Fan-On Energy Savings

How the “Fan-On” position can actually save money.

Energy efficiency is an interesting term. Often people associate it with simply using less electricity, but really it’s not about that at all. It’s about effectively converting energy into work. Sacrificing the amount of work performed to save energy is not greater efficiency.

For example, I once lived in an apartment that had an in unit washer and dryer. The dryer was a new “high efficiency” model that claimed to dry your clothes using nearly half the electricity of a standard dryer. Sounds great at first, the problem was that it was only about half the size of a standard dryer and said right on it that it could only handle a half load meaning you would have to run it twice to do a full load. Also it didn’t even do a half load very well. We would often have to run it 2 or even 3 times to get our clothes mostly dry (this was in central Florida so clothes were never fully dry anyway). We and many of the other tenants of the complex complained about the poor quality of these new dryers. The owners said that they would save us money in the long run and we would be grateful for them even if it took a little longer to dry our clothes. But they did not save us money, in fact most saw increased bills. We stopped using ours completely and either went to the Laundromat down the street or attempted to hang dry our clothes (does not work well in central Florida). In the end I learned that using less electricity is not the same thing as increased efficiency.

Sadly In the HVAC industry I see the same problems. Many are so focused on energy savings they forget about comfort. The problem is when people are uncomfortable they are going to adjust the thermostat to whatever is required, for them to be comfortable. At this point the so called “energy savings” disappear.

Here at FanHandler we have found a way to create real energy savings and truly reduce electric bills by making people more comfortable, not less. We have found that these energy savings come from an unlikely place. Ladies and gentlemen, I introduce you to the “Fan On” position.

For years, many have known about the comfort and indoor air quality improvements that come with the constant air circulation of the fan on position. The main problem is that it causes what engineers call a “parasitic use of electricity”. Engineers have concluded that when it comes to using your furnace in the fan on position, the costs outweigh the benefits for most of the population. As a matter of fact there are countless articles written on why you should not use this forbidden “Fan On” position and a lot of math showing just how much electricity and money you are throwing away if you do. And they are right. I am not here to disprove or dispute their findings. However, here at FanHandler we believe that constant air circulation can be done right, and actually save more money than using your system in “Auto”.

You see there is something known as the “fan laws” that has helped us to find the solution.

The fan laws state that if you decrease the speed of the fan by ½ you decrease its energy usage to 1/8. This is pretty well known throughout the industry and many systems are now decreasing the speed the fan speed to 800 or 600 rpm when in the fan on position in an effort to reduce the electricity consumed by the constant blower. This gives significant savings over using the fan at full speed, and has the added benefit of reducing the noise of the constant blower and even making the air filters work slightly better because they are not blasting the germs and dust particles right though the filters. This is a good improvement but, it’s still considered by many to be a waste of electricity. And to some degree they are right. You will not save electricity by running the fan constantly even at 600 rpm. However here at FanHandler we have found that if you continue reducing the speed of the fan there is a switching point where the improved comfort brought by the continuous fan actually outweighs the cost of running the fan.

The Department of Energy's Energy Savers website says that homeowners typically save 3% on their heating bill for every degree that they turn down the thermostat during the winter. In other words this tells us that comfort is a factor in the energy efficiency equation. After all making people comfortable is what furnaces were designed to do in the first place. If we as HVAC professionals can make the home comfortable enough that homeowners don’t need to have the thermostat set as high in the winter, or as low in the summer, then we are saving the home owner money and truly making the whole system more energy efficient.

Constant air circulation has proven to make homes more comfortable. It does this by eliminating the hot and cold spots in homes and keeps an even temperature from room to room and even more importantly, from floor to ceiling. When we put the “comfort factor” in to our calculations, that is the 3% energy saving per degree, it’s easy to see that in real world conditions, constant fan can save a significant amount of energy.

Here at FanHandler we have done real world testing not just laboratory testing to determine that the sweet spot for the fan speed is about 300 RPM. At 300 rpm you are now using only about 1/60th the amount of electricity. With high efficiency ECM blower motors, that's only about 12 to 15 watts. That’s one forth the power consumed by a standard light bulb. We have found that at this speed there are many benefits. Including:

  • Completely silent operation (Even standing right outside the air handler you cannot hear that the fan is running).
  • Vastly improved air quality(especially for things like UV lights and electronic air cleaners)
  • Increased motor life(when the fan never shuts off it’s see significantly less ware from the usual banning on and off).
  • And of course energy savings.

