US20080096482A1

US20080096482A1 - Fan controller

Info

Publication number: US20080096482A1
Application number: US11/874,333
Authority: US
Inventors: Ola Wettergren
Original assignee: Fantech Inc
Current assignee: Fantech Inc
Priority date: 2006-10-18
Filing date: 2007-10-18
Publication date: 2008-04-24

Abstract

A fan control system includes a main fan controller and at least one auxiliary fan controller. The main fan controller has circuitry for running a fan on a preset cycle, the preset cycle having a preset speed for a preset time. The main fan controller is associated with a first space having a first ventilation port in communication with the fan. The at least one auxiliary fan controller is associated with a second space having a second ventilation port in communication with the fan. Each of the main fan controller and at least one auxiliary fan controller has circuitry for activating the fan to run on a temporary cycle having a temporary speed for a preset time. Each of the main fan controller and at least one auxiliary fan controller further includes an indicator for displaying activation status of the temporary cycle.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The benefits of U.S. Provisional Application No. 60/862,035 filed Oct. 18, 2006 and entitled “Fan Controller” are claimed under 35 U.S.C. § 119(e), and the entire contents of this provisional application are expressly incorporated herein by reference thereto.

FIELD OF THE INVENTION

The invention relates to a fan controller for use with a fan such as an inline fan disposed in ductwork.

BACKGROUND OF THE INVENTION

Indoor Air Quality (IAQ) is a term with which those in the ventilation equipment industry are very familiar. Awareness of IAQ among customers is increasing everyday. Consumers are learning about the importance of IAQ in terms of health and comfort. The market demands that homes are constructed in such a manner that IAQ is optimized to provide a healthful and pleasant living environment—it needs scarcely to be mentioned that the home is the space where we spend most of our lives.
Home building technology has advanced considerably over the past thirty years. Superior construction materials and techniques are now employed making homes much more efficient than they were in the past. Part of this new efficiency is derived from having a tighter building envelope. This means, of course, that exchange between stale inside air and fresh outside air is less likely to occur passively.
Air naturally contains contaminants. Humans tolerate these contaminants when their concentrations are at normal levels. Elevated contaminant concentrations occur when we share our living spaces with pollutant producing sources. The indoor environment becomes less comfortable when organisms (such as ourselves) consume oxygen from the air and add carbon dioxide to it through normal respiration. Activities such as bathing and cooking are detrimental to the quality of the air inside our living environment as well.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has recognized the importance of IAQ. ASHRAE Standard 62.2 was written to define the minimum requirements for mechanical and natural ventilation systems intended to provide acceptable IAQ in low-rise residential buildings. In addition to providing guidance for good practice, municipalities across the United States and Canada are adopting ASHRAE Standard 62.2 as the basis for the sections of their building codes that address residential ventilation. ASHRAE defines acceptable IAQ as: “Air toward which a substantial majority of occupants express no dissatisfaction with respect to odor and sensory irritation and in which there are not likely to be contaminants at concentrations that are known to pose a health risk.”
AIR EXCHANGE: The best way to improve IAQ in a home is through air exchange—by replacing some of the contaminated inside air with fresh air from outside. ASHRAE Standard 62.2 provides a formula for determining how much air needs to be replaced, as follows:
Q _fan=0.01A _floor+7.5(N _bedrooms+1)
For example, the continuous ventilation rate for a 3000 square foot, three bedroom house would be:
0.01(3000)+7.5(3+1)=60 cfm
If a fan is run intermittently, the daily fractional on-time (f) and ventilation effectiveness (
) must be considered:
Q _f =Q r/(
f)
If the ventilation system is run at least once every three hours, its ventilation effectiveness (
) is 1.
INTERMITTENT VENTILATION: It was determined that a continuous ventilation rate of 60 cfm was required for the house in the previous example. If the same house uses an intermittent fan that is programmed to run once every hour for 15 minutes, the flow rate is found as:
60/(1.0*0.25)=240 cfm
Various fan controls are known. For example, the Tamarack Airetrak™ microprocessor based control system provides the following features: preset speed—adjustable from 40% to 100% in 5% increments; auto run time—user selectable in 5 minute increments; manual on at full speed—20 minutes; maximum load—180 watts (1.5 amps); _cUL_us; toggle switch hardware; on site programming required; battery backup required; warranty—1 year; no auxiliary control available.
Nevertheless, there exists a need for improved fan controllers.

