A heat pump outdoor unit (the condenser/compressor unit) needs to sit reasonably level to work efficiently and last its full service life. Fortunately, checking the level is a straightforward DIY task — though any remedial work involving refrigerant or electrical connections must be left to a licensed professional.
Why Level Matters
The compressor inside your outdoor unit relies on oil lubrication that circulates with the refrigerant. If the unit tilts too far, oil can pool away from moving parts, leading to:
- Premature compressor wear and eventual failure
- Excessive vibration and noise, especially at start-up
- Reduced efficiency, meaning higher power bills
- Water not draining properly from the unit's base pan, which can cause corrosion or ice build-up in cold weather
Most manufacturers allow a small tolerance — commonly up to about 3–5 mm across the base frame — but always check your unit's installation manual for the exact specification, as this varies by brand and model.
What You'll Need
- A spirit level (a 600 mm or longer level gives a more accurate reading than a short one)
- A tape measure
- A torch for inspecting underneath the unit
- Optionally, a smartphone with a level app as a quick cross-check
Step-by-Step: How to Check the Level
1. Turn the Unit Off First
Switch the heat pump off at the indoor controller and isolate it at the dedicated isolating switch (usually a weatherproof switch mounted near the outdoor unit). Wait a few minutes before working around the unit.
2. Clear the Area
Remove any debris, leaves or dirt from around the base of the unit so you can see and access the mounting feet or pad clearly.
3. Place the Spirit Level on the Unit Frame
Rest your spirit level directly on the top frame rail of the outdoor unit — not on the fan grille or casing panels, which can flex. Check the level in two directions:
- Front to back (towards and away from the wall)
- Side to side (left to right)
Note where the bubble sits relative to the centre lines.
4. Check the Mounting Surface
Also place the level on the concrete pad, bracket or stand the unit sits on. This tells you whether the pad itself has shifted or whether just the unit's feet need adjustment.
5. Measure Any Gap
If the bubble is noticeably off-centre, use your tape measure to gauge how much one corner is lower than the opposite corner. A difference of more than about 5 mm across the base is worth correcting — but check your installation manual for the manufacturer's stated tolerance.
6. Inspect the Mounting Feet and Anti-Vibration Pads
Look underneath the unit at the rubber anti-vibration mounts or feet. These can compress unevenly over time, especially on older installations. Cracked or collapsed pads are a common cause of units going out of level.
Common Causes of an Unlevel Outdoor Unit
| Cause | What to Look For |
|---|---|
| Concrete pad has settled or cracked | Visible cracks, one corner sunken into soil |
| Anti-vibration pads worn or collapsed | Rubber looks flat, cracked or missing |
| Wall bracket has shifted | Bracket fixing screws loose, wall substrate crumbling |
| Ground movement (expansive soils, tree roots) | Uneven ground around the pad |
What You Can Safely Do Yourself
As a homeowner, you can:
- Check the level as described above
- Clean debris from around the unit and base
- Tighten loose bracket screws if accessible and you are confident doing so safely (with the unit isolated)
- Report your findings to a qualified installer so they can carry out any corrections
Replacing anti-vibration pads or relevelling a wall-mounted bracket is generally within a competent DIYer's ability only if the unit does not need to be moved significantly and no refrigerant lines or electrical connections are disturbed.
When to Call a Professional
Call a licensed heat pump installer if:
- The unit needs to be lifted or repositioned, which risks stressing refrigerant pipework — disturbing refrigerant lines must only be carried out by a suitably qualified and licensed tradesperson — check with your installer or MBIE for the applicable licensing requirements
- The electrical isolator, wiring or connections need to be touched — this is restricted electrical work under the Electrical Workers Registration Board rules
- The concrete pad has cracked or sunk significantly and needs rebuilding
- The wall bracket or fixings look structurally compromised
- You are unsure about anything you find
Installation of heat pump outdoor units must comply with the NZ Building Code (in particular relevant clauses relating to services) and the manufacturer's installation requirements. If your unit was installed under a building consent, any significant repositioning may require council notification — check with your local council if in doubt. The MBIE Building Performance website has useful guidance on what work requires consent.
For peace of mind, a qualified installer can also check refrigerant pressures, electrical connections and overall system performance while they're on site. You can find experienced local heat pump installers on tradedirectory.co.nz.
A Note on Safety
Always isolate the outdoor unit at the dedicated switch before inspecting it closely. Never reach inside the unit casing — internal components can retain charge and fan blades can cause serious injury.
Sources & Further Reading
- MBIE Building Performance – Building Code compliance
- Plumbers, Gasfitters and Drainlayers Board – licensed work
- Electrical Workers Registration Board – restricted electrical work
- BRANZ – guidance on building services and weathertightness
- Energywise – heat pump efficiency tips
- WorkSafe NZ – working safely around electrical equipment
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