13 SEER UNIT ISSUES: 
          

NEW CONSTRUCTION JOBS

The larger 13 SEER products occupy more space outside as well as in closets, attics, crawl spaces, and the mechanical areas in basements used for the indoor part of a split unitary system. Contractors need to consult with local builders and urge adjustment of floor plan drawings to allow for ample space for adequately-sized systems.

The best solution is for Contractors to work closely with local builders and zoning officials to ensure their full understanding of the space required to satisfy the US DOE and Canadian NRC minimum efficiency standard.

REPLACEMENT OR RETROFIT JOBS

In replacement situations where an exisiting structure does not have adequate space for a new larger coil and air handler, consider the following:

• The existing indoor coil may be acceptable if it is fitted with a TXV valve and the system is a straight cool system. However, reduced capacity is likely.

• Old fixed restrictor coils will not perform properly with a new minimum standards 13-SEER or higher outdoor unit. Check with an authorized Ruud Distributor to see if a TXV kit is available for the indoor coil. If so, it may be possible to convert the old coil to one that may be acceptable for use with a new 13-SEER straight-cool-only outdoor unit.

• Under no circumstance should a new 13-SEER heat pump unit be matched with the old indoor coil unless the original equipment manufacturer specifically lists the old coil model as an acceptable coil match for that specific outdoor model.

FOR MORE INFORMATION ; See: "Federal Requirments for Appliances " by clicking on page to your  right....

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Residential Flex Ducts:

Like any other listed construction product, flex duct should be installed according to the terms of its listing and according to manufacturer's instructions. The following guidelines apply to most flexible duct systems.

1.  Avoid bending flex duct across or around framing members, pipes and other objects. Such bends can decrease the size of the duct at the bend point, restricting airflow and increasing air friction. Over time, the duct inner core can continue to collapse at the bend point further restricting airflow. This is a common installation error.

2.  Avoid bending flex duct so that the radius at the centerline is less than one duct diameter. Such bends also restrict airflow and increase air friction. This is another common installation error.

3.  Run flex duct through spaces at least as large as the diameter of the duct inner core. While this might seem a statement of the obvious, compressing flex ducts is a common installation error. The ducts are often compressed to fit into small spaces, such as chases running between floors and the area between truss webs and truss braces in floors and attics. This installation error is also frequently found when ducts are run between different areas, such as between a garage attic and the attic over the conditioned area. Minor compression of the duct is acceptable so long as the inner core is not compressed.

4.  Support flex duct horizontally at intervals of not more than 5 feet and vertically at intervals of not more than 6 feet. The maximum amount of sag between supports is 1/2 inch per foot of horizontal run. Support plenums and distribution junctions independently of the flex duct. Support straps or other support material should be at least 1 1/2  inches wide. Support by lumber is usually acceptable.

5.  Avoid using flex duct to support other flex duct or construction materials such as wires or coolant lines. Over time, the weight of these materials can constrict the duct inner core.

6.  Extend flex duct to its full length. Excess duct material in a run should be less than 5 percent. Excess material increases air friction.

7.  Run flex duct out of plenums, distribution junctions and boots at least 12 inches before making a bend in the duct. Tight bends near plenums also increase air friction and decrease duct size.

8.  Provide air space on all sides of flex duct when the duct runs through unconditioned spaces such as attics and crawlspaces. Avoid fully or partially covering flex duct with insulation. This is more important in humid climates than in dryer climates. Moisture can condense on flex duct that does not have adequate airflow around it. This moisture can damage surrounding materials and can contribute to fungal growth.

9.  Provide clearance between flex duct and furnace or water heater vent flues as required by the flue type. Flex duct is considered to be combustible material in terms of clearance to combustion appliances flues.

10.  Avoid running flex duct over steam pipes and similar heat sources.

11.  Install flex duct at least 4 inches above ground level and above the design flood elevation. Do not install flex duct in tile, metal pipe or within masonry or concrete.

12.  Avoid installing flex duct where it will be subjected to direct sunlight, such as under turbine vents. Sunlight can degrade the vapor barrier.

13.  Attach flex ducts at plenums and distribution junctions to sheet metal collars that are at least 2 inches long. Use metal sleeves at least 4 inches long to splice two lengths of flex duct. Make joints substantially airtight. Use at least two wraps of approved metal tape to attach the duct inner core at collars and distribution junctions. A clamp is recommended, though not always required. Use both tape and clamps to splice two lengths of flex duct.

