Ontario winters can turn heat pumps into ice makers. Homeowners often spot thick icicles on the roof, frozen gutters, and wet, packed snow around the outdoor unit. This is not just cold weather. In many cases, it’s a heat pump causing roof ice dams. Newer systems with a vertical exhaust heat pump design blow warm air upward during defrost cycles. Snow melts at the eaves, refreezes, and ice builds up fast.
Here’s how to tell what’s normal, what’s not, and how to fix it.
Why Heat Pumps Ice Up in Winter?
Some heat pump icing is normal. A light frost on the outdoor coil is expected during cold, damp weather. The unit is pulling heat from cold air. Frost happens. That’s why defrost cycles exist.
But thick ice is a red flag. If you see solid ice sheets on the unit, blocked coils, or ice that does not clear after defrost, you likely have airflow or drain problems. This falls under common heat pump winter issues and heat pump cold weather problems in Ontario.
During a defrost cycle, the system reverses briefly. Warm air blows out. Ice melts. Water drips out of the unit. If that water has nowhere to go, it freezes again. That’s defrost cycle ice buildup in action.
Now aim that warm exhaust straight up at your roofline, and you get heat pump defrost exhaust ice on your eaves.
How Vertical Exhaust Creates Roof Ice Dams?
A roof ice dam heat pump problem often starts with placement. Many outdoor units are installed too close to the house or directly under the eaves. When the system defrosts, warm air rises.
That air melts snow on the roof edge. Water runs a short distance, then freezes again. Over time, this creates heavy ice ridges. That’s how a heat pump, causing roof ice dams, sneaks up on homeowners.
You may also see heat pumps dripping, causing ice below the unit. Frozen puddles form. Snow piles turn into ice blocks. The unit struggles even more. This is one of the most common Ontario heat pump installation issues we see at Don’s Heating and Cooling.
What’s Normal Frost vs Real Trouble?
Here’s the quick test to tell normal winter behavior from a real problem. Light heat pump icing is expected in cold weather. Thin frost on the coils that clears after a defrost cycle is normal. The unit should run steadily, heat the home evenly, and leave the roof above it free of icicles. That’s how a healthy system handles heat pump winter issues.
What’s not normal is thick ice that stays on the unit, a loud fan strain, or weak heat inside the house. If you see icicles forming on the eaves or water freezing under the unit, you’re likely dealing with defrost cycle ice buildup and a heat pump causing roof ice dams. At that point, you don’t need patience. You need a real heat-pump ice-dam fix before the problem gets worse.
Clear Space Around the Unit First!
Start with the basics. Your heat pump needs air. Lots of it.
Clear snow at least 2 to 3 feet around all sides of the unit. Not just the front. All sides. Packed snow blocks airflow and traps moisture. That leads straight to heat pump defrost exhaust ice problems.
Never bury the unit. Never let snowdrifts build up. This simple step alone can reduce heat pump icing a lot.
Why Elevation Matters More Than You Think
In snowy climates like Ontario, many older heat pump units are installed too close to the ground. Here’s what happens when they’re too low:
- Snow piles up around the base during winter storms.
- Meltwater from defrost cycles refreezes at the unit’s bottom.
- Fans and coils get encased in ice, reducing efficiency.
The solution? Raise the unit. A sturdy stand elevates it above typical snow accumulation levels and keeps it clear of pooling water. This simple change:
- Reduces ice buildup during defrost cycles
- Allows proper drainage to function as designed
- Extends the life of your outdoor unit
In Ontario winters, proper elevation isn’t a luxury—it’s essential for your heat pump’s survival.
Don’t Ignore Drainage: It’s the Hidden Cause of Repeated Icing
Even with good elevation, poor drainage can sabotage your heat pump. During defrost cycles, the unit melts ice and produces water that needs somewhere to go. If it can’t drain freely:
- Water refreezes right at the base
- Ice slowly builds up underneath the unit
- Airflow becomes restricted
- Defrost cycles become less effective, leading to more icing
Common culprits include uneven concrete pads, blocked drain paths, or units that have settled over time.
Fixing drainage issues will:
- Prevent those frustrating heat pump icicles
- Stop repeated ice buildup
- Protect your system from long-term damage and expensive repairs
Taking a few minutes to check elevation and drainage now can save you from chasing ice problems all winter long!
Sloped Shields Can Stop Roof Ice Dams!
One smart fix is a simple sloped shield or diverter. This redirects warm exhaust air away from the roofline. It doesn’t trap air. It doesn’t block the fan. It just changes direction.
For many homes, this is the cleanest way to stop roof ice dams from affecting HVAC systems without moving the unit. This works best when combined with correct spacing and height.
Poor Placement Needs a Pro Fix!
Some installs are just wrong. Too close to the wall. Under eaves. In tight corners. These are classic Ontario heat pump installation issues. If your system blasts warm air straight at the roof every defrost, no amount of snow shoveling will solve it.
That’s when you call the installer or a licensed HVAC company. At Don’s Heating and Cooling, we assess placement first. Sometimes the only real heat-pump ice-dam fix is relocation or redesign. This falls under proper heat pump installation, not a patch job.
Maintenance Is Not Optional in Winter!
Regular heat pump maintenance keeps small issues from turning into frozen disasters. Filters, coils, fans, and controls all matter. A dirty coil freezes faster. A weak fan can’t clear the ice. Faulty defrost controls cause long run times and excess meltwater.
If ice keeps coming back, it may be time for heat pump repair. Ignoring it shortens system life and raises energy use.
When to Call Heat Pump Service Pros?
If you see roof icicles forming above your heat pump, don’t wait. Ice dams can damage shingles, gutters, and siding. Water backs up under the roofing. Repairs get expensive fast.
Our heat pump services include inspection, airflow checks, placement review, and winter-ready fixes. We handle new installs, corrections, and full heat pump repair work across Ontario.
Call Don’s Heating and Cooling Today and Get Clear Answers!
We’ll inspect your system, check airflow, drainage, and placement, and explain what’s wrong in plain words. If the issue is poor installation or unit location, we’ll tell you straight and show you the options to fix it. No fluff, no sales talk. Just solid heat pump services and solutions that hold up through real Ontario winters. Contact us today!