1 ed janowiak eastern heating & cooling council eh-cc.org

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Ed JanowiakEd JanowiakEastern Heating & Cooling CouncilEastern Heating & Cooling Council

eh-cc.org

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If nothing else…….If nothing else…….

I promise everyone what I promise everyone what I’m going to tell is 100% I’m going to tell is 100% true, not opinion it’s true, not opinion it’s fact….fact….

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Why use Manual J ?Why use Manual J ?

Provide Specified comfort and humidity Provide Specified comfort and humidity control at design conditionscontrol at design conditions

Provide Specified comfort and humidity Provide Specified comfort and humidity control at part-load conditionscontrol at part-load conditions

Provide reasonable comfort at outdoor Provide reasonable comfort at outdoor design conditionsdesign conditions

Reduce possibility of Mold and MildewReduce possibility of Mold and Mildew

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Optimize installed costOptimize installed cost Reduced operating costsReduced operating costs Improved reliability Improved reliability (minimize short cycling)(minimize short cycling)

Translate to smaller duct airways and Translate to smaller duct airways and increased duct system efficiencyincreased duct system efficiency

Minimize service loads imposed on Minimize service loads imposed on utility gridsutility grids

Benefits of a Detailed and Benefits of a Detailed and Accurate Load Calculation Accurate Load Calculation

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continued….continued…. Translates to competitively priced proposals Translates to competitively priced proposals

and quotesand quotes Minimize “surprises” after the system is put into Minimize “surprises” after the system is put into

operation (problems with comfort , mold, operation (problems with comfort , mold, mildew, health, safety, and operating cost or a mildew, health, safety, and operating cost or a letter from a lawyer)letter from a lawyer)

Demonstrate “due diligence” in a court of lawDemonstrate “due diligence” in a court of law Provide design values for sensible and latent Provide design values for sensible and latent

equipment capacityequipment capacity

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Benefits of an over-sized Benefits of an over-sized systemsystem

<insert sound of crickets chirping <insert sound of crickets chirping here>here>

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How do you size equipment?How do you size equipment?

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The finger method ?The finger method ?

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The finger methodThe finger method

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The finger methodThe finger method

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2 & 1/4 fingers or a 2 & 1/4 fingers or a 2.5 ton house2.5 ton house

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Square Foot per ton?Square Foot per ton?

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Here’s 1 reason square Here’s 1 reason square footage per ton is BSfootage per ton is BS

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A little houseA little house

400 sqft

400 sqft

400 sqft

20x2010x40

161620+

20+

20+

20= 80’

1717

40+

10+

40+

10= 100’

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So right there………….. So right there………….. 80 running feet vs. 100 80 running feet vs. 100

running feet running feet but both spaces are 400 but both spaces are 400

square feetsquare feet

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That same little houseThat same little house

400 sqft

400 sqft

400 sqft

20x2010x40

2020

Windows

400 sqft

Lots of glass

2121

400 sq ft

Windows

Very little glass

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How do those 2 spaces compare?How do those 2 spaces compare?

Yah, you’re right …. they don'tYah, you’re right …. they don't

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What does Manual J really do?

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Manual J Load CalculationsManual J Load Calculations

Heat loss and Cooling gain @Heat loss and Cooling gain @design conditionsdesign conditions Accuracy Accuracy important!important! Q = U x A x Q = U x A x TT

Internal loadInternal load Ventilation loadVentilation load InfiltrationInfiltration These, and lots more tooThese, and lots more too

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`̀

MJ8MJ8AEAE

Speed Sheet Speed Sheet current current versionversion

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Written formWritten form

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RememberRemember

We don’t design to historic highsWe don’t design to historic highs We don’t design to historic lowsWe don’t design to historic lows Do you want a system that is at Do you want a system that is at

it’s best <10% of the time?it’s best <10% of the time? Or do we want a system that is at Or do we want a system that is at

it’s best > 90% of the time?it’s best > 90% of the time?

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Page 94 Table 1A

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Page 94

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SouthWest

7x6=42

12x5=60

House 50 X 35

R-19 CeilingR-11 WallsR-11 Floors (over crawlspace)

Double pane operable window – metal – W/ breakDark RoofDucts in crawl R-6 Front door (FD) Metal fiberglass W/ storm

FD

3x7=213x5x3=45 3x4x3=36

3x4=12

3x4=12

3x4x2=24

3x4=12

SupplyReturn

3x3.33=10

BW

3’over hang front and back (N&S) all windows 1 foot from sofit, Bay Window (BW) has no overhang

8’ walls

This is the example house we are doing

FP

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OK, Where do we start?OK, Where do we start?

