The Manual J form is a crucial document used to calculate heating and cooling loads for residential buildings. This form ensures that HVAC systems are properly sized to maintain comfort and efficiency in homes, particularly in Utah's dry climate. To begin your project, fill out the Manual J form by clicking the button below.
The Manual J form plays a crucial role in ensuring that residential heating and cooling systems are designed to operate efficiently and effectively. This form is essential for calculating the heating and cooling loads of a home, taking into account various factors such as the size and layout of the space, local climate conditions, and construction quality. It requires detailed information about the project location, design conditions, and the specific heating and cooling equipment to be used. By breaking down the load calculations on a room-by-room basis, the Manual J form provides a comprehensive understanding of both sensible and latent heat gains, which are vital for determining the appropriate size of HVAC systems. Additionally, it includes sections for documenting the efficiency ratings of heating and cooling equipment, ensuring that the selected systems align with the calculated loads. This form is tailored for homes built in Utah's dry climate, making it particularly relevant for local builders and contractors. Proper completion of the Manual J form not only aids in compliance with building codes but also enhances energy efficiency and comfort within the home.
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Updated 12/2012
BLD # Received by
Date Valuation
Residential HVAC Worksheet
Manual J / S Summary
NOTE: The load calculation must be calculated on a room basis. Room loads are a mandatory requirement for making Manual D duct sizing calculations. This sheet has been developed for homs built in Utah’s dry dimares- do not use for other climate conditions.
Design Information
Project
Location
Design Conditions
Htg
Clg
Altitude
ft
Outside db
°f
Entering wb
Inside db
Assume no higher than 63 °f unless there is ventilation air or significant duct leakage or heat gain
Design TD
If design conditions used are not those listed in Table 1 / 1A Manual 3, please justify.
Infiltration
Method
Construction quality
# of fireplaces
Summary
Manual J heat loss
btuh
Heating fan
CFM
Htg design TD
Temp rise range
to
Latent gain
Total gain
Manual J sensible gain
Cooling fan
Use SHR to determine cooling CFM / ton
Calculated SHR
Heating Equipment
Furnace manufacturer
Model #
AFUE
Sea level: input
Output
Altitude adjusted output
Multistage
If yes, provide
Altitude adjusted lowest output
If “adjusted output” is greater than 1.4 times the “total heating load”, please justify
Cooling Equipment
AC manufacturer
SEER
Total capacity
Sensible capacity
Latent capacity
Evaporator coil manufacturer
TXV
Metering
Actual SEER rating w/ selection coil, furnace, & metering
Attach manufacturer’s data showing actual cooling capacity and actual SEER using these components
If “cooling capacity” is greater than 1.15 times the “total heating load”, please justify
Instructions
The load information asked for on the summary must be taken from the actual load calculation completed on the project.
Identify project name, lot number- information that matches the plan submitted.
The city or town must be reasonably close to actual location. Software used may not have the specific location in the database.
Outside Dry Bulb, Inside Dry Bulb
Temperature data should be from Table 1 or Table 1A of ACCA Manual J. It is understood that there may be situations where a slight adjustment to this values is necessary. For example; there may be areas in the Salt Lake Valley where the low temperature is historically lower than the airport temperature. If values are adjusted- please justify the adjustment. Provide both heating (htg) and cooling (clg) design temperatures. If inside
or outside design conditions listed are not the same values listed in Manual J, explain why the different values were used.
Entering WB
The entering wet-bulb represents the default value wet-bulb temperature across the evaporator coil. This will typically be
63 °f (75 °f dry bulb) relative humidity). A higher wb temperature will result from duct leakage, un-insulated duct or ventilation air- any condition that raises the return
air temperature. Use this wb temperature when selecting cooling condenser from manufacturer’s comprehensive data.
TD: the temperature difference between inside and outside design temperatures.
