• Operating a properly sized, 2-ton air conditioner with a seasonal energy efficiency ratio (SEER) of 10 in Atlanta, Georgia, costs over $250 per cooling season (1,250 hours) based on 8.5 /kwh or roughly 20 per hour of runtime.

• A large, 18,000 Btu/hour window unit air conditioner with an energy efficiency ratio (EER) of 8.8 costs more than 17 to operate for one hour.

• By contrast, an HV 1000 whole house fan draws only 115 watts and costs less than 1 per hour of use.

Your fan has door on it what is that used for? When not in use the fan forms an insulated air tight seal between your attic and living area.  Other whole house fans on the market afford fans with no ventilation.  In the wintertime, large amounts  of heat will be lost to these holes in your ceiling, which in turn waste energy and increase heating costs.   

What are minimum roof venting requirements for the HV1000/HV1600?
The HV1000 requires at least 1.33 sq. ft of unobstructed roof venting, or net free area (NFA).  This is calculated based on 1 sq. ft of unobstructed roof venting for every 1000 cfm.  Generally for every 750 cfm = 1 sq. ft nfa.

 The HV1600 requires at least 3 sq. ft of unobstructed roof venting, or net free area (NFA).  This is calculated based on 1 sq. ft of unobstructed roof venting for every 1000 cfm.  Generally for every 750 cfm = 1 sq. ft nfa.

If your home has vents that are 12 x 12 (one square foot) in overall size, you would not actually be getting one square foot of ventilation area. The framework of the vent and especially the insect screening in it reduces the overall amount of area that the air can actually pass through -- sometimes by as much as half.

For that reason, all types of attic vents, are rated in net free area (NFA), which is the actual amount of open ventilation area that the vent contains after deducting out all of the space taken up by the frame and the screening

Can We Recommend a installer in your local area? Unfortunately, in this aspect, we are limited to our local area - which is Los Angeles, San Fernando Valley and the Santa Clarita Valley area of Southern California.  We Cannot RECOMMEND an installer in any other area.

What is a typical price of installation for the unit?  Costs vary from region to region, pricing can range anywhere from $150 up to $500.  A lot has to do with home configuration, attic access, power access in attic, etc.

The HV1000 Mechanical Doors Are Motorized - Pulling them manually will break the unit - and it will need to go back to the factory for repair!

The HV1000 wiring requires a constant hot (so the door motors may operate) - If you wire the unit improperly, it will not work! 

Again, the doors on the unit are motorized, they need a certain amount of clearance in order to to open/close - 1.75" from the outer base of the unit and 11" from the top of the unit - installing the unit to close to permanent objects will cause the doors to impact against the object and damage the unit.

Can the HV use a different switch?  Yes.

Can the HV100 be wired to a standard line cord?
No The HV1000 MUST BE HARD WIRED and SHOULD NEVER BE USED WITH A STANDARD LINE CORD.

General Questions:

1.  What is whole house cooling?  Whole house cooling is a method of cooling homes that takes advantage of the natural temperature differential that often exists between indoors and outdoors.  Whole house cooling is accomplished by pushing heated air out of the home through the attic and drawing in cooler outside air.  By moving cooler air through the home at a moderate rate, heat is removed.

2.  Is whole house cooling like air conditioning?  Not exactly. Whole house cooling will reduce the temperature inside the house to the outdoor temperature, but not below.

3.  When do I use whole house cooling?  Any time the outdoor temperature is lower than the indoor temperature.  Simply open a window and turn the equipment on.  The open window will supply cooler air to replace the hot air that the equipment is exhausting.

4.  Why must I open a window? In order to bring cooler air in, it must be drawn in from the outside.  If you run the equipment without a window open, you run the risk of creating negative pressure in the house which can cause dangerous fumes back drafting from your gas appliances; such as a stove, clothes dryer or hot water heater.

5.  Can I use air conditioning and whole house cooling?  Yes, but not at the same time.  Use the whole house cooler to reduce the internal temperature then run the air conditioning unit.  Use of a whole house cooler prior to air conditioning can Significantly Reduce your A/C costs.

