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