Now here is the part you have all been waiting for. The Math(okay so maybe just us engineers have been waiting for this, but here it is anyway).

According to EIA In 2018 the average cost of electricity in the US was around 13 cents per Kilowatt hour. In other words if you were to use 1000 watts for one hour it would cost you 13 cents. So at 15 watts continuous use for a month you would use a total of

15 Watts x 24 Hours x 30 Days = 10800 watts or 10.8 kilowatts costing a total of $1.40 cents.

Now, during the colder months your furnace runs about 30% of the time anyway. So you reduce that figure by 30% giving you an increase on your electric bill of $0.98. That’s less than a dollar a month for using the fan on position at 300rpm.

Now as we have seen from studies and from the reports of our own customers. With continuous air circulation homeowners are just as comfortable at a thermostat setting 3 degrees lower then it was during intermittent operation. Remember there is a savings of 3% per degree so at 3 degrees that is 9% savings on average. The heating bill for a typical home in the US is $200 per month during the heating season. 9% of $200 is $18.00. Minus the $0.98 you have a total savings of $17.02 just for using continuous air circulation.

In addition to that if you factor in higher efficiently of an ECM blower motor during a heating or cooling cycle, and ECM Modulator kit can save a significant mount over a standard PSC setup.

And there you have it. When constant air circulation is done correctly the “Fan On” position can actually use less electricity than “Auto”. And as we have found, in most cases it does.

Noise Reduction

Vivian noise 4 web
Noisy Furnace Waking up the Baby?
One of the most common complaints homeowners have with their central air system is noise. That sudden blast of air that wakes them up at night, or causes them to reach for the remote to turn up the volume on the TV. Most people believe there is nothing they can do about it so they just learn to live with it. However there is an answer to this all too common problem.
With a FanHandler installed, your system will quietly ramp up the fan speed, eliminating that loud whoosh of air and the slap of the air filter that you have become far too accustom to hearing. Many home owners have told us that this feature alone has made insalling the FanHandler worth while.
And, if you choose to upgrade your system with one of our HVAC whisperer packages. Your system will also get a complete motor upgrade to an ultra quiet high efficiency Nidec ECM. These motors are the smoothest, and quietest motors available. You will be amazed at the difference!

Indoor Air Quality

How FanHandler can improve the air you breathe.

We spend 87% of our time indoors, so it’s no surprise that indoor air quality can have a big impact on our health.

Here are 4 ways FanHandler systems improve indoor air quality.



1. Continuous Air filtration 

FanHandler systems continuously circulate the air in your home to keep your filters working 24/7/365.



Gentle fan speedAsset 14x2. Gentle Fan Speed Changes

When it’s time for heating or cooling, FanHandler systems will gently, quietly increase the fan speed, to eliminate the sudden burst of air that can blow dirt and dust right though filters, and into your lungs!



lower HumidityAsset 14x3. Humidity Control

FanHandler systems are among the most efficient humidity controllers on the market today. If you live in a humid environment, you know how much of a problem it can be for your health. Controlling the humidity is crucial to eliminating the hazardous molds, which can build up in your forced air system. In addition, having the proper levels of humidity vastly improves comfort.



UV Light and Air Cleaner

4. UV Lights and Electronic Air Cleaners

FanHandler systems use a reduced air flow during the periods of the day when there is no call for heating or cooling. This allows UV lights and electronic air cleaners the exposure time they need to kill harmful bacteria, enabling these and other purification devices to work at their peak efficiencies.





You may be thinking, this all sounds great, but won’t running the fan continuously be expensive and noisy?

energy cost graph webThis may be true of traditional CAC systems however FanHandler systems bring the fan speed down to around 300 rpm for a gentle and silent air flow. This is half the speed of any other continuous air system. This highly reduced speed has the benefit of further increasing comfort and drastically reducing the energy consumed by the fan motor. In fact, FanHandler is over 60 times more efficient than traditional systems and nearly 8 times more efficient than our closest competitors! FanHandler systems are so efficient they can circulate the air in your home for an entire month for less than 1 dollar worth of electricity, while a standard system may consume nearly 60 dollars worth in the Fan-On position.

