Prior to the Thermal Battery System retrofit, this 3500 square foot home was heated with a propane forced air furnace and used 800 to 1000 gallons of propane per year. The homeowner utilized a drain-back, 4×8 flat plate solar thermal collector system for domestic water.
The homeowner wanted options to reduce propane usage but had reached the conclusion that conventional geothermal would not be an acceptable solution. There was not sufficient water available for an open loop, closed loop horizontal was too invasive to the sensitive desert landscape and closed loop vertical was not only too invasive but too expensive as well.
Finding a better solution…
Steve from Harmony Heating and Solar, the installer of the original solar thermal collector system, immediately recognized the merits of a “hybrid” approach for his customer. Thermal Battery System, Inc. worked closely with Steve to design a system that would be cost effective and reduce propane usage while conserving the delicate desert landscape.
During the proposal to the homeowner, it was made clear that this system design was unconventional and it was a very significant deviation from industry standards. The homeowner was excited to be a pioneer of a newly developing renewable energy frontier. We were excited to have such an enthusiastic early adopter on our team. Over the next year, Thermal Battery Systems set out to demonstrate a new solution to the geothermal industry.
In the fall of 2011, Harmony Heating installed a 2500 gallon Thermal Battery that has three 700′ sections of 3/4′ poly pipe, piped in parallel inside the tank. Two more flat plate collectors was added to the existing solar array and a flat plate heat exchanger in the primary/ drain-back loop was installed. One 300′ borehole was drilled for the sole “geo” capacity. The heat pump is a five ton split system so the “A” coil simply got installed on top of the existing furnace. If the system was to become fully depleted or if something mechanical broke the propane furnace could provide back up heat.
There was no shortage of skepticism from onlookers. Many were convinced that our “hybrid” system wouldn’t work, that these types of systems had been tried before, that IF these systems did work more would be currently being installed. We did not get discouraged–after comparing the details of this system design to those tried before, we were secure in our knowledge that this system was completely different–in fact, this was the first latent capable thermal battery system ever installed.
As of 2014, this system has not only worked for the past three years, it has entirely eliminated the home’s propane usage (except for cooking). During the winter of 2013-2014, the homeowner saved over $2,671 in heating costs! As you may remember, the cost of this system after tax credits was $17, 150, which means it would take 6.5 years to achieve “pay back” on this system.
In 2013, the homeowner decided to install a P.V. system that site generates approximately 10,000 KWH–over the KWH of the entire home usage, including the heat pump mechanical system, effectively achieving net-zero status!