Purpose• Reduce energy usage within the home by recovering heat from

attic . and using it to supplement the house heating system

Problem Statement• Design and develop a control system that will enable a whole

house . fan to recover heat from a hot attic and return it to living space

• Predict attic temperatures and determine fan operating conditions• Estimate a yearly cost savings associated with recovered heat• Develop market and advertising strategies for product release

• 20” Plastic duct added to fan• Decreases chance of debris pickup• Increases fan access to warm air layer at top of attic

Metal strip for strength

Ducting before and after metal strip was added Attic temperature distribution from Florida study

Ducting

Heat Transfer Analysis:Model predictions based on Florida Temperature Study

Operating Range

Attic/Ambient Air Temperature Distinction

40

50

60

70

80

90

100

110

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hour

De

gre

es

(oF

)

Average Ambient Air Temperature = 80°F Attic Temperature for 80°F Day

Average Ambient Air Temperature = 55°F Attic Temperature for 55°F Day

Completed an energy balance to check temperature predictions

with new temperature study data

Whole House Fan With Latent Heat RecoveryME 481 Multi-College Program

EngineeringAndrew GillettChad KleinowAndrew KrukKevin McKay

Marketing / AdvertisingChrystal KozseyMelissa PoirierAlyse Solomon

Academic AdvisorsDr. Brian S. ThompsonDavid ReganMichael F. Lobbestael

Project SponsorBob LaZebnikAirmaster Fan Company

Special Thanks to:Dr. Gregory Wierzba - ECE Brian Wright - ECEDr. Neil T. Wright - ME Todd Burghgraef – DornerWorks

Specification• Supplement current HVAC System• Solid State Controls• Regulate operation of fan based on seasonal setting and

. temperature data• Minimal input from user after initial setup• System should be cost effective and provide energy savings to

. customer

Fluid Dynamics:• Computational Fluid Dynamics (CFD) in Fluent• Models examined flow patterns in attic for a variety

. of conditions• Used to validate the need for ducting on fan• Energy equation used to predict temperature

layers and fan run time in addition to heat transfer analysis

Comparison of velocity vectors and temperature for fans with and without ducting

1. Opto22 G4OAC5 Solid State Relays (SSR)

2. Opto22 120D10 SSR(High Speed)3. DS1620 Digital Thermometers

4. BS2 Basic Stamp Microcontroller5. ULN2803A Line Driver6. AO Smith 1/3hp Motor

Capabilities:

Based on: 68oF thermostat setting

Above 75oF in atticBelow 64oF ambient air

Map Key

$2 - $ 4

$4 - $6

$6 - $9

Modeling

Control SystemComponents:

Economic Analysis

Annual Cost Savings by State

Natural Gas LPG LocationMaximum $9.71 $18.49 ArizonaMinimum $2.04 $4.01 New YorkAverage $4.82 $9.18

Number of sunny days within

temperature range

Energy pulled into house per sunny

day

Furnace cost for energy – motor electricity cost

$ Annual Cost Savings

90 days 15,000 kJ / day $10.53 - $0.82 $9.71 per year

Finance Parameters Net Present Value

Profitability Index

Payback Period

Current Energy Prices -$7.20 0.84

9.3 Years

Rising Energy Prices $7.87 1.63

4.82 Years

Average Ambient Temp

(°F)

Average Attic

Temperature

Operation Time Points

52 57.8 1 hours

53 58.9 2 hours

54 60.0 3 hours

55 61.1 4 hours

56 62.2 4 hours

57 63.3 2 hours

58 64.5 3 hours

59 65.6 1 hours

60 66.7 1 hours

 Shingle

Temp (K)Measured Temp (K) Error

Average 310.25 310.97 2.41%

Model is valid!

Summer Mode• Evaluates actual room temperature and

. desired temperature set by user• If the room is too hot, the fan turns on

high . speed exhaust• If the room is too cool, fan does nothing

Winter Mode• Evaluates actual room temperature and

. desired temperature set by user and . compares them to the attic temperature

• Attic must be more than 5 degrees hotter . than the desired room temperature

• Room temperature must be less than desired . temperature

1 1

2

35

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House InformationSize = 1700 sq. feetDark Shingle Roof

Location = Cocoa, Florida

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