SUMMARY OF THE INVENTION

An exemplary fan controller for use with a fan such as an inline fan disposed in ductwork is disclosed. The ductwork, for example, may connect ceiling grilles in adjacent but separate bath areas (such as ceiling grilles in a water closet and a master bath area), with the fan operable for example to move hot air and steam to be vented through a roof vent.
With a combination fan control and fan such as an inline fan as disclosed herein, total flexibility is provided to meet ASHRAE Standard 62.2 requirements. The fan control may combine speed control, timing function and high speed override. The fan control may be used with auxiliary control units in different locations, allowing a single fan to provide ventilation of multiple areas.
In some embodiments, the fan control allows a main control and multiple auxiliary controls. This allows a single fan to be controlled from multiple locations. The user settings may be easy to understand slide adjustments, not complex programming operations. Features may not be based on “real time,” thus programming an internal clock is not required. The settings of this control may not be affected by power failures and no battery backup may be required. A cover may be used that increases reliability and safety during customer adjustments. Control may be designed to fit Decora™ style wall plates.
A fan control system includes a main fan controller and at least one auxiliary fan controller. The main fan controller has circuitry for running a fan on a preset cycle, the preset cycle having a preset speed for a preset time. The main fan controller is associated with a first space having a first ventilation port in communication with the fan. The at least one auxiliary fan controller is associated with a second space having a second ventilation port in communication with the fan. Each of the main fan controller and at least one auxiliary fan controller includes circuitry for activating the fan to run on a temporary cycle having a temporary speed for a preset time. Each of the main fan controller and at least one auxiliary fan controller further includes an indicator for displaying activation status of the temporary cycle.
The main fan controller may further includes a fan timer switch which may permit the preset time to be set between 0 and 60 minutes per hour. The main fan controller may further include a fan speed switch which may permit the fan speed to be set between 0 and 100 percent of a maximum preset speed. Each of the main fan controller and at least one auxiliary fan controller may include a touch pad for activating the fan to run on the temporary cycle. Also, the fan may be an inline fan.
Another fan control system may include a main fan controller and at least one auxiliary fan controller. The main fan controller has circuitry including means for operating a fan on a preset cycle, the preset cycle having a preset speed for a preset time. Each of the main fan controller and at least one auxiliary fan controller has circuitry for operating the fan on a temporary cycle having a temporary speed. Each of the main fan controller and at least one auxiliary fan controller further has an indicator for displaying activation status of the temporary cycle.
A ventilation system includes a fan, a main fan controller, and an auxiliary fan controller. The main fan controller has circuitry for operating the fan on a preset cycle, the preset cycle having a preset speed for a preset time. The main fan controller is associated with a first space having a first ventilation port in communication with the fan. The auxiliary fan controller is associated with a second space having a second ventilation port in communication with the fan. Each of the main fan controller and auxiliary fan controller has circuitry for operating the fan on a temporary cycle having a temporary time. Each of the main fan controller and auxiliary fan controller further includes a push button for activating the temporary cycle and an indicator for displaying activation status of the temporary cycle. The main fan controller may further include a slide adjuster for setting the preset speed. Also, the main fan controller may further include a slide adjuster for setting the preset time.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention are disclosed in the accompanying figures, wherein:
FIG. 1 shows a partially exploded, perspective view of an exemplary structure with an inline fan connected to ventilation ports in multiple locations in the structure;
FIG. 2 shows a front perspective view of an exemplary fan controller;
FIG. 3 shows a side perspective view of the speed and time controls of the exemplary fan controller of FIG. 2;
FIG. 4 shows a rear perspective view of wiring connections of the exemplary fan controller of FIG. 2;
FIG. 5 shows exemplary circuitry of the controller of FIG. 2, including AC-DC converter, power to LED, and power to low voltage circuits; and