6.  Are there drawbacks to whole house cooling?  Traditional whole house cooling equipment is noisy, difficult to install, and requires maintenance.  It also "short circuits" your attic insulation, reducing the energy efficiency of your home.  Traditional systems are power hungry and detract from the appearance and comfort of your home.  All these drawbacks are eliminated by the revolutionary.

Is a fan with 1000 or 1600 cubic feet per minute of air flow adequate ventilation?  Traditional whole house fan guidelines require 1.5 to 2 times the sq. footage of air flow for whole house cooling. 

Not only does this require in some cases a large amount of attic/roof venting to allow the air flow to escape.  Failure to have adequate venting in place will cause the air attempting to exhaust out of the home to find the path of least resistance, down wall and out through electrical boxes, back into your home! 

Tamarack engineers believe that users get the most benefit with the first air exchange that occurs in your home.  The HV will do an air exchange in most homes in a matter of minutes. 

 The "breeze" effect that larger whole house fans generate are what people like about the bigger whole house fans.  Stored heat takes time to dissipate from your home, it permeates in the attic, walls, carpeting and even your furniture!  Because of the noise factor, people tend to turn off the larger whole house fans much sooner than needed.  The HV1000 is much quieter and can therefore run for longer periods of time, all night if needed - and it uses only 116 watts of power.  It is suggested for users of the HV1000 who wish to feel the "breeze effect" they supplement the air flow with ceiling fans and/or standard room fans. 

Will the fan cool my house?

There are many variables that will determine how quickly a whole house cooler can cool a home; the size of the home, inside and outside temperatures, attic area etc.  The fan will change all the air in a 1,500 square foot house in 15 minutes.  For homes larger than 2500 sq. ft, multiple units are suggested, but not required. 

Questions about the HV Unit:

How is this fan so revolutionary?
In about every possible way!  The fan is quiet, simple to install, energy efficient, has a built in insulating system, requires no maintenance and has a small, discreet grille. 

How quiet is quiet?

A little louder than a range vent over the stove, or a bathroom ventilation fan.  When compared to a traditional whole house fan, well there is no comparison...

The fan is rated at 3 sones.  What is a sone?  A measurement of sound output, Sones translate decibel readings into numbers that correspond to the way people sense loudness.  Sones follow a linear scale, like inches.  Double the sones is double the loudness.  In contrast decibels follow a "logarithmic" scale which is a multiplying of numbers instead of adding. 

Technically speaking, the some is equal in loudness to a pure 1,000 cycles per second at tone at 40 decibels above the listener's threshold of hearing.  8 Sones would be the equivalent to a busy freeway, 3.0-4.0 sones a  TV/Radio, 2.0 sones a calm office. 

 
Where do I install the whole house fan?

The fan should be placed on the framing between the space to be cooled and the attic.  In most cases that means the attic floor, but the fan can also be mounted vertically to cool cathedral or vaulted spaces.  Locate the system as close to the center of the home as possible for an even draw throughout the home.

How efficient is the fan?

The HV1000 fan uses 116 watts of power while the fans are running, 6 watts when the insulated motorized doors are opening or closing, and 0 watts when turned off.  The doors are insulated to R-22 to minimize conductive heat loss or gain when the fans are not operating.  Both doors are fully gasketed, like a refrigerator, to ensure a tight seal.

No maintenance at all?

That is correct!  The fans are sealed and permanently lubricated.

How does it look from inside my home?

The grille for the fan is a low profile, slotted grille, similar to an air conditioning grille.

What else do I have to buy?

All you will need is wire to install the fan and an electrical box for the switch.  Several pieces of framing to box the unit - and a can of paint to match your ceiling (painting the inside of the attic frame is recommended.  The fan comes with a lighted on/off switch, weather stripping to seal where the fan meets the frame, a grille and all mounting hardware.

What is the warranty for the unit?

Three years, parts and labor on manufacturer defects.