14.  Repair tears in the vapor barrier using recommended material.

15.  Install fireblocking where flex duct penetrates floor and ceiling assemblies, and where it penetrates concealed connections between vertical and horizontal spaces such as soffits and other dropped ceilings. Unfaced batt mineral wool or fiberglass insulation is usually acceptable fireblocking material.

16.  Avoid installing flex duct that penetrates a fire-rated assembly unless approved by the authority having jurisdiction. This includes flex duct connected to boots located in a garage.

17.  Protect flex duct from damage by sharp objects such as truss gusset plates, attic furnace support straps and nails. These objects can puncture the duct.

18.  Protect flex duct from moisture during and after construction. Once it becomes wet, flex duct insulation can remain wet for years, providing a breeding ground for fungal growth.

19.  Protect duct boots, particularly floor ducts, from contamination during and after construction.

                                         Common Residential Code Violations

Prohibited locations. Fuel-fired appliances shall not be located in, or obtain combustion air from, any of the following rooms or spaces:
 1. Sleeping rooms.
 2. Bathrooms.
 3. Toilet rooms.
 4. Storage closets.
 5. Surgical rooms.

    Elevation of ignition source. Equipment and appliances having an ignition source and located in hazardous locations and public garages, private garages, repair garages, automotive service stations and parking garages shall be elevated such that the source of ignition is not less than 18 inches (457 mm) above the floor surface on which the equipment or

  appliance rests.

  Clearances from grade. Equipment and appliances installed at grade level shall be supported on a level concrete slab or other approved material extending above adjoining grade or shall be suspended a minimum of 6 inches (152 mm) above adjoining grade.

 Electrical requirements. A lighting fixture controlled by a switch located at the required passageway opening and a receptacl outlet shall be provided at or near the appliance location in accordance with the code.

 Appliances in attics. Attics containing appliances requiring access shall be provided with an opening and unobstructed passageway large enough to allow removal of the largest appliance.  The passageway shall not be less than 30 inches (762 mm) high and 22 inches (559 mm) wide and not more than 20 feet (6096 mm) in length measured along the centerline of the passageway from the opening to the appliance.  The

  passageway shall have continuous solid flooring not less than 24 inches

  (610 mm) wide.  A level service space not less than 30 inches (762 mm)

  deep and 30 inches (762 mm) wide shall be present at the front or service side of the appliance.  The clear access opening dimensions shall be a minimum of 20 inches by 30 inches (508 mm by 762 mm), where such dimensions are large enough to allow removal of the largest appliance.

 Clothes dryers shall be exhausted in accordance

  with the manufacturer's instructions.  Dryer exhaust systems shall be

  independent of all other systems and shall convey the moisture and any

  products of combustion to the outside of the building.

Attic Access requirements
   a.Clear and Unobstrcued

   b.Allow removal of largest piece

   c.Max. dist. Is 20 feet to unit

   d.Floored access 24-inches wide to unit

    e.30x30 inch service area on panel side

     f.Lighting required and receptacle outlet

 Under Floor:

    a.Lighting and outlet required

    b.Equip. suspended must maintain 6-in. ground clearance

 Ground Support : “ Appliance supported from the ground shall be level and firmly supported on a concrete slab or other approved material…”   Heat pump equipment outdoors shall be 3-inches above the ground …”

Equipment disconnect: : Disconnecting means are permitted to be installed on or within    sight (50-ft) of unit. Access to disconnect shall comply with 30” clear space access requirements  of the code.

Drain:: Condensate from all cooling coils shall be conveyed from the drain pan outlet to an approved place of disposal.” “ Auxillary and secondary system. In addition to ¾-inch drain to a conspicuous location ( over window /door) ….may use water level detection device as an alternative……”

Duct Design. Duct systems serving heating, cooling and ventilation equipment shall be fabricated in accordance with the provisions of this section and ACCA Manual D or other approved methods:

COMMON VIOLATONS:

1.       Duct clearance :  : Ducts shall be installed with at least 4-inches separation from earth…”

2.       Support:
a.       Metal- 0.5-inch wide 18-gaug metal straps or 12-gauge galv. Wire at intervals not to exceed 12-feet
b.       Nonmetallic ducts (flex) – per manufacturer’s requirements

3.       Sealing duct connections at floor boots and registars: : Joints of duct systems shall be made substantially airtight by means of tapes, mastics, gasketing or other approved means.

