Bench Heat: 6 Things To Know
by Michael Kovalycsik, National Sales & Marketing Director, Delta T Solutions
Providing even warmth in the root zone has proven benefits, including quicker turns and reduced energy use. But, it’s difficult to achieve this type of even heat at the soil level using traditional unit heaters. With hydronic bench heat, water is circulated through tubes installed on top of or under benches, providing beneficial warmth at the root zone.
Here are six things to know about bench heat and its benefits:
1. Soil Temperature Rules
For most crops, the soil temperature is more important to the health and growth of the plant than the air temperature1, according to John Bartok, extension professor emeritus and agricultural engineer, Department of Natural Resources and the Environment, University of Connecticut. When using bench heat, the temperature of the greenhouse can be lowered by as much as 15 degrees below the soil temperature without adversely affecting the plants. A root zone heating system can provide 25% to 75% of a greenhouse’s total heat needs.2
2. Save on Fuel Costs
Bench heat offers fuels savings not just because greenhouse ambient temperature can be lowered, but also because root zone heating results in accelerated rooting and faster growth and turns.
3. Rugged Design for Greenhouses
EPDM rubber tubing used in bench heating is highly durable due to its resistance to temperature and chemicals. Delta T Solutions’ DELTA-TUBE SD EPDM rubber tubing has a small diameter tube, which reduces water volume, enabling the system to respond quickly and efficiently. This type of tubing works especially well for propagation and containers, according to Bartok.
4. Warm Up with Radiant Heat
Aluminum under-bench heating, such as the DELTA-FIN TF2 system, heats the air surrounding the pipe, distributing warmth to the soil, roots and foliage through natural convection and radiant heat. Bartok recommends insulating the pipes that carry water to further energy savings.
5. Reduce Chance of Disease
Heating at the root zone can help dry soil faster, reducing incidences of fungal disease.
6. Even, Uniform Heating
Bench heat allows for a more uniform heat pattern compared to unit or perimeter heaters.2
Bartok offers a couple of other tips for getting the most out of a bench heating system:
1 “Exploring Underbench Heating Options,” Greenhouse Product News, October 2006
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