Nortek B6BV Series, Installation Instructions Manual

5

Requirements for sealing ducts vary from region to 

region. Consult with local codes for requirements specific 

to your area.

Return Air connections

For each application in the USA, the home manufacturer 

shall comply with all of the following conditions to have 

acceptable return air systems for closet installed forced 

air heating appliances:

•  regardless of the location, the return air opening into the 

closet shall not be less than specified in the appliance’s 

listing.

•  means shall be provided to prevent inadvertent closure 

by a flat object placed over the return air opening when 

it is located in the floor of the closet (versus the vertical 

front or side wall).

•  The  cross-sectional  area  of  the  return  duct  system 

leading into the closet shall not be less than 390 in

2

.

•  The total free area of openings in the floor or ceiling 

registers serving the return air duct system must be at 

least 352 in

2

. At least one register should be located 

where it is not likely to be covered by carpeting, boxes 

and other objects.

•  materials located in the return duct system must have a 

flame spread classification of 200 or less. This includes 

a closet door if the air handler is in a closet.

•  Test the negative pressure in the closet with the air-

circulating fan operating at high speed and the closet 

closed. The negative pressure is to be no more negative 

than minus 0.05 inch water column.

•  For  floor  return  systems,  the  manufactured  home 

manufacturer shall affix a prominent marking on or 

near the appliance where it can be easily read when 

the closet door is open. The marking shall read:

 cAUtIoN:

ASpHYXIAtIoN HAZARD: Do not cover or restrict 

return air opening.

•  The return air opening can be located in a closet door or 

a sidewall. If the return air opening is directly adjacent 

to the side (or front) of the air handler, 6” minimum 

clearance must be provided between the side of the 

air handler and the return air opening. If no part of the 

return air opening is directly adjacent to the unit no 

clearance is required.

•  In  applications  where  the  supply  ducts  carry  heated 

air to areas outside the space where the air handler 

is installed, the return air must be delivered to the air 

handler by duct(s) secured to the casing, running full 

size and without interruption.

Supply Air connections

•  The supply duct system must be designed so that the 

static pressure measured external to the air handler 

does not exceed the listed static pressure shown on 

the rating plate. The supply air must be delivered to the 

heated space by duct(s) secured to the casing, running 

full length and without interruption.

Unconditioned Spaces

All duct work passing through unconditioned space must 

be properly insulated to minimize duct losses and prevent 

condensation. Use insulation with an outer vapor barrier. 

Refer to local codes for insulation material requirements.

Acoustical Duct Work

•  Certain installations may require the use of acoustical 

lining inside the supply duct work. Acoustical insulation 

must be in accordance with the current revision of the 

Sheet Metal and Air Conditioning Contractors National 

Association (SMACNA) application standard for duct 

liners. Duct lining must be UL classified batts or blankets 

with a fire hazard classification of FHC-25/50 or less.

•  Fiber duct work may be used in place of internal duct 

liners if the fiber duct work is in accordance with the 

current revision of the SMACNA construction standard 

on fibrous glass ducts. Fibrous duct work and internal 

acoustical lining must be NFPA Class 1 air ducts when 

tested per UL Standard 181 for Class 1 ducts.

•  Damping ducts, flexible vibration isolators, or pleated 

media-style filters on the return air inlet of the air 

handler may be used to reduce the transmission of 

equipment noise eminating from the air handler. These 

treatments can produce a quieter installation, particularly 

in the heated space. However, they can increase the 

pressure drop in the duct system. Care must be taken 

to maintain the proper maximum pressure rise across 

the air handler, temperature rise and flow rate. This 

may mean increasing the duct size and/or reducing the 

blower speed. These treatments must be constructed 

and installed in accordance with NFPA and SMACNA 

construction standards. Consult with local codes for 

special requirements. For best sound performance, be 

sure to install all the needed gaskets and grommets 

around penetrations into the air handler, such as for 
electrical wiring.

Air Filters

B6BV series air handlers are not supplied with an air filter 

when shipped from the factory. The installer must provide 

a high velocity filter that is appropriately sized to the return 

air duct opening or filter rack located in the bottom of the 

unit. Accessing the filter does not require tools and can 

be removed from the front of the unit by removing the 
filter door. See Unit Maintenance (

page  11

) for filter 

sizes and installation information.

 WARNING:

Never operate the air handler without a filter 

or with doors removed. Dust and lint can build 

up on internal components, resulting in loss of 

efficiency, equipment damage, and possible fire.