Thousands of homes across America are already experiencing the superior comfort, air quality, and efficiency that FanHandler systems provide. So what are you waiting for, contact your local HVAC professional to get a quote on upgrading your system today.

FanHandler How Comfort Gets Done.

Zoned Systems (Eliminate the bypass damper!)

ecModulator 600x132 shadows


ECM MODULATOR 4Z for Zoned systems


The ECM Modulator 4Z measures and maintains the duct static pressure in a zoned system. As some zones close down and the system pressure starts to build, the ECM Modulator 4Z imediately senses this and reduces the blower’s speed so that the systems pressure stays at your set point. Thus the proper air movement from the open zones is maintained. During the times when there is no call for heat or cooling, and constant fan is desired, the ECM Modulator can be set to drop to any slow speed that you choose. In this way, all IAQ products will remain operating and at the highest possible efficiency.



Installation and wiring must comply with all local and national electrical codes.

Only qualified HVAC/IAQ technicians and service mechanics may install the ECM modulator control. To do otherwise will void all warranties.




Zone pressure web

Temperature  sensor

YellowSensorPlace this

in the

delivered air



Pressure pick up plate and tubing.


Place this

Before any

Zone dampers

or registers.


Connect pressure tube to control


After the Installation is complete. It is now time to set the desired duct pressure. Usually the smallest zone is of the greatest concern. The ECM Modulator 4Z is calibrated at the factory to hold about .3 inches of water column. Try closing all the dampers except for the one(s) controlling the smallest zone, if it is noisy and you want to reduce the pressure. Keep in mind that the duct pressure that you set for the smallest zone is the same pressure that the ECM Modulator 4Z will try to maintain when all dampers are open.

Setting Your Maximum Duct Pressure

On the ecMModulator 4Z controls the HI SET pot is used to adjust the pressure limit. Turning the pot clockwise will increase the maximum duct pressure and counter clockwise will decrease the maximum duct pressure. 2 full turns will approximately equal 0.1" wc. ecMModulator 4 Z controls are shipped with a factory duct pressure setting of about 0.3” wc. Before you begin setting the pressure re-move the temperature sensor wire from the control (top terminal). This will drive the blower up to and slightly past the present pressure setting speed. Wait while the blower’s speed settles before changing the pressure setting. If you want to control from pressure alone, then just remove the temperature sensor and leave it off. A step by step procedure for adjusting the pressure is listed below.

  1. Re-move the temperature sensor wire from the control to cause the motor to go full speed.
  2. For a higher pressure, turn the screw on the HI SET pot clockwise.
  3. For a lower pressure, turn the screw on the HI SET pot counterclockwise.
    • If the pressure is close to what you want, turn the pot slowly about a quarter turn at a time to give the motor and control time to adjust. A rough calculation is that about two turns will change the pressure about 0.1” wc.
  4. When you are at or above the programmed pressure setting, the ZO light will be on.
    • If you overshoot the adjustment and wish to reverse the setting you made, you can figure that it takes about 1/4 turn to take up the slack in the pot’s clutch before you will notice a change.

Once you achieve the pressure setting you want, reconnect the sensor wire.



NOTE: The ECM Modulator is not a safety or limit control. It does not eliminate the need for a low temperature or pressure cut out and a high temperature limit control. To leave these out of any zoned system is poor design and improper practice.



The purpose of this article is to list some of the common problems encountered with humidity control in modern high-speed air conditioning. It will explain how controlling blower speed from a temperature signal will eliminate these common problems as well as increase the comfort and livability of.a home.

In the quest for energy efficient operation, the residential HVAC industry has adopted practices that are based on opinion rather than fact. The consequences of some of these practices have resulted in major discomforts for the homeowner. Most homeowners will adopt measures to circumvent these discomforts. An example of this is that the homeowner will reduce air conditioning thermostat settings by about three degrees to get away from that muggy feeling. This requires about an additional 18% in energy consumed by the air conditioner. So, what looked good to energy geeks who don’t get out of the lab and don’t have a clue as to the overall function of an HVAC system, has been eaten-up by the homeowner’s real-world desire for comfort. .


