If you've ever switched on your heat pump only to be greeted by a musty, "wet dog" smell, you're not alone. In our damp South Island climate, from the coastal breeze in Mapua to the cooler mornings in Wakefield, heat pumps work hard, and sometimes they start to smell.
A funky odour isn't just annoying; it's a sign your unit needs a bit of TLC. Whether you're in Richmond, Brightwater, Motueka or anywhere in between, here are five pro tips to keep your air fresh and your home healthy.
1. Clean Your Filters Every 3 Months
This is the #1 rule for any Nelson-Tasman homeowner. When filters are clogged with dust, that debris bypasses the screen and sticks to the damp internal coils, creating a breeding ground for mould and bacteria.
✅ The Fix: You can't have a "too clean" filter. Wash them in lukewarm water and dry them before putting them back in.
2. The "Dry-Out" Hack (Fan Only Mode)
When you use your heat pump for cooling, the internal coil becomes saturated with water. If you turn it off immediately, that moisture stays trapped in a warm unit: the perfect nursery for mould.
✅ The Fix: Before you leave the house or go to bed, switch to "Fan Only" mode for 5–10 minutes. This dries the coil out completely and stops smells before they start.
3. Check Your External Drain Line
Did you know your heat pump can draw a small amount of air back through the drain pipe? If your drain terminates near a compost bin, a damp garden bed, or a sewer vent, those smells will end up in your lounge.
✅ The Fix: Take a quick walk outside. Ensure your drain line is clear and isn't sitting in stagnant water or near smelly areas.
4. Turn the Unit Off While Cooking
Whether you're frying up dinner or using strong spices, fats and aromas get sucked into the heat pump's intake. They stick to the wet coils and "reactivate" the smell every time the system runs.
✅ The Habit: Switch the heat pump off while cooking to keep your indoor air quality high and your coils grease-free.
5. Avoid Harsh Chemicals and Detergents
It's tempting to spray household cleaners inside to "freshen" things up. However, many detergents leave a residue that you'll smell every time the unit turns on.
⚠️ The Warning: If you clean your heat pump with a standard detergent, you will smell chemical fumes for weeks. Always use specialised heat pump cleaners, or stick to plain water for DIY maintenance.
Does Your Heat Pump Need a Deep Clean?
If you've tried these tips and your heat pump still has a funky odour, or if you notice uneven airflow, it's likely time for a professional strip-clean. Unlike a DIY tidy-up, a professional deep clean dismantles the unit to clean the fan wheel and internal components. I provide professional heat pump deep cleaning for homes across Nelson, Richmond, and the wider Tasman District.
Ready for fresh air? Book online today.