Bench Heat: 6 Things To Know
Bench heat offers energy savings and healthier plants.

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.

Fuel prices are low, and now can be a great time to invest in a bench heating system. The money you’re saving on today’s energy bills can help fund the investment of the new system, so you’ll be prepared with an energy-efficient heating solution when fuel prices do increase again.

Here are six things to know about bench heat and its benefits:

Under-bench heat provides warmth at the root zone, promoting faster germination.

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.

Weed barrier covering the manifold helps spread the heat.

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:

• Growers using EPDM rubber tubing or fin tubing can benefit from keeping the bench full of plants, which helps provide uniform heat. A weed barrier mat can also be used to cover the bench and spread the heat.
  
• A chimney effect can occur if there’s a gap in the plant canopy. This can allow heat to escape. Using 18-inch-high skirts around the bench sides can help prevent under-bench heat from escaping.²
  

Learn more about hydronic heating at www.deltatsolutions.com. Contact us for a personalized analysis of your heating needs. Call 800-552-5058 or email info@deltatsolutions.com.

1 “Exploring Underbench Heating Options,” Greenhouse Product News, October 2006
2 “Root Zone Heat - Installation Techniques,” UMass Extension