Manual S ensures YOUR heating and cooling equipment is properly sized and will maintain the required design comfort conditions calculated by ACCA Manual J. Also ACCA Manual S verifies the HVAC has enough blower power to move the required amount of air (CFM) through the duct system. An understanding of how to interpret the manufacturers equipment (OEM) data is essential to correct HVAC sizing.
WrightSoft Version 6 HVAC Duct System Design and Heat Load Loss Serial Key
Several items from the Manual S are used in the Manual D duct design. The heating mode looks at the temperature rise requirement (Manual S section 2-6) while the cooling load looks at the air flow (CFM) associated with the selected equipment's capacity (Manual S section 3-11).
Chvac quickly and accurately calculates the maximum heating and cooling loads for commercial buildings. The cooling loads can be calculated with either the CLTD method or the new RTS (Radiant Time Series) method. The program allows an unlimited number of rooms which can be grouped into as many as 100 air handling systems. Chvac automatically looks up all cooling load and correction factors necessary for computing loads. In addition, it can look up outdoor design weather data for over 2000 cities located around the world. There is also provision for editing the weather data as well as adding data for other cities. Comprehensive reports list the general project data, detailed room loads, air handler summary loads, outside air loads, total building loads, building envelope analysis, tonnage requirements, CFM air quantities, chilled water flow rates (if applicable), and complete psychrometric data with entering and leaving coil conditions. Other outstanding features include ASHRAE Standard 62 analysis, automatic building rotation, 360 degree wall orientations, tilted glass, exterior shading, internal operating load profiles, variable indoor design temperatures, people diversity, pretreated outside air, seasonal infiltration and ventilation rates, reheat loads, duct gains and losses, and return air plenums.
There are five versions of the Chvac program; 2 room capacity ($299), 10 room capacity ($399), 50 room capacity ($599), 100 room capacity ($999), and unlimited capacity ($1499). Keep in mind that a room is a single space, and that rooms can be grouped into air handling systems which in turn make up the building. Rooms can optionally be grouped under vav boxes as well (zones). This allows Chvac to compute diversified peak loads at four levels in one run of the program: room, vav box (zone), air system, and total building. The maximum number of air handling systems allowed for any version is the number of rooms allowed or 100, whichever is the lesser. Each Chvac version is exactly the same with the exception of the room capacity and price. However, there is a generous upgrade policy. If at any time you decide to obtain a version of Chvac with greater capacity than the original one you obtained, all that is required is to pay the difference in price between the two versions.
Five types of data are requested: general project data, outdoor design data, building material data, air handler data, and specific room data. The general project data includes the project and client name, designer, building opening and closing hours, internal operating load schedules, and any desired safety factors. The outdoor design data includes the summer and winter outdoor design conditions (automatically looked up for you if a city reference is given) and the desired ventilation and infiltration rates. The building material data includes the definition of master building material types for roofs, walls, partitions, glass sections, and exterior shading. A user defined material library is available for saving the data on common material types. The air handler data includes the fan and terminal type, the desired heating and cooling supply air temperatures and data for duct heat gains and losses. The room data includes the room name, floor length and width, number of people, equipment watts, lighting watts, external shading data, and specific roof, wall, partition, floor and glass data.
Central, "all-air" air-conditioning systems (or package systems) with a combined outdoor condenser/evaporator unit are often installed in North American residences, offices, and public buildings, but are difficult to retrofit (install in a building that was not designed to receive it) because of the bulky air ducts required.[23] (Minisplit ductless systems are used in these situations.) Outside of North America, packaged systems are only used in limited applications involving large indoor space such as stadiums, theatres or exhibition halls.
The performance of vapor compression refrigeration cycles is limited by thermodynamics.[30] These air conditioning and heat pump devices move heat rather than convert it from one form to another, so thermal efficiencies do not appropriately describe the performance of these devices. The Coefficient of performance (COP) measures performance, but this dimensionless measure has not been adopted. Instead, the Energy Efficiency Ratio (EER) has traditionally been used to characterize the performance of many HVAC systems. EER is the Energy Efficiency Ratio based on a 35 C (95 F) outdoor temperature. To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER, the Seasonal Energy Efficiency Ratio (SEER), or in Europe the ESEER, is used. SEER ratings are based on seasonal temperature averages instead of a constant 35 C (95 F) outdoor temperature. The current industry minimum SEER rating is 14 SEER.[31] Engineers have pointed out some areas where efficiency of the existing hardware could be improved. For example, the fan blades used to move the air are usually stamped from sheet metal, an economical method of manufacture, but as a result they are not aerodynamically efficient. A well-designed blade could reduce the electrical power required to move the air by a third.[32]
Aside from current and pending building code changes in some markets requiring ducts to be in conditioned space, doing so simply makes sense. Attics experience significant temperature extremes in the summer and winter (hot and humid or extremely cold) affecting how effectively a duct in the attic can deliver conditioned air at the right temperature. The result is a system that has to run longer to heat or cool a room due to the significant amounts of energy loss along each insulated duct run. In addition, the risk of condensation in areas where duct insulation r-value is compromised, such as at the register boot, hanging straps, and areas where ducts are pinched or kinked also negatively impact the efficiency of the duct. Moving ducts into conditioned spaces resolves these issues.
Rheia will not change the heating and cooling equipment installed in the home. Manual J heat load calculations will still be performed, and Manual S equipment selections will still be used. Rheia systems are approved for all climate types. In cold climates, the heating equipment is responsible for maintaining minimum temperatures. In hot climates, the cooling equipment is responsible for maintaining maximum temperatures. In humid climates, the cooling and optional dehumidifying equipment is responsible for humidity control. Properly sized equipment is the key for temperature and humidity control. The duct system is responsible for distributing the air throughout the home proportionally to the heat load. Rheia does this through the design and commissioning processes.
I second the notion that finding HVAC contractors who'll actually do the work of good load calculation and system design has been a challenge. I earned a degree in mechanical engineering from a local technical institute many years ago but have spent my career in the manufacturing segments of industry. I'm willing to dust off my old heat transfer classwork and do the Manual J calculations myself like you. Can you disclose what software you wound up using and if you'd recommend it to others like myself? I've used coolcalc.com and found it reasonably sophisticated in terms of number of details it asked for. It took me the better part of an hour to get through that process but it came up with a cooling load that was much lower than I would have ever expected (under 3 tons total).
As alluded to above, I'm also planning to invest in making the house more airtight and higher levels of insulation as time goes by. So I'd love to have a software package that allows me to play with those various scenarios to see their ultimate impact on overall cooling and heating load. I'd rather design and purchase this system that will hopefully last me 12-15 years with the end goal in mind, even if that means in the initial years of the system's operation it struggles on more than a few hotter days here in the Atlanta sweltering summers. Then as I make those improvements, the house "catches up" to the smaller sized systems.
Manual D works in conjunction with the other manuals to provide proper design, sizing, and installation of residential duct systems. After you have determined the heating and cooling loads (Manual J), selected the right HVAC equipment (Manual S), and figured out how to distribute the air (Manual T), you can now design the duct system (Manual D). 2ff7e9595c
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