Heat pumps are the workhorses of modern home climate control. Unlike traditional furnaces that generate heat by burning fuel, or air conditioners that only cool, a heat pump is a highly efficient “energy mover.” In a place like Guelph, where we run the gamut from humid 30°C summers to bone-chilling -20°C winters, your heat pump is likely the most active mechanical system in your home.
Because it operates year-round, maintenance isn’t just a “good idea”—it is a financial necessity. A well-maintained unit can lower energy bills by up to 25% and extend the lifespan of the equipment by a decade.
This comprehensive guide covers everything from simple DIY habits to the technical nuances that require a professional touch.
Maintenance doesn’t always require a toolbox. Many of the most impactful actions are about observation and basic cleanliness.
The single most common cause of heat pump failure is restricted airflow.
Check monthly: If you have pets or live in a dusty area, check your filters every 30 days.
The “Light Test”: Hold your filter up to a light bulb. If you can’t see the light through it, the air can’t get through it either.
Don’t “Over-Filter”: Avoid high-MERV filters (13+) unless your system is specifically designed for them. They can be so thick that they actually strain the blower motor, leading to an expensive repair.
Your outdoor unit (the condenser) needs to breathe.
Clear the Perimeter: Keep a 2-foot (60 cm) clearance around the unit. Trim back shrubs, weeds, and long grass.
Check the Fins: The aluminum fins on the side of the unit are delicate. If they are flattened by a rogue hailstone or a lawnmower stone, they block airflow. You can buy a “fin comb” to straighten them, but be extremely gentle.
Gently Rinse: Once a season, use a garden hose (never a pressure washer!) to rinse away dust, pollen, and cottonwood seeds from the outdoor coils.
While homeowners can handle the “lungs” (filters) and the “skin” (unit exterior), the “heart” and “nerves” of the system belong to a licensed technician.
Even if the system seems fine, a professional should visit once a year (ideally in the spring or fall). They will check:
Refrigerant Levels: Too much or too little refrigerant forces the compressor to work harder, eventually leading to burnout.
Electrical Connections: Heat pumps vibrate. Over time, wires can loosen or corrode, leading to electrical shorts or fire hazards.
Condensate Drain Lines: Technicians clear the sludge that builds up in the drain lines, preventing water damage to your floors or basement.
Short-Cycling: If the unit turns on and off every few minutes, it’s likely overheating or has a faulty sensor.
Ice Buildup in Summer: Seeing ice on your indoor or outdoor coils during a heatwave is a sign of a refrigerant leak or a major airflow blockage.
The “Burning” Smell: A faint dusty smell when the heat first kicks on is normal, but an electrical “acrid” smell means a component is melting.
Understanding common failures helps you catch them before they become $3,000 replacements.
The reversing valve is what allows the heat pump to switch between heating and cooling. If your unit is blowing cold air in the winter and won’t switch back, the solenoid on this valve has likely failed.
In the winter, your outdoor unit will frost over. This is normal. The unit should periodically enter “Defrost Mode” to melt that ice. If the defrost board is faulty, the unit will become a solid block of ice, eventually crushing the internal coils.
Think of the capacitor as a giant battery that gives the motor a “kickstart.” These are highly sensitive to heat and power surges. If you hear a “humming” sound but the fan isn’t spinning, it’s usually a dead capacitor—a relatively cheap and quick fix for a pro.
In Ontario, our weather dictates our maintenance schedule.
Elevation: Ensure your unit is on a stand (usually 6–12 inches high). If snow drifts bury the unit, it cannot pull heat from the air.
Ice Falling from Roofs: If your unit is under an eave, ensure there is a “snow shield” or “hat” over it. A large chunk of ice falling from a roof can smash the fan blades and motor instantly.
Spring is the time for the “Great Rinse.” Cottonwood seeds and dandelion fluff are the enemies of efficiency. They act like a blanket over your coils, trapping heat inside.
When cooling, your heat pump acts as a dehumidifier. Ensure the “P-trap” or condensate pump is working. If you see water pooling around the indoor air handler, your drain is clogged.
The way you interact with your thermostat can save (or cost) you hundreds of dollars.
Unlike a gas furnace, which can ramp up heat very quickly, heat pumps are “slow and steady” machines.
The Mistake: Turning the heat down to 16°C while at work and then cranking it to 21°C when you get home.
The Result: The heat pump realizes it can’t bridge that 5-degree gap quickly enough, so it engages the “Emergency Heat” or “Auxiliary Heat” (electric heat strips). Electric strips are 3–4 times more expensive to run than the heat pump itself.
The Strategy: Do not adjust your thermostat by more than 2 degrees at a time.
Ensure your thermostat is not mounted near a drafty window or a heat-producing appliance (like a lamp or oven). This causes “false readings,” leading to uneven cycling.
Are you accidentally sabotaging your system?
Closing Vents: You might think closing vents in unused rooms saves money. It doesn’t. It increases static pressure in your ductwork, which can blow out your blower motor or cause the coils to freeze. Keep at least 80% of your vents open at all times.
Neglecting the “Weep Holes”: The base of your outdoor unit has small holes to let melt-water escape. If these get plugged with dirt or leaves, the water freezes into a solid sheet of ice at the bottom, which can damage the fan.
Crowding the Indoor Unit: Don’t stack boxes or build shelves right up against your furnace or air handler. The system needs “return air” to circulate through the house.
Given our local climate and utility rates, there are a few extra things to consider.
Many local homeowners use a “Hybrid” setup—an electric heat pump paired with a high-efficiency gas furnace.
The Switchover Point: A technician can set your system to use the heat pump when it’s above -5°C (when it’s most efficient) and automatically switch to gas when it gets colder. This balances your hydro and gas bills perfectly.
Every 3–5 years, ask for a “Chemical Coil Cleaning.” Over time, a film of biofilm and oxidation builds up on the coils that a garden hose can’t touch. A specialized foaming cleanser can restore the unit to nearly “factory-new” efficiency.
| Frequency | Task |
| Monthly | Check/Change Filters, Check Outdoor Unit for Debris. |
| Seasonally | Clear snow/ice, rinse coils with a hose, ensure vents are open. |
| Annually | Professional multi-point inspection and electrical check. |
| As Needed | Straighten bent fins, clear condensate drain lines. |
The Bottom Line: Your heat pump is an investment in your home’s comfort and value. By spending 15 minutes a month on DIY care and scheduling one professional visit a year, you prevent the vast majority of “no-heat” emergencies.
Would you like me to create a specific maintenance schedule template you can print out for your clients, or perhaps a guide on how to explain the “Auxiliary Heat” costs to them?