Infiltration calculations are based on the Construction Quality. Version 7 of Manual ] uses Best, Average or Poor to evaluate Infiltration. Version 8AE uses Tight, Semi-Tight, Average, Semi-Loose and Loose to evaluate. Version 8 goes into very specific detail for a more accurate number. Note method used on summary. Open firebox fireplaces that draw air from inside the home must be included, even if there is a 4” ‘combustion air’ flex bring air into the fireplace. Sealed, direct vent type fireplaces should
not be counted. Methods include: Simplified
/Default Method- taken from Table 5A; Component Leakage Area Method- calculating infiltration based on individual leakage points taken from Table 5C of Manual J8; or Blower Door Method, where the actual leakage is based on a blower door test on the home.
Manual J Heat Loss
This is the whole house winter heat loss taken directly from the completed attached Load Calculation. Load must account for all factors such as loss building components as well as loss through infiltration, ventilation, and duct losses.
Heating Fan
Heating airflow typically may be lower than cooling cfm. Adjusted to insure the temperature rise across the heat exchanger falls within the range specified by the manufacturer. Software will often do this calculation and provide a correct heating cfm. See Manual S Section 2-6 - Rise (°f) = Output Capacity ÷ (1.1 x heating cfm)
Manufacturer’s Temperature Rise Range
Range taken from manufacturer’s performance data. Various manufacturers may certify ranges from 20 - 70 °f.
Manual J — Sensible Gain
The whole house summer heat gain taken directly from the completed attached Load Calculation. Load must account for all factors including gain through building components, solar gain, infiltration, ventilation and ducts. Also includes the sensible internal gains from appliances and people.
Manual 3 — Latent Gain
The gains due to moisture in the air. Large latent load are typically from moisture migration into the home from outside in humid climates. People, cooking, plants, bathing and laundry washing can all add to the latent load in a home.
Total Gain
The combined total of the sensible and latent gain. May be referred to as Total Cooling Load.
SHR- Sensible Heat Ratio
Use to determine Cooling cfm per ton. The ratio of sensible heat gain to total heat gain. SHR = Sensible Heat Gain ÷ Total Heat Gain. Recommended air flows: If SHR is below 0.80 select 350 cfm / ton; if SHR is between 0.80 & 0.85 select 400 cfm; if SHR is greater than 0.85, select 450 cfm
/ton. Note: This cfm is not the final cfm; additional adjustment may be required for Altitude. See next item- Cooling Fan.
Cooling Fan
Software used to perform the calculation will typically provide a minimum cfm based on the minimum required size of the equipment. This number may be adjusted to meet specific requirements of the home. Heating and Cooling CFM may or may not be the same. The cooling CFM should be around 450 CFM per ton of cooling in Utah’s dry climates. For higher altitudes, CFM must be adjust up as detailed in ACCA / ANSI Manual S. Mountain location should expect Cooling CFM at 500 CFM per ton and higher.
HEATING
Equipment
List specific equipment to be used. This information is not required on the Load Calculation documents, however it must be provided here to verify equipment sizing against calculated loads.
The AFUE (Annual Fuel Utilization Efficiency) listed here will be compared to that listed on plans and on energy compliance documents (RES check or other). It must also match the equipment actually installed in the home.
Sea Level Input
The listed input on the furnace label and in manufacturers’ documentation. Input represents the total amount
of heat in the gas at sea level.
The amount a heat available for discharge into the conditioned space. The input less any vent or stack losses, or heat that is carried out with the products of combustion. May be take from manufacturer’s performance data or calculated using input and furnace efficiency.
Altitude Adjusted Output
This number is the actual output that will be attained after the furnace has been adjusted for efficiency and de-rated for altitude (typically 4% for every 1000’ above sea-level, however 2% /1000’ for many 90+ efficient furnaces). Some manufacturers may have different requirements- adjustments should be made per their requirements. Calculations should be attached. Example: 80,000 input 91% efficient furnace in Salt Lake, with manufacturers’ installation instructions specifying 4% / 1000’. 80,000 x .91 x .83 = 60,424 btuh.
Multi-Stage Furnace
Multi-stage and modulating equipment is now available. When comparing to heating load calculated, use the maximum adjusted output to verify the furnace is large enough and the lowest output to insure it is not too large.
