ONE: You must determine how much heating and/or cooling energy your home will require. This determines how much energy needs to be generated and transferred into the forced air for distribution throughout your home to heat and cool your home comfortably and efficiently.
The only way to do this is to properly complete a well recognized and accepted heat loss (heating) and gain (for cooling) calculation for the project. This must be done by the installer selecting and installing the equipment or provided to him by a recognized professional or service. You must receive a copy of this for your records.
Without this calculation your installer cannot prove that he proceeded based upon accurate information to design and install your system or systems.
If your installer has any problems whatsoever with the performance of the systems he installs in your project, the very first question that will be asked by the manufacturers, licensed professional (such as engineers and architects), third party examiners (arbitrators), local regulatory agency officials, and any legal counsel will be "What did the heat loss and gain calculation determine was the requirement for this project?".
TWO: Once your installer understands how much energy must be provided to heat and cool your home, the installer can then select the properly sized equipment from the manufacturer he, and hopefully you, have selected. This selection must be based upon the sizing and selection guidelines provided by that manufacturer. The manufacturer designs the equipment based upon the scientific fact that air has a capacity, at any stated temperature, to hold energy. The equipment sizing is stated in clear terms to allow the proper selection of equipment based upon the requirements determined by the properly completed heat loss and/or gain calculations.
The heating and cooling energy generators (described below) and the air handler(s) must be selected to meet the requirements of the heat loss and/or gain calculation and the manufacturers stated guidelines for selection, application, and installation.
These equipment selections must be made to match your needs as closely as possible and be compatible with all equipment selections working together to heat and cool your home to operate properly and efficiently. If the wrong pieces of equipment are selected they will not properly heat and cool your home.
The Air Handler contains a blower and passive coils or radiators. It is the most important piece in the SDHV air distribution system. It is the place that the heating and cooling energy generated by a boiler, condenser, heat pump or chiller is transferred to, or from, the air being pushed through the system by the blower. Its capacity is most commonly stated in cooling tons (a cooling ton equals 12,000 BTUs), heating BTUs, Total Air Flow Capacity (such as 600 CFM), Main Voltage supply required (such as 230/1/60), and Amp Draw (how much energy it uses under load).
THREE: The most common performance failure for any type of forced air system is improper supply duct design and installation. It is unnecessary because the primary duct system or the larger main duct in the SDHV) is designed with and constructed of commonly available sheet metal or fiberglass ducting.
This is the least expensive part of your system and yet it is the most common reason these system are installed properly.
The primary (larger main) supply duct design must be properly designed and sized to carry the capacity of conditioned air provided by the air handler. If the primary duct design is undersized, or restricted, the system cannot perform properly.
The first rule in all duct design is to maximize primary supply and minimize secondary (smaller) supply ducting. The SDHV Systems have the simplest design requirements and smallest size ducts of any forced air system. They should be easier to size, design, and install in your home than other forced air systems.
The design and installation of the SDHV primary supply duct system should be completed to insure a high quality, airtight, properly sealed and insulated duct system capable of distributed the volume of air delivered by the air handler installed.
Duct installers and sub contractors in many regions are the least appreciated and most competitively shopped sub contractors in the equation. It has always startled us that this work always went to the lowest bidder with the cheapest price and, sometimes, the most questionable labor and practices. The primary supply duct design and installation is an important cornerstone of the performance of the system. If your installer maintains employees on staff to install these duct systems it is an advantage, if they are properly instructed and managed.
If any of the first three steps described here are not done as stated and prove to be incorrectly designed, sized, selected or installed and the performance of the equipment is not satisfactory, the manufacturers are not responsible for the lack of performance and should not be asked to participate in the repairs.
Repairs that are necessary due to any failures in the first three steps can be extremely costly and difficult to resolve. The best practice is to follow these steps to make sure you are properly protected.
FOUR: We have a good approach to the Secondary Supply Ducts and Supply Air Outlets which are designed and manufactured specifically to meet the needs of the SDHV air handlers and provide the proper volume, speed, sound attenuation and aspiration benefits that are all part of the SDHV Systems.
This approach will be questioned in certain regions, by certain installers and in certain competitive markets. These installers will state that they can use fewer outlets than our approach demands thereby resulting in a lower cost to the homeowner and a more competitive price.
We do not disagree.
