ACCA MANUAL J PDF
ACCA Manuals J, S, and D are referenced and required across America. pdf file. Understanding & Using the System Design Review Form. For residential applications, ACCA's Manual J, Eighth. Edition (MJ8™) is the only procedure recognized by the. American National Standards Institute (ANSI). Load Calculation: Manual J. Equipment Selection: Furnace and Air Conditioner. This example illustrates a permit application packet when the HVAC Contractor.
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ACCA Manual J - Residential Load Calculation - Download as PDF File .pdf) or read online. ACCA Manual J - Residential Load Calculation. resourceone.info - Free download as PDF The Eighth Edition of Manual J (MJ8 ACCA/ ANSI) is the American National. Manual J to accurately perform a load calculation. This manual is designed . Sizing rules for air conditioners (ACCA). • Air conditioner - May be sized up to.
The software is pretty easy to use given it's complexity but the real benefit is the service. Tech support is friendly and patient, the 10 day training course was perfect for a novice user and the trainer was open and understanding - the kind that doesn't make you feel stupid and knows his stuff so well he can explain why the software is doing what it is doing.
A great overall experience! I've attended several classes, been to the World Headquarters in Lexington, and even hosted training classes. The level of support is phenomenal. Both in the classroom, call in and email. I've used the Right J, Right Draw modules extensively in the new construction markets not only for the purpose intended, but also to "value engineer" the materials selection process for my clients. I can't imagine a better product. The learning curve is pronounced and requires commitment on the part of the user, but with constant use it becomes almost second nature.
Within the past year, we have actually picked up new accounts because our customers were so impressed by the professionalism of our designs, particularly when we go up against contractors who are giving them what amounts to a crayon rendition on a napkin. For a standard 3, square foot, 4 bedroom house, doing the load calculations manually would take many hours.
Then I found Wrightsoft, and by using their Right-J and Right-D, I was able to produce load calculations and duct design in about an hour. Use the full version of Manual J for all other scenarios. Section 2 In general, take full credit for the rated or tested performance of construction materials, insulation materials and construction features.
Follow Manual J procedures for infiltration and ventilation a Use the Table 8A procedure to evaluate the fresh air requirement. Take full credit for duct system sealing and duct insulation when such efforts are confidently anticipated or certifiable. Match location as close as possible when selecting a duct load table use Table 7 unabridged if the MJ8AE tables do not provide a satisfactory match. Match duct system geometry radial and spider systems tend to have less surface area than extended plenum and trunk and branch systems.
Match return system geometry use advanced Manual J procedures when the system has more than one or two large returns or when the returns are not located close to the air handler. Be sure to use the duct wall insulation correction if the R-value of the insulation is not R Be sure to use the surface adjustment factor for the exposed duct surface area when the surface area of the actual duct system is significantly different than the defaults listed in Table 7. Add blower heat to the sensible load if equipment performance data is not adjusted for blower heat if equipment manufacturer or blower power is unknown, assume 1, Btuh for indoor blower motor heat.
Educate consumers: Sit down with your customers or clients and educate them on these issues. Manual J Donts Mandatory Requirements n Do not use Manual J any version for: a Any type of commercial application even if located in a residential structure.
Rotating the dwelling on a site can change the cooling load by a half ton or more. Room airflow requirements change as the orientation changes. If the same design is used for any orientation, some rooms may have too much supply air and other rooms will not have enough supply air for temperature control and comfort.
The panel heating load is Btuh.
There is SqFt of gross area with 70 SqFt of window and door area. Use advanced Manual J procedures for this type of construction. The panel heating load is 1, Btuh. The wall is 8 ft high and has Ft of gross wall area.
The basement floor is 6 feet below grade 2 feet of the wall is above grade. The heating load for the below grade wall area is 1, Btuh, and 1, Btuh for the above grade strip. RG is the grains of moisture at the return grille which defaults to the grains value for the conditioned space. Section 27 This value is determined by Table 12, or use altitude sensitive psychometric software.
LScfm is the supply-side leakage Cfm. SA is the surface area of the exposed supply duct SqFt. LRcfm is the return-side leakage Cfm. RA is the surface area of the exposed return duct SqFt. SHL is the latent heating load for supply moisture loss. OG is the grains of moisture for outdoor air at the winter design condition. This value is determined by Table 12, or use altitude sensitive psychometric software. RHL is the latent heating load for return moisture loss.
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AG is the grains of moisture in the ambient air that contacts the return duct. This defaults to OG if the unconditioned space is not tightly sealed no regain , or may be about equal to RG if the unconditioned space is tightly sealed. THL is the total latent heating load.