DoorsDoors WallsWalls GlassGlass CeilingsCeilings FloorsFloors Lets just hit the tabs in order.Lets just hit the tabs in order.

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The Doors

No this kind

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SouthWest

7x6=42

12x5=60

House 50 X 35



FD

3x7=213x5x3=45 3x4x3=36

3x4=12

3x4=12

3x4x2=24

3x4=12

SupplyReturn

3x3.33=10

BW


8’ walls

This is the example house we are doing

FP

4040

page 111

4242

Windows are next

4343

SouthWest

7x6=42

12x5=60

House 50 X 35



FD

3x7=213x5x3=45 3x4x3=36

3x4=12

3x4=12

3x4x2=24

3x4=12

SupplyReturn

3x3.33=10

BW


8’ walls

FP

4444

page 103

double

4848

Walls

5151

SouthWest

7x6=42

12x5=60

House 50 X 35



FD

3x7=213x5x3=45 3x4x3=36

3x4=12

3x4=12

3x4x2=24

3x4=12

SupplyReturn

3x3.33=10

BW


N 34 SQ’N 42 SQ’

E/W 36 SQ’

S 60 SQ’S 81 SQ’

253 SQ’Of glass

(don’t forget

the front door)

8’ walls

FP

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Page 112

5757

page 18

6262Manual S

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Sizing LimitationsSizing LimitationsCooling-only equipment should be sized so that Cooling-only equipment should be sized so that

the total cooling capacity does not exceed the the total cooling capacity does not exceed the total cooling load by more than 15%.total cooling load by more than 15%.

If heat pump equipment (air-source or water-If heat pump equipment (air-source or water-source) is installed in a warm or moderate source) is installed in a warm or moderate climate, the total cooling capacity should not climate, the total cooling capacity should not exceed the total cooling load by more than 15%.exceed the total cooling load by more than 15%.

If heat pump equipment is installed in a cold If heat pump equipment is installed in a cold climate (where heating cost are a primary climate (where heating cost are a primary concern), the total cooling capacity may exceed concern), the total cooling capacity may exceed the total cooling load by as much as 25%.the total cooling load by as much as 25%.

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““My unit runs constantly when it’s My unit runs constantly when it’s hot or cold out, it never shuts off”hot or cold out, it never shuts off”

Great!Great! It’s supposed too, I guess I did it right… It’s supposed too, I guess I did it right…

yippee!!!!!!yippee!!!!!! It’s our job (or our students) to educate the It’s our job (or our students) to educate the

consumerconsumer

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Is Manual J always the way to go?Is Manual J always the way to go?

NoNoYou have to have reasonably You have to have reasonably

tight ductstight ductsAdequate air flowAdequate air flowRight chargeRight charge

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Seal-tight fittingsSeal-tight fittings

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A little masticA little mastic

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Correctly charged Correctly charged

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Manual J Manual N

Use these

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Guess at sizing Guess at sizing and you’ll end up and you’ll end up

too big or too too big or too smallsmall

7878

Too big……Too big……

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Too smallToo small

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Just rightJust right

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Questions?Questions?

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MJ8 unabridged software vendersMJ8 unabridged software venders

In no specific orderIn no specific order Elite www.elitesoft.comElite www.elitesoft.com Adteck www.Adteck www.adtekadteksoft.comsoft.com Nitek www.niteksoftware.comNitek www.niteksoftware.com Wrightsoft www.wrightsoft.comWrightsoft www.wrightsoft.com

Free demos for each at their sitesFree demos for each at their sites

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Heat only applications?Heat only applications?

If you want to learn more about heat loads.If you want to learn more about heat loads. If you want to learn more about duct sizingIf you want to learn more about duct sizing If you just want to learn more on almost If you just want to learn more on almost

anything in the HVAC/R.anything in the HVAC/R. Contact us ( Contact us ( Training for the Trades Training for the Trades )) Web Web www.tftt.org E-mail E-mail [email protected] Phone 24/7 859-468-6000Phone 24/7 859-468-6000

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1 ed janowiak eastern heating & cooling council eh-cc.org

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