If the installer has followed the first three steps described here and can design and install fewer outlets and meet both, the performance requirements in your home and achieve a level of quiet operation acceptable to you, then it may be an acceptable practice. We believe the homeowner must be informed and be a part of that decision.
We believe that the best method for specifying the number of the manufacturers secondary air supply lines and air supply outlets (in all but the rarest applications) is to divide the air volume capacity of the air handler by a number ranging from 32 to 34 to determine how many secondary air supply lines and air supply outlets must be installed. The numbers used represent the optimum minimum CFM at each air supply outlet for most applications for quiet and efficient operation. The installer should determine this number of supply outlets and recognize that he should design and provide this number in his estimate. Any secondary supply lines that must be extended beyond normal length will exhibit reduced air flow and must be adjusted accordingly. In extremely rare instances additional secondary air supply lines and air supply outlets may be necessary.
The proprietary secondary air supply lines and air supply outlets must be installed with good airtight connections with good air supply paths to the air supply outlet. They must be properly strapped in place.
The practice of using a minimum number of air supply outlets per ton, while it may be correct, unintentionally provides the installer who has found it necessary to cut his costs evidence to justify this practice to the homeowner and more often reduces the performance of the equipment supplied and subjects the homeowner to noisy operation of the equipment.
If the first three steps as described here are followed correctly, any secondary supply issues should be reasonable to accomplish to insure that your systems are properly installed and operate efficiently. A correctly conducted performance evaluation (which is necessary for most manufacturers warranty registration) will easily identify the adjustments necessary.
FIVE: The final main component for a successful SDHV System installation is a properly designed and installed return air path or return air ducting.
If you have properly designed the primary and secondary air supply ducting there will be no restriction to air flow on the supply side of the system. You must now allow enough air to come back from the conditioned space, be filtered (thus the importance of clean filters) and continue through the air handler to conditioned again for distribution by the supply side of the system.
Each air handler has a stated volume of air that it will move through the heating and/or cooling coils. Refrigerant cooling coils are most sensitive to insufficient air flow and may ice up. This will affect the cooling performance. Hot Water heating coils are generally less sensitive to air flow.
The manufacturers clearly state the volume of return air required to serve each size air handler. The return air path or duct must consider all factors including, but not limited to, return grill type and placement, duct material, overall length, filter accessibility (and ease of servicing), and the prevention of blockage by household items to work properly. Although each manufacturer sells very basic standard components that will work properly with each air handler, they are often not usable in many applications and the return air duct must be designed and built to suit the needs of your home. These customized return air paths must be designed and installed to meet the needs of the air handler as stated by the manufacturer.
We have found that it is always a part of the challenge in any forced air system to design and install an acceptable return air path meeting all parties' needs. It is seen by many homeowners as the largest visible change within their home and the homeowners' reaction may place unfair limits on the installers' intentions.
Everyone must accept that a properly sized return air path is a necessary technical requirement for proper operation and must be accommodated.
It is possible for many installers to design and install multiple smaller return grill openings that in total will meet the manufacturer's requirements and be visually more appealing to the homeowner but expect that this will add measurably to the cost and complexity of the project. It is better to be generous in your return air path or ducting rather than to compromise. A compromised return air path will be intolerant of clogged or dirty filters and filtering systems.
SIX: The last step is to insure that the installer has tested and verified that the equipment is operating properly.
You must confirm that the testing has been documented by requesting a copy. The documented results must be filed with the manufacture to provide you the manufacturers stated warranty protection. This completes the installation. It is not an optional step and must be specified as a component of the installation and the payment schedule to insure it occurs. Our clients send these testing documents to High Velocity Helper and we insure that they are properly filed.
The installer must accurately measure the performance of the equipment as specified in the manufacturers written installation guidelines. These results must be provided to the manufacturer to insure that the installation of their equipment meets their application and installation guidelines and will provide the homeowner proper performance and good service life. In most cases this is required for your SDHV System to receive the manufacturer's standard, or extended, warranty protection.
The performance testing and warranty registration is one of the most overlooked steps in an SDHV System installation and, we suspect, in all forced air heating and cooling equipment installations. When we check with the manufacturers, we find most often, that this is left undone by the installer and forgotten. We ask "How do you know if it is working properly, if you do not check?" The other question is "Do you have the manufacturers stated warranty protection?"
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