SML is the supply-side moisture loss. RML is the return-side moisture load. TML is the moisture load for both sides of the duct system.
Per Table 12, there are 4. The design humidification load for infiltration and ventilation is 6. The duct runs are in a vented attic, and 1, Cfm flows through the duct system.
The supply-side surface area is SqFt and the return-side surface area is SqFt. Humidification loads are compared for ducts that are exceptionally tight 0. Figure shows the solutions for the first iteration and for the second and final iteration. Note that the humidification load is very sensitive to duct leakage and much less sensitive to the iteration.
Duct Leakage Loads -- Iteration 1 6. Moisture Migration Load Procedure Moisture migration can have a significant affect on the latent cooling load and the winter humidification load.
In addition, it can cause concealed condensation with attendant mold and mildew or structural damage problems. This flow of water vapor produces a latent moisture migration load MML on cooling equipment during the cooling season. This load shall be evaluated when one or more of the dwelling's opaque panels ceilings, walls and exposed floors has permeable construction that is not protected by a vapor retarding membrane..
Refer to Table 13 for permanence values that are compatible with this equation and the Table 1 grains difference value for the site location. For example, a handbook value of Use the following equations to convert a Perm or Permeability rating to a Perm rating for a desired thickness.
The ceiling is covered by blanket insulation that has negligible resistance to moisture migration. There is no vapor retarding membrane. This value increases somewhat with altitude, but this effect is relatively small, and may be ignored. A latent cooling load is not an issue for higher elevations see the Table 1 grains difference values. A winter humidification load is a design possibility for any elevation.
For unapproved construction, the moisture migration load MML is evaluated by using Table 12 to obtain a grains difference value for the winter design condition and the site elevation or use altitude sensitive psychometric software. Outdoor design temperature provided by Table 1. Reference area provided with construction number. Heating Exceptions Number 15 Basement walls may be partly above grade and partly below grade: Outdoor design temperature and daily range provided by Table 1.
Partition wall for closed garage Partition wall for closed sunroom Ceiling below an encapsulated attic. Hollow Core B. Hollow Core with Wood Storm C. Hollow Core with Metal Storm D. Solid Core E. Solid Core with Wood Storm F.
Solid Core with Metal Storm G. Panel H. Panel with Wood Storm I. Panel with Metal Storm Metal Door. Construction Number 15 Basement Walls Block open or filled core , brick, concrete, insulated concrete form and plywood panel Insulation options: None, closed cell foam board, framing with cavity insulation blanket or fill and board-cavity combinations Insulation coverage code: Eight inches brick or stone, framing with R in 2 x 4 cavity, no board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 4 cavity, no board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 4 cavity, no board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 6 cavity, no board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 6 cavity, no board insulation, plus interior finish.
Eight inches brick or stone, framing with R in 2 x 4 cavity, R-4 board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 4 cavity, R-8 board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 4 cavity, R-4 board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 4 cavity, R-8 board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 6 cavity, R-4 board insulation, plus interior finish Eight inches brick or stone, framing with R in 2 x 6 cavity, R-8 board insulation, plus interior finish.
Unvented or vented to FHA specifications, or attic fan, or extra attic vent area. Roofing material options: Asphalt shingles, wood shakes, tile, slate, metal, concrete, tar and gravel or membrane. Roof color options: Dark, red or solid bold color; light color, light gray, silver or unpainted metal and white see absorptivity notes. Attic fan Extra attic vent area. Table 4C Approximate Ambient Temperature in a Closed Garage The temperature rise values provided by Table 4C are approximations see the table notes that can be used to estimate partition heating load and cooling load for the listed scenarios.
Rough estimates for ambient space temperatures are suitable for this task because partition loads are relatively small when compared to the total load. For example, if the partition load is 3 percent of the total load, a 20 percent error in the partition load translates to a less than 1 percent error in the total load. The temperature rise values for scenarios that are significantly different than the listed scenarios are provided by the heat balance procedure that appears in Section 18 of the unabridged version of Manual J.
Garage 1: Two car garage, no significant glass area, one insulated partition wall, garage walls have no insulation, uninsulated garage ceiling under vented attic. Detail Used for Garage 1 Estimate Garage: Slab floor area: None Exterior finish: Brick, siding or stucco Interior finish: Plasterboard Glass in exterior walls: Below vented attic Attic roof: Dark asphalt shingles Ceiling insulation: None Ceiling finish: None Adjustment for vehicle cool-down: R Finish: Plaster board on both sides Glass area: None Entrance door: Insignificant issue.
