Hearth & Home Technologies 21M-ACC User Manual

Page  6

7039-131F

September 1, 2008

R

Marginal Location:

•  Below peak

Location NOT recommended:

•  Not the highest point of the roof

•  Wind loading possible

Multi-level Roofs

Windward 

Leeward

Recommended:

Outside Air Intake

on windward side

NOT recommended:

Outside Air Intake

on leeward side

Recommended Location:

•  Above peak

Recommended:

•  Insulated exterior chase 

in cooler climates

Recommended Location:

•  Above peak

•  Inside heated space

Location NOT recommended:

•  Too close to tree

•  Below adjacent structure

•  Lower roof line

•  Avoid outside wall

Marginal Location:

•  Wind loading possible

Draft is the pressure difference needed to vent appliances 

successfully.  Considerations for successful draft include:
  •  Preventing negative pressure
  •  Location of appliance and chimney

Negative pressure results from the imbalance of air avail-

able for the stove to operate properly.  Causes for this imbal-

ance include:
  •  Exhaust fans (kitchen, bath) etc.)
  •  Range hoods
  •  Combustion  air  requirements  for  furnaces,  water 

heaters and other combustion appliances

  •  Clothes dryers
  •  Location  of  return-air  vents  to  furnace  or  air  condi-

tioning

  •  Imbalances of HVAC air handling system
  •  Upper level air leaks
   

•  Recessed lighting

   

•  Attic hatch opening

   

•  Duct leaks

To minimize the affects of negative air pressure the following 

must be considered:
  •  Install  the  outside  air  kit.    Install  the  intake  on  the 

side of the house towards prevailing winds during the 

heating season.

  •  Ensure adequate outdoor air is supplied for combus-

tion appliances and exhaust equipment.

  •  Ensure furnace and air conditioning return vents are 

not  located  in  the  immediate  vicinity  of  the  appli-

ance,

  •  Avoid installing the appliance near doors, walkways 

or small isolated spaces.

  •  Recessed lighting should be of “sealed can” design; 

attic  hatches  weather  stripped  or  sealed;  and  attic 

mounted ductwork and air handler joints and seams 

taped or sealed.

•  Negative pressure can cause spillage of com-

bustion fumes, soot and carbon monoxide.

•  Appliance needs to draft properly for safety.