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Ed Janowiak Eastern Heating & Cooling Council

Manual J Fundamentals. Ed Janowiak Eastern Heating & Cooling Council. eh-cc.org. If nothing else……. I promise everyone what I’m going to tell is 100% true, not opinion it’s fact…. Why use Manual J ?. Provide Specified comfort and humidity control at design conditions

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Ed Janowiak Eastern Heating & Cooling Council

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  1. Manual J Fundamentals Ed Janowiak Eastern Heating & Cooling Council eh-cc.org

  2. If nothing else……. I promise everyone what I’m going to tell is 100% true, not opinion it’s fact….

  3. Why use Manual J ? • Provide Specified comfort and humidity control at design conditions • Provide Specified comfort and humidity control at part-load conditions • Provide reasonable comfort at outdoor design conditions • Reduce possibility of Mold and Mildew

  4. Benefits of a Detailed and Accurate Load Calculation • Optimize installed cost • Reduced operating costs • Improved reliability (minimize short cycling) • Translate to smaller duct airways and increased duct system efficiency • Minimize service loads imposed on utility grids

  5. continued…. • Translates to competitively priced proposals and quotes • Minimize “surprises” after the system is put into operation (problems with comfort , mold, mildew, health, safety, and operating cost or a letter from a lawyer) • Demonstrate “due diligence” in a court of law • Provide design values for sensible and latent equipment capacity

  6. Benefits of an over-sized system <insert sound of crickets chirping here>

  7. How do you size equipment?

  8. The finger method ?

  9. The finger method

  10. The finger method

  11. 2 & 1/4 fingers or a 2.5 ton house

  12. Square Foot per ton?

  13. Here’s 1 reason square footage per ton is BS

  14. A little house 400 sqft 400 sqft 400 sqft 10x40 20x20

  15. 20+ 20= 80’ 20+ 20+

  16. 40+ 10= 100’ 10+ 40+

  17. So right there………….. 80 running feet vs. 100 running feet but both spaces are 400 square feet

  18. That same little house 400 sqft 400 sqft 400 sqft 10x40 20x20

  19. Windows 400 sqft Lots of glass

  20. 400 sq ft Windows Very little glass

  21. How do those 2 spaces compare? Yah, you’re right …. they don't

  22. What does Manual J really do?

  23. Manual J Load Calculations • Heat loss and Cooling gain @ design conditions • Accuracy important! • Q = U x A x T • Internal load • Ventilation load • Infiltration • These, and lots more too

  24. ` MJ8AE Speed Sheet current version

  25. Written form

  26. Remember • We don’t design to historic highs • We don’t design to historic lows • Do you want a system that is at it’s best <10% of the time? • Or do we want a system that is at it’s best > 90% of the time?

  27. Page 94 Table 1A

  28. Page 94

  29. This is the example house we are doing West South 12x5=60 3x5x3=45 3x7=21 3x4x3=36 BW FD 3x4=12 Return FP Supply House 50 X 35 8’ walls 3x4=12 3x4=12 3x3.33=10 3x4x2=24 7x6=42 R-19 Ceiling Double pane operable window – metal – W/ break R-11 Walls Dark Roof R-11 Floors (over crawlspace) Ducts in crawl R-6 Front door (FD) Metal fiberglass W/ storm 3’over hang front and back (N&S) all windows 1 foot from sofit, Bay Window (BW) has no overhang

  30. OK, Where do we start? • Doors • Walls • Glass • Ceilings • Floors • Lets just hit the tabs in order.

  31. The Doors No this kind

  32. This is the example house we are doing West South 12x5=60 3x5x3=45 3x7=21 3x4x3=36 BW FD 3x4=12 Return FP Supply House 50 X 35 8’ walls 3x4=12 3x4=12 3x3.33=10 3x4x2=24 7x6=42 R-19 Ceiling Double pane operable window – metal – W/ break R-11 Walls Dark Roof R-11 Floors (over crawlspace) Ducts in crawl R-6 Front door (FD) Metal fiberglass W/ storm 3’over hang front and back (N&S) all windows 1 foot from sofit, Bay Window (BW) has no overhang

  33. page 111

  34. Windows are next

  35. West South 12x5=60 3x5x3=45 3x7=21 3x4x3=36 BW FD 3x4=12 Return FP Supply House 50 X 35 8’ walls 3x4=12 3x4=12 3x3.33=10 3x4x2=24 7x6=42 R-19 Ceiling Double pane operable window – metal – W/ break R-11 Walls Dark Roof R-11 Floors (over crawlspace) Ducts in crawl R-6 Front door (FD) Metal fiberglass W/ storm 3’over hang front and back (N&S) all windows 1 foot from sofit, Bay Window (BW) has no overhang

  36. page 103 double

  37. Walls

  38. West South 12x5=60 3x5x3=45 3x7=21 3x4x3=36 N 34 SQ’ BW N 42 SQ’ FD E/W 36 SQ’ 3x4=12 S 60 SQ’ S 81 SQ’ Return 253 SQ’ FP Supply Of glass (don’t forget the front door) 8’ walls House 50 X 35 3x4=12 3x4=12 3x3.33=10 3x4x2=24 7x6=42 R-19 Ceiling Double pane operable window – metal – W/ break R-11 Walls Dark Roof R-11 Floors (over crawlspace) Ducts in crawl R-6 Front door (FD) Metal fiberglass W/ storm 3’over hang front and back (N&S) all windows 1 foot from sofit, Bay Window (BW) has no overhang

  39. Page 112

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