Scratch Bakery Solar Hot Water System a Statement to the Community
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For Bob Johnson at the Scratch Baking Company, solar hot water was a matter of “very simple math.”
With a modest investment in a solar hot water system, his business could “take a pretty big chunk out of our carbon contribution as well as save money by using less gas to heat hot water.”
With such a nice intersection of environmental stewardship and economics, it was simply a matter of finding the funds to invest in the system.
“Based on our calculations, the payback [for the system] would be relatively short, but we still wanted to find some sort of grant or partial financing so we would not have to take the full cash hit on the install,” Bob says. “ReVision’s staff was on top of this goal and advised me last fall that there was a Commercial Projects Grant available for solar energy projects of our size and scope. This was a Federal grant administered by Efficiency Maine. Jen (from ReVision) and I partnered in putting the grant together and it was awarded to Scratch in February.”
Make Hot Water While the Sun Shines
ReVision Energy co-founder Fortunat Mueller, one of the leading solar thermal experts in the northeast, designed a 120-tube solar hot water system with a Rinnai Continuum natural gas on demand hot water heater serving as backup. When the sun is shining, sun-heated antifreeze pumps from the rooftop collectors through a heat exchange coil at the bottom of a super-insulated storage tank, producing domestic hot water for Scratch.
When someone in the bakery turns on the tap, water flows from the solar tank and through the Rinnai hot water heater. If the water temperature is above a pre-determined setpoint, the Rinnai does not fire up at all. If the water needs to be warmed by a few degrees, the Rinnai is able to fire up to provide just the amount of heat required to get the water to the appropriate temperature.
The system has been living up to expectations, allowing Scratch to seriously benefit from the solar spill we experienced in May. So far Bob estimates that the hot water system has reduced his natural gas usage by more than 25% during the first month that the system was installed.
“I go down to look at the tank temp every morning when I get to work,” he says. “If the day before was a sunny day, we will be sitting on 210 gallons of 145 deg. water that we will need to blend down to 120 deg.”
But it’s the environmental benefits that excite Bob the most. “I believe Scratch is a perfect application for this kind of technology, and being a neighborhood bakery that is a values driven business, a very good use of these kinds of funds. And because of our location and customer base, we have a real opportunity for educating people about what is possible with solar.”