Garage 2: Two car garage, no significant glass area, conditioned space above garage, insulated ceiling partition, one insulated partition wall, garage walls have no insulation. A conditioned space above a garage should be a separate zone. Detail Used for Garage 2 Estimate Garage: Ceiling area; R-value of ceiling insulation: Sunroom 1: Primary exposure faces South, 24 Ft wide by 12 Ft deep, sunroom walls are 60 percent double-pane clear glass no external or internal shade , sunroom walls and ceiling are insulated, one insulated partition wall with sliding glass door.
Sunrooms should be architecturally and mechanically isolated from the main living space. If conditioned, heating and cooling should be provided by a separate system. Detail Used for Sunroom 1 Estimate Sunroom: R Exterior finish: Double-pane clear; wood frame, no shades Overhang adjustment: None Window position: Closed Ceiling type: Below vented truss space.
R Ceiling finish: Plaster board on both sides Glass door area: Double-pane clear; wood frame Overhang: Shaded by sunroom ceiling Glass door is closed.
Temperature rise values are daily averages. Hourly values may be larger or smaller. Sun Room 2: Primary exposure faces South, 24 Ft wide by 12 Ft deep, sunroom walls are 60 percent spectrally-selective glass no external or internal shade , sunroom walls and ceiling are insulated, one insulated partition wall with sliding glass door. Detail Used for Sunroom 2 Estimate Sunroom: Below vented truss space Roof: Encapsulated Attic: Attic space roof and gable ends sprayed with R insulating foam. Attic space sealed no vents, infiltration 0.
Attic floor is uninsulated plasterboard ceiling of conditioned space below the attic. Attic floor area: R Gable wall finish: Brick, siding or stucco Ceiling type: Below encapsulated attic Attic roof: Dark asphalt shingles Attic roof insulation: R Attic floor: Partition ceiling: No insulation Finish: Plaster board.
The ambient air condition depends on the actual construction details. Section provides guidance for estimating the temperature of an unconditioned space buffer zone. The ceiling below an encapsulated attic is a partition that separates a conditioned space from an unconditioned space. So, the ceiling load for heating depends on the U-value of the ceiling panel, on the partition temperature difference for heating PTDH , and the ceiling area; and the ceiling load for cooling depends on the U-value of the ceiling panel, on the partition temperature difference for cooling PTDC , and the ceiling area.
Table 4E shows that the ambient temperature in an encapsulated attic is benign and relatively constant for heating and cooling. Foam seals attic cracks, so attic humidity is similar to indoor humidity.
Tables 7M and 7N provide duct load factors and latent loads for ducts runs in an encapsulated attic. Comments on these tables are provided here. Attic behavior should be similar to Table 4E. For heating, the ambient temperature is relatively steady as outdoor temperature increases, so the duct load is a lager portion of the total load as outdoor conditions moderate. For cooling, the ambient temperature is relatively steady as outdoor temperature decreases, so the sensible duct load is a lager portion of the total sensible load as outdoor conditions moderate.
Include a surface area adjustment when duct surface areas are known or estimated. Square Feet of Floor Area 0. Select the default heat loss factor or the default sensible gain factor. Step 2: Apply R-value correction to default value. Step 3: Apply leakage correction to Step 2 value.
Step 4: Apply the surface area adjustment to the Step 3 value. Procedure for Latent Gain Adjustment Step 1: Select the default latent gain factor. Apply leakage correction to Step 1 value. Apply surface area adjustment to the Step 2 value.
Notes 1 This table provides load factors for systems that features one large return because such designs are common but not recommended by ACCA. Use the data for leakier scenarios to evaluate the benefit of the sealing work.
Trunk and branch with outlets in center of rooms. Radial with outlets at perimeter of rooms. Radial or trunk and branch with outlets at perimeter of rooms. Radial, CFM per return, returns close to air handler. Trunk and branch, CFM per return, returns close to air handler. Single ceiling return close to air handler. Closet air handler, return in closet door. Grille at floor of conditioned space, return riser to attic air handler.
Radial or trunk and branch, CFM per return, returns close to air handler. Trunk and branch with outlets at perimeter of rooms. One or two floor returns, close to air handler.
Radial with outlets at room perimeter. No supply leakage. Sealing options apply to the return runs. Return system in conditioned space. Radial system in attic, CFM per return, returns close to air handler. Radial with outlets in center of rooms. Closed crawl space below insulated floor, no wall insulation.
Unconditioned basement or closed crawl space with: Return runs in conditioned space or in attic. Riser or drop in exterior wall. Rectangular or round airway Radial, CFM per return, returns close to air handler. Radial, 1, CFM per return, returns close to air handler. Floor plan size and duct system geometry determine the default heating cooling loads, the default blower Cfm, and the duct surface area defaults.
