rates. Those energy savings are equivalent to about 136 gallons of fuel oil, or 165 therms of natural gas.
Chances are your present system is now wasting a similar amount of fuel. No batch heater -- or any other solar hot water system -- will work to its full capacity until this enormous waste has been dealt with.

Your Batch Heater

As you no doubt noticed when you read through this list of design considerations, the batch heater we've designed is unusually sophisticated. It employs a single, vertical tank for simplicity and good stratification of the water, triple glazing and a selective surface to avoid the complications of a movable insulation system, and a cusp-shaped reflector to boost collection efficiency.  It's a flexible design that can be adapted to any one of the mounting options shown in the diagrams: in a greenhouse, on an exterior wall, or freestanding. Among the do- it-yourself systems available, we believe our design offers an unbeatable combination of cost, performance, and foolproof reliability. Best of it all, it's not hard to build.
The next few pages show you how.

Here's How to Build Ours

In preparing these step-by-step instructions, we've divided the construction and installation of our batch heater into essential and non-essential procedures. 
The essential procedures (and the ones we'll be spending most of our time dealing with) are: plumbing and mounting the batch heater's tank (including installation of a "selective surface" absorber coating); constructing the sophisticated cusp-shaped curved reflector frame; building the supporting frames that house the reflector; constructing our special, low-cost triple-glazing system; and connecting the hatch heater to your existing water supply.
When you've completed these essential steps, you'll have a working batch heater like the one shown in Illustration A, plus the additional subassemblies as shown in Illustrations E, F, G, and H. The only thing your batch heater will lack is its outer "skin," that is, its exterior enclosure. From a technical standpoint, the exterior enclosure is the least important part of the batch heater. Most of the decisions regarding the enclosure are aesthetic, and have more to do with your taste, budget, and imagination, than with any element of the batch heater's performance. For example, if low cost is your primary objective, you can sheathe the assembly shown in Illustration A with plywood, and mount it on a simple, angled frame of two by fours or pressure-treated posts. (This type of freestanding mount was shown in Illustration C in the previous article.) The total mounting costs could be as low as $50. Or, if you prefer, you can mount the batch heater in a custom enclosure much like the one shown on our front cover, matching your home's existing siding and trim for an eye-pleasing "built-in" appearance. Or, by enlarging the enclosure, you can build the batch heater as a freestanding tool shed, and use the space beneath the batch heater for storage. Or you can add it to a garage, or a workshop... the list of options is almost endless.

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