FIG. 6 shows additional exemplary circuitry of the controller of FIG. 2, including a microprocessor circuit, duty cycle interval set, AC power to fan, programming inputs, a fan boost circuit, fan boost override main and auxiliary, fan reduced voltage control, and fan boost voltage control.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the exemplary embodiment described below involves fan controllers used with an inline fan, it should be understood that the fan controllers instead may be used with other types of fans such as a roof or exterior wall mount fan. Thus, where reference is made herein to an inline fan, the description also applies to other types of fans.
In an exemplary embodiment, fan controllers for a fan such as an inline fan are disposed in multiple locations in a residential setting, as shown for example in FIG. 1. However, it should be noted that the fan controller system described herein may be used in single or multiple level dwellings as well as in commercial settings. Multiple inline fans may be present or alternatively a single inline fan may be used in a single location.
As shown in FIG. 1, a structure 10 has a first room 12, which for example may be a master bath located on a first floor, and includes a first ventilation exhaust port 14 with a main fan controller 16. A second room 18, which for example may be a laundry room also located on the first floor, includes a second ventilation exhaust port 20 with an auxiliary fan controller 22. A third room 24, which for example may be another bathroom located on a floor different from the master bath, includes a third ventilation exhaust port 26 with an auxiliary fan controller 28. Ducting 30 connects ports 14, 20, 26, and the multiport design includes a single inline fan 32 (e.g., a centralized inline whole house fan) that services all of rooms 12, 18, 24. In the exemplary embodiment as shown, the single inline fan 32 is disposed remote from the three rooms, for example in an attic 34, proximate an exhaust region 36 at the roof level of the dwelling. Fan 32 thus facilitates withdrawal of air from each of the three rooms 12, 18, 24, through the ductwork 30, and out the exhaust region 36 at the roof level.
The main fan controller 16 and auxiliary fan controllers 22, 28 may be placed, for example, in areas of the home where specific ventilation rates are required such as in baths, a kitchen, a laundry, or a workshop.
In an alternative embodiment, single or dual inlet fans may be used instead of a centralized inline whole house fan.
Turning to FIG. 2, an exemplary embodiment of a main fan controller 16 is shown. Controller 16 may be used to regulate fan speed and run time for intermittent or continuous ventilation, the settings being user selectable to provide the required amount of ventilation to fit the needs and lifestyle of the homeowners. The controller includes a faceplate 38 with a touch pad region 40 that serves as a contact switch, an LED illumination region 42, fan speed control 44, fan timer control 46, and mounting holes 48 for mounting in a standard single or multiple gang electrical box. Mounting holes 50 also are provided for coupling the fan controller for example to a Decora-style coverplate (not shown). In the exemplary embodiment, the auxiliary fan controller includes the features of the main fan controller 16 such as the faceplate 38, touch pad region 40, LED illumination region 42, and mounting holes 48, 50, but not the fan speed and timer controls 44, 46, respectively, which are only provided with the main fan controller 16. Thus, the fan controller 16 shown in FIG. 2 also represents auxiliary fan controllers 22, 28 as described.
In the exemplary embodiment, a single fan 32 may be controlled from multiple points, for example using the main fan controller 16 and auxiliary fan controllers 22, 28. For example, all of the main fan controller 16 and auxiliary fan controllers 22, 28 are connected such that when a user presses the touch pad 40 on any one of the main and auxiliary fan controller faceplates 38, a blue LED light illuminates on all of the faceplates 38 and the remote-mounted inline exhaust fan 32 may run for example at high speed for 20 minutes (e.g., a high speed boost) or another preset timespan. While the exemplary embodiment includes two auxiliary fan controllers 22, 28, a single auxiliary fan controller or more than two auxiliary fan controllers may be used.
As shown in FIG. 3, intermittent or continuous ventilation may be set by a user. The main fan controller 16 for example includes a timer switch 46 for setting the run-time of fan 32, e.g., 0, 15, 30, 45, or 60 minutes per hour (with the latter of course providing continuous ventilation). In addition, the main fan controller 16 for example also includes an “infinite” speed control switch 44 for adjusting the fan speed from 0 to 100 percent. Again, a high-speed boost cycle, for example running for 20 minutes (or alternatively, for example, 15 minutes) can be activated by pressing the touch pad 40 on the main fan controller 16 or any of the auxiliary fan controllers 22, 28 when extra ventilation is needed. Once the high-speed boost cycle has elapsed, operation of the inline fan 32 returns to the original run-time and speed set on the main fan controller 16. Switches 46, 44 may include slide action actuators, as will be described shortly; advantageously, analog-style duty cycle and speed settings with such switches may be manually operable and thus do not require user or installer “programming.”