Other: 

1.       Openings in masonry foundation walls for equipment and/or return/supply ducts not supported by lintels per IRC ” Masonry over openings shall be supported by steel lintels, reinforced concrete or masonry lintels or masonry arches, designed to support load imposed.

2.       Cutting & Notching of framing members shall comply with the code.

The Air Conditioning Contractors of America’s (ACCA) Manual J, Residential Load Calculations, is the accepted industry standard, approved by the American National Standards Institute, for the proper sizing and selection of HVAC equipment in residential homes.
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FABRICATE AND INSTALL AN AIRTIGHT DUCT SYSTEM

All Duct Types

• All joints and seams of duct systems and their components should be sealed with mastic, mastic and embedded mesh, or pressure-sensitive tape approved for use by the duct manufacturer and meeting UL181 specifications ("approved tape"); this includes around junctions of collars to distribution boxes and plenums;

• All sealants should be used in strict accordance with manufacturer's installation instructions and within sealants moisture and temperature limitations;

• All tapes used as part of duct system installation should be applied to clean, dry surfaces and sealed with manufacturer's recommended amount of pressure or heat. If oil is present, taped surfaces should be prepared with a cleaner / degreaser prior to application;

• It is recommended that all register boxes should be sealed to the drywall or floor with caulking or mastic.

Flexible Ducts

• 
• Flexible ducts should be joined by a metal sleeve, collar, coupling, or coupling system. At least 2 inches of the beaded sleeve, collar, or coupling must extend into the inner core while allowing a 1 inch attachment area on the sleeve, collar, or coupling for the application of tape;

• The inner core should be mechanically fastened to all fittings, preferably using drawbands installed directly over the inner core and beaded fitting. If beaded sleeves and collars are not used, then the inner core should be fastened to the fitting using #8 screws equally spaced around the diameter of the duct, and installed to capture the wire coil of the inner liner (3 screws for ducts up to 12" diameter, and 5 screws for ducts over 12" diameter);

• The inner core should be sealed to the fitting with mastic or approved tape;

• Tape used for sealing the inner core should be applied with at least 1 inch of tape on the duct lining, 1 inch of tape on the fitting of flange, and wrapped at least three times;

• The outer sleeve (vapor barrier) should be sealed at connections with a drawband and/or three wraps of approved tape;

• The vapor barrier should be complete. All holes, rips, and seams must be sealed with mastic or approved tape.

Metal Ducts and Plenums

• Metal-to-metal connections should be cleaned and sealed in accordance with manufacturer's specifications;

• Openings greater than 1/16 inch should be sealed with mastic and mesh, or butyl adhesive tape;

• Openings less than 1/16 inch should be sealed with mastic or UL-181A listed tape;

• Special attention should be paid to collar connections to duct-board and/or sheet metal; seal around the connection with mastic;

• Connections between collars and distribution boxes should be sealed with mastic or approved tape;

• At least three equally-spaced #8 screws should be used to mechanically fasten round ducts (3 screws for ducts up to 12" diameter, and 5 screws for ducts over 12" diameter);

• Crimp joints should have a contact lap of at least 1-1/2 inches;

• Square or rectangular ducts should be mechanically fastened with at least one screw per side.

Duct Board

• Duct board connections should be sealed with adhesive, mastic, or UL 181A listed pressure-sensitive or heat-activated tape in accordance with manufacturer's specifications.

Duct Support

• Supports should be installed per manufacturer's specifications or per UMC requirements;

• Supports for flexible ducts should be spaced at no more than 4 foot intervals;

• Flexible ducts should be supported by strapping having a minimum width of 1-1/2 inches at all contact points with the duct;

• Supports should not constrict the inner liner of the duct;

• Flexible ducts should have maximum of 1/2 inch sag per foot between supports;

• Flexible ducts may rest on ceiling joists or truss supports as long as they lie flat and are supported at no more that 4 foot intervals.

Boots

• After mechanically attaching the register boot to floor, wall, or ceiling, all openings between the boot and floor, wall, or ceiling should be sealed with caulk or mastic.

Manufacturers Web Sites:

JPL : http://www.jplflex.com/docs/ulinst_f.pdf

ANCO : http://www.ancoproductsinc.com/flex_duct/spec_sheets/flex_4625.pdf

Thermaflex: http://www.thermaflex.net/hvac.php?aud=hva

Others: http://www.directindustry.com/industrial-manufacturer/ventilation-duct-79826.html

ATCO  Manufacturer’s Installation Guide:
 http://www.atcoflex.com