Space heating in Maine is costly and expected to cost much more in the future. No matter how you get your space heating BTU's, one can expect to pay more for them, unless you can use the sun. In an effort to minimize our heating costs, MOFGA is developing a plan to use the sun to lower our water and space heating costs.
Main Building: Plans now are for flat-plate collectors to be installed on the south side of the main building, most likely as a "solar wall." A solar wall will take advantage of snow reflection during the winter, be easier to maintain, as well as allowing fairgoers to get a close up view of this heat generating system. The water in these flat plate collectors will be pumped to MOFGA's existing 1500-gallon insulated water tank. This tank is already part of our present heating system, which will need some minor modifications to take advantage of the new water temperatures in the tank. This set-up will also require some reworking of our existing radiator system.
Hot-Water: We plan on installing a propane fired on-demand heater in the kitchen with a possible solar collector as an assist. Hot water now has to travel a long distance to the kitchen and depending on the heat demands that day, may not be hot enough for all purposes.
Sprinkler Building: The main building at MOFGA was required to have a large sprinkler system. As a result we have a sprinkler building with three very large steel tanks filled with water we must heat to prevent from freezing. This situation presents a challenge to reducing our use of petroleum products.
Fortunately, the sprinkler building is an ideal application for solar heating for two reasons:
- The building only needs to be kept above freezing. This means the collector operates at low temperature, which means higher efficiency and wood components can be used.
- The water in the tanks provides a large amount of thermal storage to carry over solar energy collected on sunny days into nights and cloudy days.
We looked at several methods of capturing the sun’s energy to keep this water from freezing and decided on a wall collector. A wall collector provides a better collector angle to the fall, winter and spring sun than a roof collector. It is also easier to cover in the summer to prevent over heating.
We first investigated purchasing pre-built solar collectors, but decided to construct our own. Site built collectors can be lower cost, designed to maximize use of available south facing area, and more aesthetic. All materials were available locally except the polycarbonate glazing.
Door, windows, and siding removed from south wall and openings covered with plywood.
Vertical slots cut at extreme east and west ends of south wall to provide air inlet and outlet for collector.
The slot is extended through the 6” insulated wall with short masonite ducts.
2 x 4 perimeter frame screwed to wall.
1/2” foil faced foam insulation applied and joints sealed with aluminum tape and caulking.
Stand offs made from strapping screwed to wall to support the metal collector plate and provide a space for air to move behind the plate. Metal plate (standard 3’ wide black steel roofing) screwed to stand offs and sealed with caulking.
Vertical glazing supports screwed over the plate.
Bottom and side perimeter covered with aluminum flashing.
Polycarbonate glazing installed with weather stripping and aluminum battens.
Inlet manifold and fan installed. Differential controller turns on fan when
collector is 20 degrees hotter than the building.
For more details on design and construction of site built collectors contact Jay LeGore: firstname.lastname@example.org.