In some embodiments, the temporary cycle may be at the same speed as the preset speed. For example, the fan speed may be set to 100% and the duty cycle may be set to 15 minutes. The fan thus may run at full speed for 15 minutes every hour, and also run at full speed for 20 minutes whenever a user pushes a controller's push button/touch pad to activate the boost cycle.
Thus, the exemplary controller(s) are installed for use with a remote mounted fan 32 for venting multiple points. The main fan controller 16 is used to set the number of minutes per hour and the speed at which the fan 32 will run. The same number of minutes per hour will repeat throughout the day. The controller 16 can be set to run the fan continuously at low speed. One or more auxiliary fan controllers 22, 28 may be disposed in other locations. Once installed, pushing the pad 38 on either the main fan controller 16 or one of the auxiliary fan controllers 22, 28 will boost the fan 32 to high speed for a preset time, e.g., 20 minutes. An illuminated region 42 indicates the activation of a boost mode. Such a fan controller helps builders and homeowners meet the ventilation requirement of ASHRAE Standard 62.2.
An exemplary embodiment will next be described, first with respect to hardware with reference to FIGS. 5 and 6.
The main fan controller 16 is powered by 120Vac (60 Hz) and the controller 16 is protected from voltage spikes and surges that may be introduced on the 120Vac inputs. A maximum load of 2.5 amps (from the fan) is accommodated. As shown in FIG. 5, the 120Vac input voltage is converted to +12Vdc using rectifiers, regulators, amplifiers, resistors and capacitors. The +12Vdc is then converted to +5Vdc by two separate voltage regulators. One of the voltage regulators provides power to the LEDs on both the main controller and the auxiliary controller(s). The second voltage regulator provides +5Vdc to the remaining low voltage circuits of the main controller.
Further circuitry is shown in FIG. 6. In particular, a duty cycle circuit contains a user adjustable potentiometer that utilizes a slide action actuator. This allows the user to set the duty cycle from 0 to 60 minutes per hour, in five minute increments although other increments such as 15 minute increments instead may be used in some embodiments. The duty cycle circuit utilizes a RC timing circuit which acts as an input to the microprocessor.
A fan reduced voltage circuit contains a user adjustable potentiometer that utilizes a slide action actuator. This allows the user to set the reduced fan voltage from 30Vac to full voltage. The microprocessor provides a signal to an optotriac to energize this circuit when the duty cycle is in the on state and the fan boost feature has not been engaged. This circuit provides a signal to an AC power to fan circuit which in turn provides power to the fan.
A fan boost voltage circuit provides a signal that drives the AC power to fan circuit at full voltage. The microprocessor provides a signal to an optotriac to energize this circuit whenever the fan boost override has been activated by the user pressing the “boost button” on either the main or auxiliary controllers. This boost feature will run for 20 minutes. The fan boost feature can be deactivated by holding the boost button down for 5 seconds. This high speed override button (e.g., contact-switch/touchpad 40) enables the fan 32 to run at full speed for 20 minutes when needed, for example to vent steam from a bathroom after a shower.
The circuit that provides AC power to fan 32 is a diac/triac circuit that is driven by either the reduced fan voltage circuit or the boost fan voltage circuit.
When momentarily depressed, the push button (touchpad 40) on the main or auxiliary fan controllers completes a circuit that provides an input to the microprocessor to initiate the fan boost override feature and to illuminate the LED(s) on both the main and auxiliary controllers. If the push button (e.g., contact-switch touchpad 40) is depressed and held for 5 seconds the fan boost override feature and the LED(s) are turned off.
A CMOS microprocessor (PIC16F630) controls the functions of the main fan controller 16 and auxiliary fan controllers 22, 28. The microprocessor signals start and stop of fan 32 on both the reduced fan voltage duty cycle and the fan boost override functions. It monitors the status of the push buttons (e.g., contact-switchs/touchpads 40) and the user adjustable duty cycle and reduced fan voltage potentiometers. It also provides a signal to illuminate the LED(s).
A variety of software functions are provided in the exemplary embodiment, as will now be described.
Read Time Potentiometer: The position of the time potentiometer is checked at the start of every hour. This sets the duty cycle of the controller. For example, if the duty cycle is set to 10 minutes, the fan 32 will be energized at the reduced fan voltage for 10 continuous minutes every hour.
Read Motor Potentiometer: The position of the motor potentiometer is continuously checked. This sets the voltage that the fan 32 will run at during the on time of the duty cycle. For example, if the reduced fan voltage is set to 60Vac, the fan 32 will be supplied that voltage during the run portion of the duty cycle.
