10
Installing duct to/from inside
To maximize airflow in the ductwork system, all ducts should be kept short and have as few bends or elbows as
possible. Forty-five degree are preferred to 90º elbows. Use “Y” tees instead of 90º elbows whenever possible.
All duct joints must be fastened with screws or duct sealant and wrapped with a quality tape to prevent leakage.
Aluminum foil duct tape is recommended. Galvanized ducting from the HRV/ERV to the living areas in the house is
recommended whenever possible, although flexible duct can be used in moderation when necessary.
The SH704 & VH704 should be installed with a 4” (100mm) duct system that has less than 80 ft
(25m) of equivalent duct length on the supply and on the exhaust side. If longer runs are required,
increasing the duct diameter or following the instructions below might help.
It is the responsibility of the installer to ensure all ductwork is sized and installed as designed to
ensure the system will perform as intended. All air movement devices have a performance curve.
The amount of air (CFM) that an HRV/ERV will deliver is directly related to the total external static
pressure (E.S.P.) of the system. Static pressure is a measure of resistance imposed on the blower by length of duct
work/number of fittings used in duct work, duct heater etc..
Supply air ducting
In homes without a forced air furnace, fresh air should be supplied to all habitable rooms including, bedrooms and
living areas. It should be supplied from high wall or ceiling locations. Grilles that diffuse the air comfortably such as
Fantech Contour Grilles are recommended. To avoid possible noise transfer through the ductwork system, a short
length (approximately 12”, 300 mm) of nonmetallic flexible insulated duct should be connected between the HRV/
ERV and the supply/exhaust ductwork system.
If the floor is the only option available, then special care should be taken in locating grilles. Areas such as under
baseboard heaters will help to temper the air. Also optional inline duct heaters are available for mounting in the
supply duct work to add heat if required. In homes with a forced air furnace, you may want to connect the HRV/ERV
to the furnace ductwork (see information below).
Exhaust air ducting
The stale air exhaust system is used to draw air from the points in the house where the worst air quality problems occur. Due to its lower capacity,
the SH704, VH704 and SE704 are designed to vent from a single source point only and to the bathroom that is closest to the unit or directly out of
the furnace return. Additional source points may be drained from if designed properly or installed on a separate Fantech fan bath kit to ventilate
additional areas. Fantech bath kits are listed below and are ideal for both new construction and retro fit.
• Building Codes and
Combustion Appliance
Installation Codes do not
allow location of return air
grilles or any opening such
as a “breathing tee” in an
enclosed room with spillage
susceptible combustion
appliances.
• The fresh air inlet from
the HRV needs to respect
a minimum distance
from the furnace return
drop to ensure proper air
mixing and temperature
at the furnace core. See
furnace manufacturer for
appropriate specifications.
