Hydronic Seed Dryers

I have designed two hydronic (water-heated) seed dryers for Wild Garden Seed.  Contact me if you are interested in either of the designs below or a custom design for your seed/other drying needs.

Advantages of hydronic heating:

  • Even heat throughout
  • Avoid scorching/overheating – no point is warmer than the water temperature of 110º-130ºF
  • Reduced fire hazard vs. combustion-fired or electric-heated dryers
  • Possible integration with existing hydronic greenhouse bench heating or indoor hydronic heat.


Greenhouse dryer

Dryer configuration: four shelves stacked, doors on, heat table supply pipes capped.
  • Four shelves, 3′ x 16′ with Delta-T(TM) heat transfer tubing and manifolds.  Three of the four shelves are removable; the system converts from 192 sq. ft of drying area in summer/fall to 192 sq. ft of heated bench area in winter/spring.
  • Off-the-shelf 4500-watt electric water heater as heat source, 130ºF water temperature.
  • 16 drying screens, 3′ x 4′, four magnetic doors for easy loading/unloading.
  • With doors removed, functions as 4500-watt space heater on cold days.
Hot table configuration: doors off, supply pipes connected, four shelves side by side.


Indoor model

  • Shape/size customized to fit in available space.
  • Over 300′ of PEX tubing provides very efficient heat transfer: 110ºF water temperature will maintain 85ºF air temperature.
  • Enclosed fan and ducts on three sides create steady, one-directional airflow across drying screens.
  • Twelve drying screens, 26″ x 30″, total 65 sq. ft. drying area.
  • Heat source is 2000-watt, 120V electric water heater.
  • Doubles as 2000-watt space heater when vents fully open.
Dryer under construction, showing PEX tubing, screen supports, and bottom/side ducts.
PEX loops in end ducts.


Loading screens with bronze fennel seed for drying.