Size Justification
Example: If the Total Heating Load = 29954 btuh. A furnace with an adjusted output larger than 45,000 btuh (29954 x 1.5 = 44931) would require an explanation justifying the size.
COOLING
List specific equipment to be used. Provide manufacturers comprehensive data for furnace, furnace blower and condenser, with capacities at design conditions highlighted.
Condenser SEER
This SEER (Seasonal Energy Efficiency Ratio) is the listed SEER for this model series, not the exact SEER with components used this system.
Total Capacity
Manufacturers base data is based on ARI Standard 210 / 240 ratings; 95 °f outdoor air temperature, 80 °f db / 67 °f wb entering evaporator. As the Design Conditions
are different than this standard, refer to manufacturers expanded ratings for capacities at actual design conditions. Total capacity is the latent and sensible capacity at design conditions
Sensible Capacity
The sensible only capacity from the manufacturer’s expanded data at design conditions.
Manual D Calculations & Summary
Friction Rate Worksheet & Steps
1Manufacturer’s Blower Data
External static pressure (ESP)
IWC
Latent Capacity
The latent only capacity from the manufacturer’s expanded data at design conditions. NOTE: One half of the excess latent capacity may be added to the sensible capacity.
Evaporator Coil Make and Model #
List the exact model number for the evaporator coil used this system. If coil is from a different manufacturer than the condenser is used, provide data from both manufacturers verifying actual performance.
Expansion / Metering
Provide the specific metering used- orifice or TXV (thermostat expansion valve). If the manufacturer has several options, list the option used.
Actual SEER Rating
Attach manufacturers’ documentation or ARI report showing actual cooling capacity, and actual SEER using the components used this system. Indoor air handler / furnace blower must be included in this documentation. Do not use ARI (ARHI) data for actual sizing.
If cooling capacity is 15% greater than the calculated Cooling load explain. High latent (moisture) loads can be listed here. Special requirements particular to the customer may also be noted here.
2Device Pressure Losses
Evaporator
Supply register
.03
Other device
Air filter
Return grill
Total device losses (DPL)
3Available Static Pressure (ASP)
ASP = ( ESP - DPL ) IWC
4Total Effective Length (TEL)
Supply side TEL
Return side TEL
Total effective length (TEL) = supply side TEL + return side TEL ft
5Friction Rate Design Value (FR)
FR = ( ( 100 x ASP ) / TEL ) IWX / 100’
Mechanical Sizing
Name of contractor / designer
Phone Fax
Address
Permit # Lot #
This friction rate (FR) calculated in Step 5 is the rate to be used with a duct calculator or a friction chart for the duct design on this project.
Attach at a minimum, a one line diagram showing the duct system with fittings, sizes, equivalent lengths through fitting and duct lengths.
Vent height (base of duct to roof exit) ft
Boiler or furnace input rating
btu
De-rated input rating (use .83)
Connector rise
Connector run
Connector size
in
Orifice size
Water heater input rating
De-rated input rating (.83 minimum)
Total heat input of all appliances
Vent size for the system
Combustion air size
in²
Signature
Boiler or furnace #2 input rating btu
De-rated input rating (use .83) btu
Connector rise ft
Connector run ft
Connector size in
Orifice size in
Water heater #2 input rating btu
De-rated input rating (.83 minimum) btu
Attach a complete gas pipe layout & sizing detail to the plan or permit application.
If a manifold is used to connect the appliances on the horizontal, it shall be the same size as the vent.
To the best of my knowledge, I certify that the information contained within this document is true, correct, and meets the requirements of the 2009 International Mechanical Code and International Fuel Gas Code.
