Tjernlund RVB3 Roof Vent Booster Fan 8504173 (Discontinued) - Manual (Page 2)

DESCRIPTION
A Powered Roof Vent Booster (RVB) is a simple and safe way to increase attic ventilation. RVB’s allow you to avoid the
hassle and danger of working on top of the roof. They install from inside the attic against the underside of standard roof
vents with openings up to 11” square. They boost ventilation by over 3 times that of passive roof vents, helping to keep
the attic space the same temperature as the outside. NOTE: Use of the RVB will aid in the prevention of ice dams, but
does not reduce existing ice dams.
Adjustable arms secure the booster in place between roof rafters/trusses up to 32” across. No wiring is necessary, just
plug the Powered Roof Vent Booster into an outlet. Operates on only 60 Watts. When using more than 1 RVB, plug one
fan into another for multiple unit operation through a single power source (8 unit maximum). Position Powered Roof Vent
Booster(s) over roof vents near and above areas with severe ice damming.
SPECIFICATIONS
RECOMMENDED METHODS AND PATTERNS OF OPERATION
How to determine the number of Powered Roof Vent Boosters needed:
Calculate the cubic area of the attic by multiplying the Length x Width x (1/2) Height (assumes a pitched roof). Divide
this number by 10 to determine the minimum CFM necessary to fully ventilate the space in 10 minutes.
Example: 20' wide x 40' long x (1/2) 6' high attic = 2400 cubic ft.
2400 cubic ft. ÷ 10 minutes = 240 CFM of ventilation. Choose one RVB3.
Choose one RVB3 for every 300 CFM, rounding up.
Increasing Ventilation to Eliminate Ice Dams
Ice Dams are a common problem in regions that regularly have snow. They are caused by upper portions of a roof sur-
face warming to over 32 degrees, which melts the snow. The resulting water refreezes near the roof’s edge where sur-
face temperatures are lower, forming a dam of ice. When the water can no longer flow down over the dam it backs up
the roof and underneath shingles causing interior water damage and shingle damage.
Generally Recommended Procedures for Eliminating Ice Dams:
• Find and seal air leaks from the heated living space into attic around openings for bath fans, heating or dryer exhaust ducts.
• Add insulation to the floor of the attic. Remove insulation from soffit openings in attic space.
• Ventilate the space using the RVB so that the underside of the upper roof surface stays below 32 degrees. This may
be easiest by locating RVB units over roof vents near and above areas that have had ice dams in the past. Make sure
that soffit vents and roof vents are clear of debris or other obstructions.
Increasing Ventilation to Exhaust Summertime Heat from Attics
Roof Vent Boosters can be used in place of traditional attic fans to increase attic ventilation and decrease cooling costs
during the hot summer months. Exhausting pent-up attic heat will decrease the amount of energy needed to cool your
home. If a large amount of ventilation is required, the RVB units can be daisy-chained with one unit plugged into the
next so that only one power source is needed for all fans (8 unit maximum).
INSTALLATION
1. Apply included foam tape to exterior edge of RVB. This will decrease leakage of air flow from the fans and minimize any unit
vibration, (See Diagram A).
2. Center RVB over opening of existing roof vent opening, (See Diag. B). Locate electrical outlet side on roof peak side, (See Diag. C).
1
Dimensions/Performance Electrical
Length 12” Voltage 115 VAC
Width 12” RPM 3000
Depth 3.5” Watts 60
CFM 300 Amps 0.9 (max.)
Diagram A
Diagram B, Typical Roof Vent
Opening View from Inside Attic
Diagram C