Lifebreath 700FD/DD Benutzerhandbuch

It is recommended that a licensed electrician make all
electrical connections.  It is very important that the 
unit be properly grounded.  It is recommended that a
separate 15 amp/120 volt circuit be used. 

In order to prevent electric shock when 

cleaning or servicing the HRV/ERV, it is extremely 
important to confirm the polarity of the power line that is
switched by the safety (disconnect) switch whose control
arm is located on the outside of the electrical control box
area. The hot line (black) is the proper line to be switched.
To confirm the proper polarity, use a voltmeter or test lamp
to make sure there is no power after the switch when the
door is open. Check between that point and ground (on the
cabinet). This must be done as occasionally some 
buildings are improperly wired.  Always make sure the
HRV/ERV is properly grounded.

Fan defrost HRV’s are equipped with an electronically
controlled fan defrost system to remove frost that 
collects on the warm air side of the aluminum heat
transfer surfaces of the heat exchanger core.  When
the outside air temperature drops below 27˚F(-3˚C),
defrost  is activated which provides for an automatic
defrost cycle.  During the automatic defrost cycle the
fresh air supply  is shut off while the exhaust fan contin
ues to operate.  This allows warm inside air to 
flow through the heat exchanger core melting frost 

accumulation.  After the defrost period, the fresh air
supply fan automatically returns to the normal speed
and fresh outside air continues to be drawn into the
building.  Water from the melted frost collects in the
bottom drip pans and drains out through the bottom
drain connections. The defrost cycle repeats 
automatically until the air temperature rises 
above 27˚F(-3˚C).

These damper defrost HRV’s have an electronically
controlled damper defrost  mechanism. If the outside
temperature drops below 27˚F(-3˚C ), the defrost timer
is activated. A motor driven damper door mechanism
opens the defrost port and at the same time closes off
the supply air from outside. After approximately 3 
minutes, the damper operates in the opposite direction 
to close off the defrost port and reopen the fresh air at
the supply port.  The 27.5 minute wait time and 3
minute defrost cycle repeat until the temperature again
rises above  27˚F (-3˚C).

If confirmation of the defrost system is needed, 
complete the following steps.

1. Disconnect power to the unit and open access/

maintenance doors.

2. Locate the “snap disc” type temperature sensor 

mounted in the upper left hand corner (cold air 
stream) of the HRV.

3. Disconnect the two wires from the HRV to the 

sensor, at the sensor.

4. Using a jump wire with alligator clips, join two 

wires from the HRV together.

5. Close access doors and power the unit.

This procedure will simulate a defrost that would occur
automatically in the field when the outside temperature
drops below -3˚C (27˚F).