Direct-fired heating system proves safe, efficient, according to study

Washington -- L.B. White’s Therma Grow propane-fueled direct-fired heater system is up to 11.6 percent more efficient than certain indirect-fired models, according to a study recently conducted by the Ohio State University and funded by the Propane Education & Research Council (PERC).

The study also concluded that the Therma Grow system does not cause plant damage, according to a PERC press release. The trial compared the Therma Grow system with an indirect-fired model and took place in two separate 24 by 48 foot double-poly greenhouses.

During the trial, scientists monitored fuel consumption, relative humidity, temperature, CO₂ and ethylene in both greenhouse environments. The greenhouse using the Therma Grow system reportedly used 11.6 percent less fuel than the greenhouse with the indirect-fired heater.

The reduction in fuel consumption is the result of Therma Grow’s heat combustion design, which converts almost all fuel energy into useable heated air, according to PERC. While an average vented heater is able to convert only 80 percent of its given fuel into usable heat, the Therma Grow is able to convert 99.9 percent.

Assessing plant damage
Along with monitoring fuel usage of the two houses, six plant varieties were tested during the study for signs of damage and overall quality. They were tomato, zinnia, marigold, impatiens, snapdragon and petunia plants. Researchers monitored plants for symptoms of off-gas damage as well as pests, diseases and signs of phytotoxicity throughout the experiment. No damage or other issues were reported while using the Therma Grow system, according to PERC reports.

The study does not validate all other direct-fired heaters as being plant-safe. The study only tested the Therma Grow system.