  1. If water stands in a drain pan, the pan is either poorly designed or improperly installed.
  2. What is normally called “low load conditions” refers to load from temperature gain and is not necessarily the total load necessary for efficient operation and comfort.
  3. Humidity can be a significant load that is not addressed.
  4. Every 10% drop in relative humidity is the comfort equivalent of a 3° drop in temperature. I.e. drop the humidity by 10% and you can enjoy the same level of comfort at a three-degree higher thermostat setting. This saves energy.
  5. Water adheres to the A/C coil better as the coil gets colder.
  6. When the A/C compressor turns off and the blower’s speed remains high, the coil gets warm very quickly and doesn’t grip the water as tightly.
  7. The faster that air moves over an A/C coil, the higher the coil’s bypass factor, the warmer the coil, the warmer the delivered air temperature and the less adhesion to water.
  8. A warm coil (either right after the compressor shuts off or under high air velocity) doesn’t hold water tight enough to give it time to flow down the entire height of the coil to the drain pan before being blown from the coil by the high-speed air movement through the coil.
  9. If (with the compressor running) the air velocity over the coil is less than 500 feet per minute: An A/C coil, under normal operating conditions, will hold water long enough for it to flow down the coil and into the drain pan.
  10. The method of determining the air velocity (called face velocity) over the coil is to divide the CFM air delivery from the blower by the square foot face area of the coil. When velocities reach over 600 feet per minute, then water will definitely strip from the coil and down the ducts even if the coil is quite cold.
    1. The space between the coil plates or fins (Usually 14 fins per inch) is designed to allow air to move freely through the coil and still allow enough air to impact the coil to reduce the temperature of the air enough for effective cooling and humidity removal.
    2. The thickness of the coil. Usually allows 3 or 4 rows of tubing.
    3. Water that is flowing down the coil takes up space. There is a condition where the amount of water in the coil can build up because it can’t get down to the drain pan fast enough, this excess water takes up free space and reduces the amount of free area for air to flow at an efficient (500 ft. per minute) velocity through the coil. It has the same effect as reducing the size of the coil. In this case, the air velocity through the remaining, or available, free area increases to over 600 feet per minute. At that point water is stripped from the coil.
  12. Coil bypass factor is the percentage of air that goes through a coil without being affected by the coil. Cooling is done only to the air that actually touches the coil’s fins.
  13. Typical bypass factors for a three-row coil with 14 fins per inch are:

















The delivered air temperature is the result of mixing very cold air cooled by the coil fins and the room temperature air that goes through the coil space without being cooled.


Blower speed timed programs:  i.e. run the fan for a number of minutes (maybe 7 minutes) on low (about ½ speed) During this time the coil is super cold and super efficient and collects large amounts of water. During certain high humidity conditions, the A/C coil loads up with water faster than it will drain. After the low speed segment has timed-out, the blower ramps to high speed. This does two things: First it warms the coil, which reduces the water’s adhesion to the coil. Second, high velocity through the remaining free space breaks the surface tension of the water so the droplets break apart and they blow off the overloaded coil and down the ducts. This is why many contractors in high humidity areas do not use this feature.



In high humidity areas, it is also common to either run the fan on intermittent or turn off the fan for a period of time after the compressor shuts down in an attempt to give the coil time to drain. This is not a solution to the recognized problem of blowing water off the coil and re-evaporation. It is avoiding the problem rather than solving the problem. It also makes the home less comfortable, less quiet and the wide variety of indoor air quality products less efficient.


The common statement concerning coil drain pans is: “When you run the blower while the compressor is off, you’ll re-evaporate the water standing in the drain pan.” Somehow this statement has been used to the point that it has become folklore. The proper design and tilt of the drain pan is all that is required for it’s proper function. First, the word drain in the name of the device should provide a clue to its function. Water should not be standing in a drain pan. Second, to evaporate a couple of ounces of water at temperatures we are dealing with is not instantaneous. Third, even if a few ounces of water were evaporated into the thousands of cubic feet of air that are inside a home, it would have about a zero consequence.





