Fedders F80A dimensions Guide, Ductwork Steps

DUCTWORK

Proper airflow is required for the correct operation of this furnace. Insufficient airflow may cause erratic operation, could cause the furnace to cycle on the high temperature limit, and may damage the heat exchanger. Excessive airflow may result in an excessively noisy duct system and may result in undesirable consequences such as creating uncomfortable drafts and causing drapes or curtains to blow around.

If air conditioning is to be used with the furnace, the duct system must be capable of delivering the correct amount of airflow for each system.

The ductwork should be sized and constructed in accordance with accepted industry standards. Duct sizing and construction information may be obtained from:

•A.C.C.A. (Air Conditioning Contractors of America)

•A.S.H.R.A.E. (American Society of Heating, Refrigeration and Air Conditioning Engineers)

•H.R.A.I. (Heating, Refrigerating and Air Conditioning Institute (Canada)

•S.M.A.C.N.A. (Sheet Metal and Air Conditioning Contractors’ National Association (United States)

All of the above professional organizations have duct sizing manuals available.

The total static pressure drop of the air distribution system should not exceed 0.5 inches water column.

NOTE:

UNITS 70-4, 100-5, 115-5 AND 135-5 MUST HAVE DUAL RETURN AIR INLETS FOR OPTIMAL AIRFLOW AND AIR FILTRATION. IF NOT SPECIFICALLY STATED BY THE FILTER MANUFACTURER, FOR EFFECTIVE AIR FILTRATION, ASSUME A MAXIMUM VELOCITY OF 300 FPM FOR DISPOSABLE TYPE FILTERS, OR 600 FPM FOR PERMANENT TYPE FILTERS.

GUIDE:

Filter free area (in2) = 144 x (CFM / desired velocity (fpm))

IMPORTANT: Some high efficiency filters have a greater than normal resistance to airflow. This can adversely affect furnace operation. Ensure to check the airflow when using any filter.

WARNING

DO NOT, UNDER ANY CIRCUMSTANCES, CONNECT RETURN OR SUPPLY AIR DUCTWORK TO OR FROM ANY OTHER HEAT-PRODUCING DEVICE SUCH AS A FIREPLACE INSERT, STOVE, ETC. DOING SO MAY RESULT IN FIRE, CARBON MONOXIDE POISONING, EXPLOSION, PERSONAL INJURY, LOSS OF LIFE, OR PROPERTY DAMAGE.

6

WARM AIR FURNACE

DUCTWORK STEPS:

1.Position the furnace to minimize ductwork length and fittings.

2.Cut open a return air inlet. The choices are:

a)either side

b)furnace bottom

c)any combination, i.e. two sides or a side and the bottom. Note: 2 return openings required for 70-4, 100-5, 115-5 and 135-5.

CAUTION

DO NOT USE THE REAR PANEL AS A RETURN AIR INLET. THERE IS INSUFFICIENT ROOM TO PERMIT ADEQUATE AIRFLOW.

In all cases, cut the inlet air opening the full width of the knockouts.

NOTE: When two return air inlets are used, both must be equipped with filters.

3.Install the filter rack(s) (field supplied).

4.Connect the return air duct or fitting to the furnace. The connection should be as air tight as possible to prevent entraining combustion gases from an adjacent fuel burning appliance, or entraining combustion air for this furnace .

5.Ensure that there is adequate space and accessibility for the air filter.

6.If an air conditioning evaporator coil is required, position it on the top of the furnace. Ensure that no air can bypass the evaporator coil.

7.Connect the supply air plenum to the supply air outlet. Flexible duct connectors are an effective device to prevent the telegraphing of mechanical noise from the furnace to other parts of the home via the ductwork. If using flexible connectors, ensure that the adjoining duct is independently supported.

Adequate provisions for combustion and ventilation air must be in accordance with ANSI Z223.1 (NFPA 54), section

5.3"Air for Combustion and Ventilation" in the United States, and CAN/CGA B149 in Canada. Check with local authorities for any additional building codes, bylaws or regulations.

WARNING

NEVER ALLOW THE PRODUCTS OF COMBUSTION FROM THE FLUE TO ENTER THE RETURN AIR OR SUPPLY AIR DUCTWORK.

ALL RETURN AIR DUCTWORK MUST BE ADEQUATELY SEALED AND SECURED TO THE FURNACE WITH SHEET METAL SCREWS. TAPE THE SHEET METAL SEAMS IN THE VICINITY OF THE FURNACE WITH DUCT TAPE OR SIMILAR MATERIAL.

WHEN THE FURNACE IS MOUNTED ON A PLATFORM WITH RETURN AIR THROUGH THE BOTTOM, IT MUST BE SEALED AIR TIGHT BETWEEN THE FURNACE AND THE RETURN AIR PLENUM. THE FLOOR OR PLATFORM MUST PROVIDE SOUND PHYSICAL SUPPORT OF THE FURNACE WITHOUT SAGGING, CRACKS OR GAPS AROUND THE BASE, PROVIDING A SEAL BETWEEN THE SUPPORT AND THE BASE.

FAILURE TO PREVENT PRODUCTS OF COMBUSTION FROM BEING CIRCULATED INTO THE LIVING SPACE CAN CREATE POTENTIALLY HAZARDOUS CONDITIONS, INCLUDING CARBON MONOXIDE POISONING THAT COULD RESULT IN PERSONAL INJURY OR DEATH.