17
Poor Air Flow
Supply air feels cold
Dehumidistat is not Operating
Humidity Levels are too High in Winter
Condensation is appearing on the
windows
Humidity Levels are too Low
HRV and / or Ducts Frosting up
Condensation or Ice Build Up in
Insulated Duct to the Outside
Water in the bottom of the HRV
• 1/4” (6mm) mesh on the outside hoods is plugged
• filters plugged
• core obstructed
• house grilles closed or blocked
• dampers are closed if installed
• poor power supply at site
• duct is restricting HRV
• improper speed control setting
• HRV air flow improperly balanced
• poor location of supply grilles, the air flow may irritate
the occupant
• outdoor temperature extremely cold
• improper connection to ventilator
• external low voltage is shortened out by a staple or nail
• check dehumidistat setting it may be on OFF
• dehumidistat is set too high
.• lifestyle of the occupants
• moisture coming into the home from an unvented or
unheated crawl space
• moisture is remaining in the washroom/bathroom and
kitchen areas
• condensation seems to form in the spring and fall
• HRV is set at too low a speed
• dehumidistat control set too low
• blower speed of HRV is too high
• lifestyle of occupants
• HRV air flow may be improperly balanced
• HRV air flow is improperly balanced
• malfunction of the HRV defrost system
• incomplete vapor barrier around insulated duct
• a hole or tear in outer duct covering
• drain pans plugged
• improper connection of HRV drain lines
• HRV is not level
• drain lines are obstructed
• HRV heat exchange core is not properly installed
• clean exterior hoods or vents
• remove and clean filter
• remove and clean core
• check and open grilles
• open and adjust dampers
• have electrician check supply voltage at house
• check duct installation
• increase the speed of the HRV
• have contractor balance HRV
• locate the grilles high on the walls or under the baseboards,
install ceiling mounted diffuser or grilles so as not to directly
spill the supply air on the occupant (eg. over a sofa)
• turn down the HRV supply speed. A small duct heater
(1kw) could be used to temper the supply air
• placement of furniture or closed doors is restricting themove-
ment of air in the home
• if supply air is ducted into air handler return, the air handler
fan may need to run continuously to distribute ventilation air
comfortably
• check that the correct terminals have been used
• check external wiring for a short
• set the dehumidistat at the desired setting
• set dehumidistat lower
• avoid hanging clothes to dry, storing wood and venting
clothes dryer inside. Heating wood may have to be moved
outside
• vent crawl space and place a vapor barrier on the floor of the
crawl space
• ducts from the washroom/bathroom should be sized to
remove moist air as effectively as possible, use of a wash-
room/bathroom fan for short periods will remove additional
moisture
• timer or fan can be added to washroom/bathroom exhaust
• on humid days, as the seasons change, some condensation
may appear but the home’s air quality will remain high with
some HRV use
• increase speed of the HRV
• set dehumidistat higher
• decrease HRV blower speed
• humidity may have to be added through the use of humidi-
fiers
• have a contractor balance HRV air flow
• Note: minimal frost build-up is expected on cores before
unit initiates defrost cycle functions
• have HVAC contractor balance the HRV
• ensure working properly.
• tape and seal all joints
• tape any holes or tears made in the outer duct covering
• ensure that the vapor barrier is completely sealed
• ensure O-Ring on drain nozzle sits properly
• look for kinks in line
• check water drain connections
• make sure water drains properly from pan
Troubleshooting
Symptom
Cause
Solution
