[EnergyPlus_Support] Re: Residential Fan Performance

["donbshireyiii" <shirey@xxxxxxxxxxxx>]

1)  For Furnace/AC systems, EnergyPlus currently only allows for the
"blow  through" configuration.  Use FURNACE:BLOWTHRU:HEATCOOL.

For air-to-air heat pumps, one of the input fields sets the fan
location.  Use UNITARYSYSTEM:HEATPUMP:AIRTOAIR, and set field Fan
placement to "draw through".

2)  The fan and motor efficiencies that you are proposing are too high
for residential equipment. Total efficiencies are more like 35% to
45%.  Motor efficiencies depend on type (permanent split capacitor or
ECM). Motor efficiencies tend to be higher for larger commercial size
motors.

3)  Fan pressure difference will be site specific.  Total pressure
difference would probably be somewhere between 150 and 225 pascals for
residential systems.


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Ian Doebber"
<idoebber@v...> wrote:
> I am trying to most accurately model a blow through on/off fan for a
furnace/AC system and a draw through on/off fan for a heat pump
system.  
> 
> 1.  First I am wondering whether I should specify a blow through and
draw through differently.  
> 
> 2. Second, I am wondering what to put for its efficiency.  I have
65% for the total efficiency and 90% for the motor efficiency.  I have
all the motor inefficiency lost as heat to the air stream but wanted
to know what happens to the energy lost due to the fan efficiency.
> 
> 3.  Third, how should I specify my pressure difference across my
fan. I see that Building America specifies that the air handler should
consume 0.00055 kW/CFM.  Therefor, would a good practice be to change
my pressure difference to meet this figure based upon what ever my CFM
is sized to be.
> 
> Thanks
> Ian Doebber
> Graduate Student
> Mechanical Engineering
> Virginia Tech
> 
> [Non-text portions of this message have been removed]



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