Date
Mechanical Sizing Worksheet
b
Example: SLC has a 17% de-ration
How-To
factor. On a 100,000 Btu furnace you
Materials needed to fill out this form are the
multiply 100,000 x .83 = 83,000 Btu’s
c
On the vent sizing this becomes
International fuel gas Code and the Questar
Recommended Good Practices Book.
the fan min. The fan max is the
VENT SIZING
listed input rate example fan
min = 83 and fan max = 100
1
Vent height is measured from the
d
The Btu to ft³ conversion number for
draft diverter or appliance vent
SLC is 890 and the specific gravity of
outlet to the top of the vent cap.
the gas is .60. Divide the new input
2
Connector rise is the height of the vent
rating by 890, 83,000 = 93.258 ft³. 890
connector from the appliance outlet
e
Take the ft³ of input and divide it by the
to the center of the tee in the vent at
number of burners on the appliance,
the point of connection to the vent.
this will give you the ft³ / burner. Then
3
Connector run is the horizontal distance
use the orifice tables in the Questar
handbook to determine the orifice size.
from the appliance vent outlet to the vent.
Example if you have 4 burners: 93.258
4
Go to the International Fuel Gas
ft³ / 4 burners = 23.315 ft³ / 1 burner.
Code Chapter 5. Sizing is done to
Match as close as possible to the
the appropriate gamma table .
Orifice table in the handbook. In this
5
The gamma tables are in Btu and not ft³
sample the orifice size would be (49)
Use the International Fuel Gas Code and the
DE-RATING
International Mechanical Code to complete
See Questar handbook for a step-by-step
the vent sizing and the combustion air
sizing. See Chapter 5 IFC for the rules and
formula and the required conversion
the tables to fill out this portion of the form.
numbers. To complete this form:
ICBO also has available a commentary on
a Input is de-rated at 4% per
the mechanical code that contains a step-
1000’ in elevation.
by-step examples of how to size the vents.
3The International Mechanical Code commentary also contains examples to size the gas pipe. You must show the pipe lengths, the Btus and the volume of each appliance and show the size of each length of pipe. All tables necessary to size gas pipe are also contained in the International Fuel Gas Code, and in the Questar handbook.
4For Salt Lake City use:
a890 Btu per ft³
bA multiplier of .83
cSpecific gravity of .60
dCombustion air is computed at 1 in² per 3,000 Btu of input of all fuel burning appliances in the room. One duct upper 12” of the room.
EQuestar gas has a training program available to all persons and contractors.
Filling out the Manual J form requires careful attention to detail, as the information collected will help ensure that the heating and cooling systems in a building are appropriately sized. Following these steps will guide you through the process of completing the form accurately.
The Manual J form is a worksheet used for calculating heating and cooling loads for residential HVAC systems. It helps ensure that heating and cooling equipment is appropriately sized for the specific needs of a home, taking into account various factors such as climate, building materials, and insulation levels.
A Manual J calculation is essential because it provides a detailed analysis of the heating and cooling requirements of a home. Properly sizing HVAC equipment based on these calculations helps improve energy efficiency, enhances comfort, and prevents issues like short cycling or inadequate heating and cooling.
To fill out the Manual J form, start by entering project information such as the location, design conditions, and specific equipment details. You'll need to assess factors like outside and inside temperatures, infiltration rates, and any unique characteristics of the home. Each section of the form corresponds to different aspects of the load calculation, and accurate data is crucial for reliable results.
Several factors influence heating and cooling loads, including:
No, the Manual J form provided is specifically designed for homes built in Utah’s dry climate. Using it in other climate conditions may yield inaccurate results. Always ensure that the load calculation method is appropriate for your specific location.
Manual J focuses on calculating the heating and cooling loads, while Manual D is used for duct design and sizing. The load calculations from Manual J are essential for ensuring that the ductwork, as outlined in Manual D, is properly sized to deliver the calculated heating and cooling efficiently.
A Manual J calculation should be performed whenever a new HVAC system is installed or an existing system is replaced. It is also advisable to conduct a new calculation if significant changes are made to the home, such as renovations or additions, that could impact the heating and cooling loads.
If the Manual J calculations are incorrect, it can lead to several issues, including:
For assistance with the Manual J form, consider reaching out to a licensed HVAC professional or contractor. They have the expertise to guide you through the process and ensure that your calculations are accurate and compliant with local codes.
