Looking After a Heat Pump in the Snow
What’s normal, what needs attention, and how to avoid the most common winter problems.
Can Heat Pumps Work in Snow?
Yes. Modern heat pumps are designed to operate in cold, snowy conditions. Seeing frost, steam, and regular defrost cycles is often normal winter behaviour.
The main risks during snowfall aren’t “the cold” itself — they’re usually blocked airflow, frozen drain paths, and meltwater refreezing in the wrong place.
1) Keep the Outdoor Unit Clear
Your outdoor unit needs steady airflow. Snow drifting against the sides or rear can reduce performance and increase icing.
What to check
- Snow piled around the unit
- Snow packed against the rear or sides
- Drifts forming underneath the unit
- Leaves or debris trapped in the intake/exhaust area
What to do
- Gently clear snow with a soft brush or gloved hand
- Try to keep 300–500 mm of clear space around the air paths
- Re-check after overnight snowfall or windy conditions
- Don’t chip ice off the coil with tools
- Don’t pour hot water over the unit
- Don’t spray de-icing chemicals onto the coil or fan area
2) Understand the Defrost Cycle
In cold, damp weather the outdoor coil can frost up. The heat pump removes this by running a defrost cycle. Defrost is normal — and in snowy weather it may happen frequently.
Normal signs of defrost
- Steam or vapour rising from the outdoor unit
- The outdoor fan stopping briefly
- Clicking sounds as valves switch
- A short dip in heating output
If the unit completes defrost and then returns to normal heating, that’s usually a healthy sign.
3) Check the Condensate Drain (Very Important)
One of the most common winter issues is condensate freezing. During defrost, ice melts off the coil and must drain away. If it refreezes under the unit, you can get a growing “ice plinth”.
What to look for
- An ice mound building up beneath the unit
- No visible draining during/after defrost (when conditions suggest it should be draining)
- Fans struggling or noisy operation because ice is encroaching
- Faults that only occur in freezing weather
Preventive steps (safe homeowner checks)
- Make sure any drain route slopes downward and isn’t buried in snow
- Keep the discharge point clear so meltwater can escape
- If freezing is common where you live, ask your installer about insulation or trace heating for the drain
4) Don’t Turn the Heat Pump Off “Until the Snow Passes”
It’s tempting to switch the system off in bad weather, but that can make things worse. Heat pumps manage frost and defrost best when they’re left to run steadily.
Why leaving it running is usually better
- The system can self-manage frost build-up and defrost timing
- Circulation helps reduce freeze risk (depending on system design)
- Restarting from cold can increase electricity use and strain
If your home feels cooler, try small changes rather than switching off: increase the setpoint slightly and give it time to stabilise.
5) Watch for Warning Signs
Call an engineer if you see persistent or worsening symptoms — especially if the unit can’t clear ice properly.
Call for help if you notice
- The outdoor unit encased in solid ice
- Loud grinding noises (fan obstruction) or repeated stoppages
- Repeated fault codes that return after basic checks
- No heating output despite long run times
- Confirm the system has power and hasn’t tripped at the consumer unit
- Clear snow from air paths (gently)
- Look for an ice mound under the unit and blocked drainage
Winter Maintenance Checklist
- Clear snow from around the outdoor unit (especially rear/sides)
- Expect steam/noise during defrost — it’s usually normal
- Check the condensate drain isn’t freezing into an ice mound
- Leave the system running steadily where possible
- Call an engineer if ice becomes solid, persistent, or performance collapses
Key Takeaway
Snow rarely damages a heat pump directly. The real issues are usually blocked airflow and frozen drainage. A few simple checks after snowfall can prevent most winter breakdowns.