  1. Blower speed can be controlled effectively and efficiently by changing the voltage to any high quality shaded pole or PSC blower motor. It has been done since the late 1950’s.
  2. When blower speeds are controlled through quality motors, the fan laws are in full effect.
    1. When you reduce the speed of the blower by 50%, you reduce the CFM by 50%
    2. When you reduce the speed of the blower by 50%, you reduce the static pressure to one fourth.
    3. When you reduce the speed of the blower by 50%, you reduce the power required to one eighth of that required to run it at full speed. (i.e. You can run a good blower motor for eight hours at half speed for the same amount of money that it would take to run it full speed for one hour)
  3. Typical speed/temperature relationships for blower speeds controlled by temperature. Using a typical, average designd for a three-ton system. (Using rounded numbers for simplicity)
    1. 36,000 BTUH
    2. 400 CFM per ton or 1,200 CFM at full speed
    3. Minimum speed is set at about 35 or 40% of full speed or about 450 CFM at about 450 rpm blower speed when the delivered air temperature coming off the coil is above 68° F.
    4. Maximum blower speed about 1070 RPM when the delivered air temperature coming off the coil is about 50° F.
    5. The fan is set to run continuously.
    6. For every degree of temperature reduction from 68° F delivered air the fan motor’s speed increases about 34 RPM. Or for every 34th of a degree temperature drop, the fan speed increases one RPM. This is smooth and seamless.




  1. Room temperature about 75°.
  2. Indoor humidity high. (maybe over 70%)
  3. Blower running continuous at about 450 RPM and delivering about 450 CFM.
  4. Compressor comes on.
  5. Air is moving over the coil slowly.
  6. The bypass factor is about 10%, which means the coil is super efficient and very cold.
  7. Because the coil is very cold and super efficient, it cuts into the latent load and begins rapidly collecting water.
  8. Because the coil is so cold, the air coming across the coil also cools down rapidly and reduces the delivered air temperature.
  9. Because the air temperature is reduced, the blower’s speed is automatically and instantly increased.
  10. Here are some interesting points: The coil has established its grip on the latent load and is collecting water to the coil’s maximum design capability to capture water.
  11. The compressor doesn’t know the difference between latent and sensible loads. It only sees a load.
  12.  Because the coil is capturing water to it’s maximum ability, the remaining capacity of the compressor is then devoted to the sensible load. The remaining compressor capacity may not be enough to drive delivered air temperature down to the 50° temperature required for full speed blower operation. The delivered air temperature might be 54° degrees and between 900 and 1,000 CFM. (That is why when Florida, gulf coast and contractors in other high humidity areas first install temperature controlled blower modulating controls, they think that the blower is going too slow. However, when they look at their gauges, they see the unit is working its lungs out because it is concentrating on the latent load. A day or two later, the house has dried out. The delivered air temperature is colder and the blower is running faster.)
  13.  Compressor Shuts off:
  14.  The coil and delivered air begin to warm a little. The blower’s speed immediately and smoothly drops to about 50% of the way between the highest speed that it achieved at its coldest point and the 450 CFM minimum speed. Lets say about 675 CFM.
  15.  675 CFM isn’t going to blow water off a 1,200 CFM coil. The coils is going to drain.
  16. Interesting point #2: There is a good amount of cooling capacity in pressure equalization. The high-pressure liquid refrigerant moves into the evaporator and does some cooling. It usually takes about 5 to 10 minutes for the pressure in a system, with good valves, to equalize.
  17.  During this time, the blower’s speed is smoothly dropping towards the minimum speed. The coil is cool, the coil is draining, and there is no re-evaporation.


Temperature controlled blower speed:

  1. Eliminates or greatly reduces the problem of blowing water off A/C coils.
  2. Results in maximum humidity removal by automatically adjusting for latent loads.
  3. Allows comfortable and quiet continuous blower operation that permits all accessories attached to an HVAC system to operate at full-time at full efficiency.
  4. Increases efficiency.

Dick Peters, P.E./CM


FanHandler Inc.         


  • I love my Fan Handlers, unfortunately the building came with a couple that are for gas heat and I am all water sourced heat pump.  I need a quote  for two heat pump fan handlers.  Thanks for the best solution to air movement!


    John Jackson
    J Cubed Services (also RSI)
    5426 Guadalupe Street
    Austin TX 78751