greenhouse air circulation and venting

Greenhouse Ventilation: Negative Air Pressure and Passive Systems

With negative air systems, warm air is sucked out with exhaust fans - air intake is through shutters. Sizing of equipment will depend upon the greenhouse dimensions, the season of the year, the crop and the transpiration rate of the crop.

Passive systems use roof vents and wall openings; air flow through a vent can either be up (warm air rising) or down (cold air dropping). Conditions at any given moment will determine the direction.

Outside wind and interior air circulation (typically horizontal air flow, HAF) will influence the performance of both negative air and passive systems.

The two systems can be used in the same greenhouse - but not at the same time. Negative systems require restricted air intake openings to achieve air flow speed. Because of this, open vents or sidewalls make exhaust fans almost completely ineffective.

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Timer Control Box for Light Dep

Price: $1,075.00

24 hour timer unit for roll up shade systems (Call for a quote) used to adjust the photo-period.
Allows for several openings and closings in a 24 hour period - the benefit is that the curtain can be automatically raised after the sun sets. GREENHOUSE USE ONLY.

Incremental Controller for Roll Up Motors (computer input)

Price: $1,048.00

Automate your roll up walls for a more consistent environment and crop.
Operates 2 roll up motors - they plug into any standard 110v. outlet. The motors are individually fused.
The incremental controllers energize every 10 minutes (adjustable), if the temperature is above the set point, the wall rises 6" (adjustable).
If the temperature is below the set point, the wall drops 6".
Limit switches on the motors determine the lower and upper travel of the motors.
Model VEC-CI interfaces with most standard greenhouse computer controls (Argus, Priva, etc)
CSA pre-approval (VEC-CSA) is available as an option.

Incremental Control Box for Roll Up Motors (thermostat input)

Price: $1,038.00

Automate your roll up walls for a more consistent environment and crop. Operates 2 roll up motors - they plug into any standard 110v. outlet. The motors are individually fused. The incremental controllers energize every 10 minutes (adjustable), if the temperature is above the set point, the wall rises 6" (adjustable). If the temperature is below the set point, the wall drops 6". Limit switches on the motors determine the lower and upper travel of the motors. Model VEC-TI is controlled with a thermostat (not supplied - see product code VETH) GREENHOUSE USE ONLY.

20" Shutter-Style Exhaust Fan

Price: $625.00

Schaefer SFT-2000A 20" Shutter-Style Exhaust Fan, great for greenhouses . Low-maintenance, energy-efficient solution for low to medium airflow. Features an aluminum blade, powder-coated guards, durable aluminum shutters and an enclosed heavy-duty motor. Hardwired electrical connection required. Mounts flush to exterior wall.

Features and Specs:

Speed: RPM 14
Air Delivery: CFM 3,122
Volts: 115/230
H/P: 1/3
Amps: 3.8/1.9
Dimensions: L x W x H 12 ⅜" x 22 ¾" x 22 ¾"
Made in United States

12" Air Circulation Fan

Price: $335.00

Good air circulation creates temperature uniformity, reduces temperature stratification and promotes evaporation from the leaves (to lessen disease).
We offer Schaefer fans - engineered for high performance and longevity. Air is thrown in a tight conical pattern, ideal for horizontal air flow (HAF) applications. Two year limited warranty.
.1 HP, 115/230 volts (1.3/.65 amps) 1554 cubic feet of air per minute

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Greenhouse Light Dep Roll Up Motor, 156 nM

Price: $290.00

Use with roll-up walls.
Excellent reliability. Ideal for light deprivation and blackout systems.
24 volt DC motor, comes with built in limit switches. Torque: 156 Nm* - RPM: 2.2 - Amps: 4 max (7 amps max. load) Revolutions : 40 max - Weight: 4.6 kg. Comes with a coupler 1 3/8" roll up tube. Controllers not included.

*A netwon metre is a unit of torque in the metric system. 156 nM = 115.06 ft-lb.

Aluminium Shutter, 30"

Price: $275.00

Brushed aluminium. Automate with shutter motors (requires a thermostat or other controller - not included ) or VEL thermal opener.
rough opening: 30 1/2" wide X 31"

Motor for Aluminium Shutter

Price: $268.00

Automate any shutter up to 48"

8" Air Circulation Fan

Price: $235.00

Good air circulation creates temperature uniformity, reduces temperature stratification and promotes evaporation from the leaves (to lessen disease). We offer Schaefer fans - engineered for high performance and longevity. Air is thrown in a tight conical pattern, ideal for horizontal air flow (HAF) applications. Two year limited warranty. .1/100 HP, 115 volts (0.6 amps) 450 CFM air delivery

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Greenhouse Electric Roll Up Motor, 44 nM

Price: $198.00

Use with a roll up wall 100' or less.
Excellent reliability. Ideal for ventilation, light deprivation and blackout systems.
24 volt DC motor, comes with built in limit switches. Torque: 44 Nm - RPM: 4.5 - Amps: 2 (max: 4) - Revolutions: 40 - Weight: 3.5 Kg
Both couplers are used with 1-3/8" outside diameter tube.
Various install kits and controllers, sold seperately.

*A netwon metre is a unit of torque in the metric system. 44nM = 32.453 ft-lb.

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