures there is virtually no heat loss once the sun hits it.
Drain Back Design
The solar fluid for all solar hot water systems need to be protected from summer-time over-heating and winter-time freezing. To this end, we chose to implement a drain back design for Ron and Sandra. This means that when the system is off all of the solar fluid automatically falls back into a holding (drain back) tank in the basement, and the air that was in the drain back tank rises up into the collectors. The collectors themselves are designed to withstand the heat that they create.
Smart Hot Water Recirculation
Ron and Sandra enjoyed having hot water come quickly to their faucets because there was a recirculation loop that circulated hot water constantly through the pipes and back to the tank in the basement. Running a recirculation loop all the time, however, uses a lot of fuel and electricity. So we upgraded the system to one which uses a switching mechanism that is simply controlled by momentarily turning any hot water faucet on. The recirculation loop is then activated for a short period of time—enough to flush the cold water out of the lines.