Fantech VHR 704 Manuel D'installation page 8

8
Installation examples (Cont'd)
DIRECT CONNECTION of the HRV SUPPLY AIR STREAM to the SUPPLY AIR SIDE on the
FURNACE & ExHAUST AIR STREAM to the FURNACE COLD AIR RETURN
SIMPLIFIED INSTALLATION (GOOD)
OPTION 2
1. Furnace blower must operate when ventilation from HRV is required. The
furnace should be set to run continuously or interlocked with HRV.
2. Due to the differences in pressure between the HRV and the equipment it is
being connected to, the HRV's airflow must be balanced on site, using the
procedure found section "AIRFLOW BALANCING".
HRV/Furnace ducting for Simplified Installation - Option 2
* Ductwork layout may differ depend-
ing on model
Fresh air from
outside
Outside
Stale air to
outside
Fantech heat recovery ventilators (HRV) that use a supply fan shutdown for frost preven-
tion do not include an outdoor air motorized damper. If you are using a simplified installa-
tion, i.e. connecting the HRV supply air duct to a furnace's return air duct, the HRV must
operate continuously. when the HRV is turned off, no warm exhaust air will flow through
the HRV but the furnace's fan will continue to draw in outdoor air directly into the furnace.
If it's cold outside, cold air will be introduced, without re-heating, directly into the furnace.
If the HRV is installed such that the homeowner may turn off the HRV during the winter, we
recommend installing a motorized damper between the HRV's supply air and the furnace's
return air duct that closes when the HRV is not operating. See wiring diagram (figure 1).
you may also choose to use a Fantech HRV that uses a recirculation defrost that incorpo-
rates an outdoor air damper.
fantech
Air from inside
* Unit air flow should be balanced while HRV is on "Normal" speed and
furnace blower is running.
1 m (3' 3") min.
recommended
Motorized
Damper
Fresh air to living areas
Cold air
return
Suggested installation for:
• When bathroom and
kitchen already have local
exhaust system
• May be suitable for
retrofitting
Benefits: Least expensive
installation type
In the case of a simplified
installation, Option 1 is
recommended.
24 VAC Transformer
24V
120V
NO
COM
HRV Furnace interlock
See page 15.
Figure 1
*Transformer and Damper motor not included
Motorized
Damper
Damper
Motor