Just found this thread addressing the use of Panasonic's Whisper Green with a ductless heat pump.  No distribution system other than the Whisper Green moving air between rooms.


Curious about your thoughts. 

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Yes, these multispeed fans have two dials behind the grille on the face of the fan.  One controls the low speed and the other controls how long the fan stays on high speed before defaulting back to the original low speed.  The dials look like this:

Generally, these fans are used to provide both local spot ventilation in a bathroom and whole building ventilation to meet ASHRAE 62,2.  The low speed can be chosen to meet the whole building continuous rate, say 50 cfm for a 2000 square foot three bedroom house (7.5 cfm x (# of bedrooms + 1) + (2000 square feet x 0.01 cfm/sf).  When the control switch on the wall is closed, the fan switches to the full high speed of 130 cfm  as long as the switch is on, plus the number of minutes set on the timer to the left.  Then it drops back down to the low speed cfm set to meet the whole building ventilation rate.  Your homeowner would want the VKS3 model that uses an unpowered switch to control that boost, not the VKM3 version that uses a motion sensor to control that boost to full speed.   There are also similar fans rated at 80 cfm for the high speed that can be set for 30, 40, 50, 60, or 70 cfm with a boost to 80 cfm, but I would recommend the 130 cfm model to move more tempered air.  It is still rated at less than 0.3 sone at 130 cfm while using less than 12 watts.


For this application, I would use two switches, one for power to control the on-off  of the fan wired to the black and white wires and a non-powered control switch for the two red control wires to kick the fan to 130 cfm.  Then the homeowner can adjust the speed at the fan behind the grille for the low speed and just turn it on and off as needed for distribution of the heated or cooled air.  If he wants the full speed, he can then close the control switch and leave it on high.  He is not looking for whole building ventilation but rather redistribution of the heated or cooled air from upstairs.  He can experiment on what airflow rate he finds most comfortable and effective.


The fan is designed to be installed as a ceiling insert fan and that is the best application.  The UL listing requires that the fan has to be at least 7 feet above the floor to avoid anyone pushing a finger through the grille and hitting the blower wheel, especially kids.  If that can be met and the discharge pointed down, the only issues are that the damper will not close (I would just remove it for this application) and the motor will experience slightly different stresses on the bearings that may shorten its life somewhat, although we have never had any issues come up.  These DC motors are intended to last 10-20 years of continuous use, so this is not a big concern.



Thanks Don! 

Very helpful info.  I think this will work. Bottom of the grill will be over 8 ft  from the floor. Two switches make sense.  I agree, we should go with the 130 CFM fan rather than the 80 CFM fan one.  The delta T is pretty small, so it makes sense have that extra capacity and flexibility.



We have a similar situation in York, Nebraska ... A little different but the story is cool.     It's a second story apartment with a distant bedroom that needed conditioning.   The performance was so bad before the project that the tenant moved out, never being comfortable.   We installed the same unit you have in the main room and a Panasonic bath fan powering a buried duct to that far bedroom. (Along with the rest of the sealing and insulation package)   The performance was so improved that the tenant begged to move back in, and they did.    We chose very simple controls.   A line voltage thermostat.  


Linda, Don,

I love the concept of moving air around for 12 watts with a Panasonic bath fan.    As you know, I have been experimenting with the ducted method of using the small MSHP's    I've determined that it is less efficient (if you want absolute minimum energy usage) ... but it can provide very uniform room to room temps, if that is the major objective.   I have two projects now being monitored by DOE and NREL from which I presented preliminary data at Pittsburg ACI, and mountains more will be coming.    This system also helps distribute the single point Panasonic ERV which is located near the return.    It is keeping temperatures very stable, even with the bedroom doors closed, with the Tamarack under door return air paths.  

     This system answers the perceived American need for forced air to every room and after a proper design and install is pretty bullet proof   (occupant proof)

     I'm convinced that using the single point delivery systems and moving the air with fans as we are discussing is more efficient.   (9 points higher SEER to start with, plus 1/3 the fan watts, just to start with)    So I'll be putting in this type of system in future houses that aren't being used for testing.    The single point delivery with fans is more for energy geeks who like to control and fine tune their systems.    (that would be me,  ... and I think you)

     Final thought on distribution with Panasonic bath fans.    I have two installed in my house and they are situated where they can push the heat from the pellet stove in the basement up into a family room which is two story, so it's open to the upstairs.   So the pellet stove can heat the whole house. (4300 sf)   The central systems are still available as well as a big ceiling fan in the tall family room for additional mixing if desired.      The 2 fans are located right above the pellet stove.    This is the same concept we are discussing, just a different heat source.      


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