Filling out the Manual J form is a critical step in ensuring your HVAC system is properly sized for your home. However, many people make mistakes during this process that can lead to inefficiencies and increased costs. Here are seven common mistakes to watch out for.
One frequent error is failing to provide accurate design conditions. This includes both heating and cooling temperatures, which should be based on the local climate. If the temperatures used do not match those listed in the Manual J guidelines, it’s essential to explain why different values were chosen. Neglecting to justify these adjustments can lead to incorrect load calculations.
Another mistake involves the infiltration method. Many individuals overlook the importance of accurately assessing the construction quality of their home. The infiltration rate can vary significantly based on whether a home is classified as tight, average, or loose. Using the wrong method or failing to note the method used can result in improper heating and cooling load estimates.
People often forget to include all heat loss factors in their calculations. This includes not just the building components but also losses through infiltration, ventilation, and duct losses. Every factor contributes to the overall load, and missing even one can skew the results significantly.
In addition, many individuals do not take into account the temperature rise range specified by the equipment manufacturer. Heating airflow should be adjusted to ensure that the temperature rise across the heat exchanger falls within this range. Ignoring this can lead to inadequate heating performance and potential equipment damage.
Another common oversight is the cooling CFM calculation. Many people assume that the cooling airflow will be the same as heating airflow, which is often not the case. Adjustments may be necessary based on specific requirements for the home, especially in higher altitudes. This miscalculation can lead to inefficient cooling and increased energy costs.
Furthermore, individuals frequently neglect to provide justifications for equipment sizing. If the selected heating or cooling equipment has a capacity greater than 1.5 times the calculated load, it’s crucial to explain why. Failing to do so may raise red flags during inspections and can lead to compliance issues.
Lastly, not attaching manufacturer’s documentation can be a significant error. Documentation showing actual performance data for the equipment used is essential for verifying that the system is appropriately sized. Without this information, it can be challenging to ensure compliance with local codes and standards.
By being aware of these common mistakes, you can improve the accuracy of your Manual J form and ensure that your HVAC system operates efficiently and effectively.
The Manual J form is essential for calculating heating and cooling loads in residential buildings. However, several other documents complement this form to ensure a comprehensive understanding of HVAC requirements. Below is a list of these documents, each serving a unique purpose in the HVAC design process.
Utilizing these documents in conjunction with the Manual J form ensures a thorough approach to HVAC design. Each form plays a vital role in achieving an efficient and effective heating and cooling system for residential properties.
The Manual J form is an important document used for calculating heating and cooling loads in residential buildings. Several other documents serve similar purposes in various aspects of HVAC design and energy efficiency. Here are seven documents that share similarities with the Manual J form:
When completing the Manual J form, it is essential to approach the task with care and attention to detail. Below are four recommendations that can guide you in this process, highlighting both what to do and what to avoid.
By following these guidelines, you can help ensure that the Manual J form is completed correctly, ultimately contributing to a more effective heating and cooling system design.
Misconceptions about the Manual J Form
This is incorrect. The Manual J form is specifically developed for homes built in Utah's dry climates. Using it in other conditions may yield inaccurate results.
In reality, performing Manual J calculations is mandatory for accurate HVAC system sizing. These calculations ensure that heating and cooling loads are correctly assessed.
This is a misunderstanding. The Manual J form calculates both heating and cooling loads, including sensible and latent gains, to provide a comprehensive assessment of a home's climate control needs.
Not all software is equipped to handle the specific requirements of Manual J. It is crucial to use software that adheres to the guidelines set forth in the ACCA Manual J.
This is false. Infiltration is a critical factor in the calculations. It must be evaluated based on construction quality and included in the load assessment.
This is misleading. The Manual J form can also be utilized for existing homes undergoing renovations or upgrades to ensure that the HVAC system is properly sized for current conditions.
Understanding the Manual J form is essential for accurate HVAC load calculations. Here are some key takeaways to consider:
By keeping these points in mind, you can effectively navigate the Manual J form and ensure your HVAC system is designed for optimal performance.