The default surface areas for these duct tables are compatible with systems designed by Manual D procedures. ACCA recommends sealing duct systems that have leakage rates greater than the 0. Use leakier scenarios to evaluate sealing benefit.
Table 7 Notes 1 The Table 7 load factors account for the conduction loads and leakage loads that occur on the supply and return sides of the duct system. These factors also include an adjustment for an increase or decrease in the envelope infiltration load per a set of power law equations , depending on the relative amount of supply-side and return-side leakage.
The load factors and latent load values are compatible with duct system surface areas generated by theManual D sizing pro- cedure and the five default leakage ratesprovided by Table 7. Computerized duct load solutions models are required for duct systems that have dominant return side leakage or a leakage rate that is substantially different than the default values.
These factors tend to get smaller as the discharge temperature increases because by the sensible heat equation the supply CFM values and airway sizes exposed area get smaller as the supply temperature increases. Table 7 uses a F default for discharge temperature because it produces conservative duct load values and because the heat loss factors are compatible with airway sizes required for cooling.
Computerized duct load solutions models are required for other supply air temperatures. The Table 7 data is based on assumptions pertaining to the floor plan of the home, the location of the air handler, the number of supply runs, the number of the return runs and a set of leakage rate values.
These assumptions are listed here. Rectangular floor plan with a 2: Air handler located in the center of the floor plan. One supply branch per CFM of supply air.
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Supply ducts not sealed 0. Return ducts not sealed 0. Supply ducts sealed 0. Return ducts sealed 0. Duct runs below the slab have no leakage and are water tight. The leakage occurs along the above grade duct runs. For heating, the default value for ambient dry-bulb temperature for duct on a roof equals the Table 1A or1B value. For cooling, the default value for ambient dry-bulb temperature for duct on a roof depends on the color of the outside surface of the duct, and weather the duct is in the sun or shade.
Performance should be certified by test or quality control program before taking credit for this type of sealing effort. Duct tape is not and approved sealing method. Sealing work must conform to industry standards. If a duct run is located behind an attic knee wall or between the joists in a roof-ceiling sandwich, use Table 7A.
If the load estimating software performs an energy balance on an unconditioned space, the estimated space temperature should be used to generate load factors for the duct runs that pass through the space providing the software use the Manual J duct load model, see note See Worksheet G1.
This procedure applies to all the exposed-wall load factors heating percentage, cooling percentage or latent load value. Note that the load factor for a two-story riser or drop is twice the single-story value, etc..
Then repeat the process for Sections 8 and 9.
Refer to Sections 3 and 6; and Appendices 4, 7, 8 and 9, as required. Learn to use the MJ8AE spreadsheet redo the example dwellings in the book, or investigate a simple dwelling that is available for survey. Read Sections 2 and Appendix 6 internalize this guidance Go to Appendix 2 and read the capabilities and sensitivities material.
Make sure that you understand the limitations of MJ8AE. Read Appendix 3 and make sure you understand these concepts. Make sure you understand the limitations of MJ8AE. Read the Introduction of this manual and internalize this guidance.
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Read Section 10 and acquire the necessary knowledge and skills. Pay particular attention to the error checking procedure. Therefore, HTM values for.
See advanced procedures for: AED excursions are common, even for fenestration plans that seem to have begin attributes. The AE procedure will not be equivalent to the full procedure if the dwelling's AED excursion is greater than zero. There is no simple way to simulate the information provided by the AED curve, and no simple way to estimate the AED excursion value. When using Manual J for attic duct systems, make sure the Table 4A construction number for the attic ceiling and the Table 7 option 7A through 7F are compatible.
Note 3: For duct loads, "Powered by Manual J" software can be used to evaluate the attributes of the "as-installed" system user-specified R-values, sealing options and surface areas. As such, it introduces the procedures used to estimate residential heating and cooling loads. Mastery of the material in MJ8AE is a prerequisite for using third party software products that perform Manual J calculations. This presentation assumes the practitioner is acquainted or will become familiar with the basic principles of mathematics and heat transfer; and is conversant with Manual S, Manual D and Manual T design procedures.
A Limitations and Guidelines System design plays an important role in the comfort, health and safety of the occupants. MJ8AE may be used to estimate heating and cooling loads for residential applications that have these attributes. Architecture and Occupancy Single family detached dwellings shall have a normal amount of fenestration total area of windows, glass doors and skylights shall not be more than 15 percent of the floor area.
Windows and glass doors shall be reasonably distributed around the dwelling. The dwelling shall have adequate exposure diversity see Appendix 3. There shall be no excursion adjustment for the sensible fenestration load see Appendix 3.