Check Status of Main and Auxiliary Control Switches: If depressed momentarily, the Fan Boost Override will run for 20 minutes. If depressed for 5 seconds, the Fan Boost Override will be terminated. If depressed at power up then released, LED(s) will flash one time for each 5 minute increment that the duty cycle is set to.
Duty Cycle and Motor Control: At the start of every hour (defined by when the unit was initially powered), the on portion of the duty cycle will initiate if >0. This timing feature requires no battery backup if power is lost. It will simply resume the duty cycle timing once power is restored without losing any of the users' settings.
Drive the LED(s): The status of the Fan Boost Override feature is monitored and the LED(s) are illuminated whenever this feature is active.
The exemplary embodiment of a fan control is designed to be used with a fan 32 for example to meet whole-house ventilation needs. In the exemplary embodiment, the controller enables the fan 32 to run at a preset speed for a preset portion of each hour, 24 hours a day, every day.
Where a single exhaust fan is ducted to draw air from multiple locations, for example up to four auxiliary fan controls may be used with the main fan controller 16. The auxiliary fan controllers may be installed in secondary bathrooms etc., where high speed override is required to meet desired ventilation needs.
For reasons of safety, power should be switched off at the service panel before commencing installation. Also, the main fan controller and auxiliary fan controllers should not be installed where they can be reached from a tub or a shower. Electrical wiring should be done by qualified person(s) in accordance with all applicable codes and standards.
During an exemplary installation, the main fan controller is installed in a standard wall box prewired with line and neutral. Referring for example to FIG. 4, using twist wire connectors, NEUTRAL should be connected to both the white wire 52 (NEUTRAL) on the main fan controller 16 and to the neutral terminal on the remote fan 32. LINE should be connected to the black wire 54 on the main fan controller 16, while the third, LOAD, blue wire 56 on the main fan controller 16 should be connected to the LINE terminal on the remote fan 32. The main fan controller should then be screwed into the wall box so that it is flush with the wall. Power then can be restored at the service panel. By sliding both the time and speed adjusters 46, 44, respectively, to the maximum “on” positions, power to the remote fan 32 can be verified. The time and speed adjusters 46, 44, respectively, then can be adjusted to desired levels and a decorative wall plate (not shown) can be installed. In the exemplary embodiment, the wall plate is removed when making adjustments to time and speed.
In the exemplary embodiment, up to four auxiliary control units, for example, or other numbers of auxiliary control units might be installed in addition to one main control unit. Each auxiliary control unit should be installed in a standard wall box. Two insulated wires are required to connect the main control unit to auxiliary control units. Referring to FIG. 4, the positive screw terminal 58 on the main fan controller 16 is connected to the positive screw terminal on the auxiliary fan controller, and the negative screw terminal 60 on the main fan controller 16 also is connected to the negative screw terminal on the auxiliary fan controller.
In an exemplary embodiment, the controller permits an exhaust fan 32 to start and run once every hour for a preset time interval, which can range from 0 to 60 minutes. For example, if the fan-on time (upper slide adjuster) is set at one quarter from the bottom, the fan will run for 15 minutes every hour at the preset speed (lower slide adjuster). For temporary full speed operation, press the button on the front of the control (main or auxiliary). Fan 32 will run at full speed for 20 minutes and then resume its normal preset cycle. Full speed is indicated by an illuminated region 42 on the front of the control panel. To return to the normal cycle before 20 minutes has elapsed, press and hold the button for five seconds. To disable the controller and fan, press and hold the button for 30 seconds. Note that the controller and fan are not electrically isolated in disable mode. Pressing the button once resumes normal operation.
The exemplary fan controller advantageously may provide the following features: preset speed—infinitely adjustable from 0% to 100%; auto run time (duty cycle)—adjustable in 5 minute increments from 0 minutes to 60 minutes; manual on at full speed—20 minutes; maximum load—2.5 amps; _cCSA_us; Decora™ Styling; easy to use slide switch settings; no need for battery backup; and optional auxiliary controls for additional locations. In some exemplary embodiments, main fan controller 16 accommodates, for example, up to 4 auxiliary fan controllers, or alternatively other numbers of auxiliary fan controllers.
In addition, protective “ski” style coverings may be provided over the potentiometers while still permitting them to function over their entire operating range.
While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein. For example, the main fan controller described herein could also be used to control a ceiling insert fan (typical bath fan).
Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.