Other FAQ's:

What is the rough opening of the unit?   14.5" x 22.5"

Clearance needed when doors are open? 11" from base of unit up.

Watts Used? 116

Can it be installed with a timer? Yes.

Can this unit be mounted vertically? Yes.

Should I be concerned about Heat Loss Due To An Uninsulated Whole House Fan ?  The bottom line is that you will pay more to heat your home due to loss of insulation.  The way that is calculated is listed below (somewhat technical):

Effective "R" Values

An insulation system is rated by its overall "effective" value, the average of its weakest and strongest points. This is the "effective" R value. Voids or under-insulated areas in the insulation blanket drastically reduce the effectiveness of the insulation system.

The following is a comparison between an uninsulated, 36" whole house fan and Tamarack Technologies, Inc. HV 1000 installed in a 1008 square foot attic floor, insulated to R-49 (per DOE insulation fact sheet for electric heat).

Where:

R_eff = Effective R value

U₁ = Conductance of material 1

Area₁ = Area in square feet of material 1

U₂ = Conductance of material 2

Area₂ = Area in square feet of material 2

The installation of a traditional whole house fan carries a huge energy penalty when the homeowner fails to cover the fan. Anecdotal evidence suggest that the American homeowner will forget or neglect system maintenance - covering and uncovering the fan. The only way to ensure that the attic air sealing and insulation is not compromised is to have a well insulated, automatic cover. 

Conductive Heat Loss

In terms of heat loss, reducing the effective R-value of the attic floor from R-49 to R-15 would have a dramatic effect.

Where:

H = heat loss in BTU's per unit of time

A = area of section in square feet

DD = number of heating degree days at the site (about 7000 for Madison, Wisconsin)

R = Effective R value of section

1. The attic alone with no penetrations:

   H = 24 x 1008 x 7000 = 3,456,000 Btu's

                    49

    

2. A traditional, uninsulated 36" fan:

   H = 24 x 9 x 7000 = 7,560,000 Btu's

                  .2

   (Attic with 36" fan installed total: 10,985,000 Btu's)

    

3. An HV 1000:

    H = 24 x 2.66 x 7000 = 20,312 Btu's

                              22

   (Attic with HV 1000 installed total: 3,466,880 Btu's)

These numbers indicate decisively the enormous penalty that an uninsulated 36" fan can create (increasing Btu loss by over 215%). The same attic with an HV 1000 installed reflects a less than 1% difference from an attic floor with no penetration.

 Convective losses

The convective losses through an uncovered fan are very high. Despite the fact that the average whole house fan has a louvered cover, the number of edges to the louvers makes the total "crack" length very high. The louvers are certainly better than an open hole, but with wind pressure and the stack effect, the louvers rattle and are often lifted even when the fan is not running. At an extreme (eighty degree) temperature differential (70F inside and -10F outside) there would be about 600 pounds of lift exerted on the ceiling of a 1000 square foot house just from the stack effect.

Seasonal convective loss = 24 x c x Q x L x DD

Where c = .018 (the heat capacity of air)

Q is a constant based on the width of the crack est. 3/32"

L = length of crack in feet

DD = Degree day year

A. Convective loss through a 36" uninsulated whole house fan with gravity louvers: 12 slats x 3 feet wide

24 x .018 x 27 x 36 x 7000 = 2,939,328 BTU's

B. HV 1000 convective loss: the measured leakage through the HV 1000 in a situation when the house is under positive pressure of 5 pascals relative to the attic, is 10 cfm.

24 x .018 x 10 x 7000 = 30,240 BTU's

Cost

What does all this mean in terms of cost?

* 85% efficiency

All amounts rounded to the nearest whole cent. Fuel costs differ by region and time. It is likely that fuel costs are higher, but locating the house in a 7000 degree day climate is a very cold climate, and a 1008 square foot house is small.

It is clear that a whole house fan should be covered when it is not being used. There is almost a 300% increase in heating cost with an uncovered 36" fan. The HV 1000, however, adds an insignificant amount to the annual heating load.