Simple default values shall be used for the occupancy loads and appliance load. Use advanced Manual J procedures for applications that do not have these attributes.
Comfort System n A central, single-zone air system, or electric baseboard elements shall provide heat. Windows and Glass Doors n Window and glass doors shall have clear single, double or triple pane glass. Window and glass door framing shall be metal, metal with break, wood or vinyl.
Windows can have a fixed or operable sash sliding glass doors have an operable sash. Windows and glass doors shall not be equipped with external sun screens. The foreground reflectance for window and glass door heat-gain shall be 0.
Use advanced Manual J procedures for Fenestration rated by the NFRC, for other internal and external shading options, for other foreground reflectance options, and for latitude-adjusted HTM's for generic fenestration.
Skylights n Skylights shall have clear single pane or double pane glass. Walls n Above grade wall construction shall be woodstud frame or empty-core block. Ceilings and Attic Knee Walls n The ceiling options shall be attic ceiling, ceiling on exposed beams or joist ceiling sandwich.
Knee walls shall be installed in a FHA-vented attic space. Use advanced procedures for other types of roofing material, roof color, attic with radiant barrier, encapsulated foam, unvented attic or knee-wall space.
Floors n All floors shall be passive no heating elements below the floor. Duct System n A duct system shall be entirely in the conditioned space, or shall be compatible with one of the system scenarios in Figure of Section 1. Engineered Ventilation n Engineered ventilation may be provided by piping a small amount 50 Cfm or less of fresh air to the return-side of the duct system. The engineered ventilation system shall not have a heat recovery device or a ventilation dehumidifier.
Use advanced Manual J applications for engineered ventilation systems and ventilating dehumidifer equipment. Other Loads n Internal load choice of two default values n Blower heat one default value n Use Section 22 procedures for other internal load options occupants, appliances, lighting, etc.
A Procedural Defaults Procedural complexity increases in proportion to sensitivity to variations in construction detail. Defaults simplify the procedure and make hand calculations possible.
Design Conditions n Indoor: Use values in Table 1A unless superceded by code. Windows and Glass Doors n Purpose-built daylight windows and skylights shall have no internal shade. Skylights n Curb construction shall default to un-insulated wood 2x4; four inches high. Appendix 4 and latent capacity. Supply-side gains reduce the cooling capacity of the airflow delivered by the supply air outlets.
Duct loads are caused by conduction through the duct wall and by leakage. Duct leakage also causes negative or positive pressure in the conditioned space. The space pressure condition depends on the difference between the return side leakage rate and the supply side leakage rate. If the return side leakage rate is greater than the supply side leakage rate, there is a net flow of air from outside the conditioned space to the conditioned space.
This causes a positive pressure in the conditioned space, exfiltration from the conditioned space and a direct load on the central equipment the air that leaks into the return duct passes through the central equipment before it enters the conditioned space. If the supply side leakage rate is greater than the return side leakage rate, the flow rate through the return grilles is greater than the flow rate through the supply outlets. This causes a negative pressure in the conditioned space, the infiltration to the conditioned space is increased and the load on the central equipment is larger.
The heating and sensible cooling loads generated by duct systems are sensitive to a collection of parameters and interactions that include the piping geometry, the location of the duct runs, the temperature and moisture content of the air in the duct runs, the temperature and moisture content of the air in the surrounding environment, the tightness of seams and joints and the amount of duct-wall insulation. Duct loads also depend on the size of the dwelling and the construction details because equipment size, blower CFM, the size of the duct airways and the total surface area of the duct system depend on the size of the heating and cooling loads.
An attic is a hostile environment for duct runs if attic temperature is significantly higher than the outdoor temperature in the summer white shingles, tile roofs, radiant barriers and foam encapsilation moderate this condition ; and almost as cold as the outdoor air in the winter.
In addition, the absolute humidity in a properly vented attic is about the same as the outdoor humidity the absolute humidity in a foam encapsulated attic will be closer to the conditioned space value. Open crawlspace locations are undesirable because there is little difference between the crawlspace condition and the condition of the outdoor air.Trunk and branch with outlets at perimeter of rooms.
For unapproved construction, the moisture migration load MML is evaluated by using Table 12 to obtain a grains difference value for the winter design condition and the site elevation or use altitude sensitive psychometric software.
Use of this set of conditions is mandatory, unless superceded by a code, regulation or documented health requirement. Heating and cooling is, or shall be, provided by a central, single-zone, constant volume system. For example, software-generated values for C and n for the Figure blower door test are A Procedural Defaults Procedural complexity increases in proportion to sensitivity to variations in construction detail.