Claims

1. A fan control system comprising:

a main fan controller comprising circuitry for running a fan on a preset cycle, the preset cycle comprising a preset speed for a preset time, the main fan controller associated with a first space having a first ventilation port in communication with the fan;

at least one auxiliary fan controller associated with a second space having a second ventilation port in communication with the fan;

wherein each of the main fan controller and at least one auxiliary fan controller comprises circuitry for activating the fan to run on a temporary cycle comprising a temporary speed for a preset time; and

wherein each of the main fan controller and at least one auxiliary fan controller further comprises an indicator for displaying activation status of the temporary cycle.

2. The fan control system of claim 1, wherein the main fan controller further comprises a fan timer switch.

3. The fan control system of claim 2, wherein the fan timer switch permits the preset time to be set between 0 and 60 minutes per hour.

4. The fan control system of claim 1, wherein the main fan controller further comprises a fan speed switch.

5. The fan control system of claim 4, wherein the fan speed switch permits the fan speed to be set between 0 and 100 percent of a maximum preset speed.

6. The fan control system of claim 1, wherein each of the main fan controller and at least one auxiliary fan controller comprises a touch pad for activating the fan to run on the temporary cycle.

7. The fan control system of claim 1, wherein the fan is an inline fan.

8. A fan control system comprising:

a main fan controller comprising circuitry including means for operating a fan on a preset cycle, the preset cycle comprising a preset speed for a preset time;

at least one auxiliary fan controller;

wherein each of the main fan controller and at least one auxiliary fan controller comprises circuitry for operating the fan on a temporary cycle comprising a temporary speed; and

9. The fan control system of claim 8, wherein the main fan controller further comprises a fan timer switch.

10. The fan control system of claim 9, wherein the fan timer switch permits the preset time to be set between 0 and 60 minutes per hour.

11. The fan control system of claim 8, wherein the main fan controller further comprises a fan speed switch.

12. The fan control system of claim 11, wherein the fan speed switch permits the fan speed to be set between 0 and 100 percent of a maximum preset speed.

13. The fan control system of claim 8, wherein each of the main fan controller and at least one auxiliary fan controller comprises a touch pad for activating the fan to run on a temporary cycle.

14. The fan control system of claim 8, wherein the fan is an inline fan.

15. A ventilation system comprising:

a fan;

a main fan controller comprising circuitry for operating the fan on a preset cycle, the preset cycle comprising a preset speed for a preset time, the main fan controller associated with a first space having a first ventilation port in communication with the fan;

an auxiliary fan controller associated with a second space having a second ventilation port in communication with the fan;

wherein each of the main fan controller and auxiliary fan controller comprises circuitry for operating the fan on a temporary cycle comprising a temporary time;

wherein each of the main fan controller and auxiliary fan controller further comprises a push button for activating the temporary cycle; and

wherein each of the main fan controller and auxiliary fan controller further comprises an indicator for displaying activation status of the temporary cycle.

16. The ventilation system of claim 15, wherein the main fan controller further comprises a fan timer switch.

17. The ventilation system of claim 16, wherein the fan timer switch permits the preset time to be set between 0 and 60 minutes per hour.

18. The ventilation system of claim 15, wherein the main fan controller further comprises a fan speed switch.

19. The ventilation system of claim 18, wherein the fan speed switch permits the fan speed to be set between 0 and 100 percent of a maximum preset speed.

20. The ventilation system of claim 15, wherein the push button is a touch pad.

21. The ventilation system of claim 15, wherein the main fan controller further comprises a slide adjuster for setting the preset speed.

22. The ventilation system of claim 15, wherein the main fan controller further comprises a slide adjuster for setting the preset time.