Ovaltech III Greenhouse

The Ovaltech III from Harnois is low-maintenance, easy to erect,covered in polycarbonate film and includes a number of other features that leadto higher-quality plants. The Ovaltech III is the newest in the Ovaltechseries. It was introduced in 1999, offers more light transmission than previousOvaltech models and features straighter sides for maximum growing capacity.Here are some more details that will help you make an educated decision onwhich type of greenhouse structure might be the right fit for your growingbusiness.


The Ovaltech III’s gothic shape, combined with the use ofcurved purlins, makes the structure virtually dripless. It provides a largegrowing environment, with the highest light transmission of any of the Ovaltechmodels, and resists snow and ice accumulation. The Ovaltech III provides moreusable space than other structures because of its straighter sides, allowingfor more productivity and profitability.


This greenhouse is made of galvanized, large oval tubing,which, according to Harnois, is stronger than equivalent round tubing. Thegalvanized finish includes GatorShield and galvalume (steel protectioncoatings), and it can be customized according to use and location. All partsare pre-drilled and swedged for faster and easier assembly. “The structureis very easy to erect. One of the best features of the Ovaltech III is thecomplete plans, good inventory and easy-follow blueprints,” said RockKeitzer, owner of Keitzer Farms in Hartford, Mich., and owner of more than 50different Ovaltech models since the mid 1980s. Available in widths of 25, 27,30, 32 and 35 feet, it can be installed on a variety of foundations. TheOvaltech III also costs less per square foot than other Ovaltech models.


The Ovaltech III emphasizes natural ventilation. Thecombination of roll-up sides and ridge ventilation directs hot, contaminatedair outside the greenhouse, much like a chimney. Roll-up models can be up to300 feet long and up to six feet tall at the ridge on side- or butterfly-typeopenings.

According to Paul Connelly, owner of Connelly Greenhouses inThorndike, Maine, and of three other Ovaltechs in the series for more than 12years, “You need to break the vent in — it is a little stiff atfirst, but overall it is very useful.” This system, combined with thegreater air volume of the greenhouse, provides a more even climate, with lesstemperature variations than traditional forced-air ventilation. In theconstruction of the structure at Keitzer Farms, a heater was added, but therest of the materials were part of the package. Furthermore, naturalventilation, whether motorized or manual, requires less energy and will help inpreventing the spread of diseases and pests. Natural ventilation is better forthe crops and costs less to operate than traditional mechanical ventilation.


With a clearance of a little more than nine feet from groundto cross-tie, the Ovaltech III has ample headroom for comfortably workinginside the greenhouse, even with baskets hanging on the cross-ties. Connellysays, “There is very little maintenance with the Ovaltech III, but makesure to change the film every four years. I have polycarbonate film in thefirst 24 feet of my greenhouse, and it seems to hold up the best within thefirst four years.” The structure can be covered with single or doublepolyethylene film, or with corrugated, 8-mm polycarbonate sheets. “Thequality of this unit, simplicity of the structure and the delivery are the mostimportant characteristics of the Ovaltech III,” said Keitzer. The OvaltechIII is more than 25 percent stronger than regular round-tube structures,according to Harnois.

Final Words

According to the manufacturer, the Ovaltech III is viewed bymany growers around the world as the simplest and most efficient greenhousethey have ever had. Growers say the Ovaltech III embodies perfectly thephilosophy that animates Harnois Industries: being innovative, daring to bedifferent and providing simple solutions to create perfect growing environmentsfor each specific customer. “Overall, Harnois is a good company with areliable product and organization, quality and delivery that is far better thanother greenhouse structure manufacturers,” says Keitzer.

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