Heat Pump Servicing and Repairs: Common Questions

This guide explains what a thorough heat pump service should include, how common faults are investigated and when specialist help is needed. For a one-off annual service, ongoing service plans or fault diagnosis and repairs, use the links below to reach the relevant service page.

When your heat pump stops being “fit and forget”

A new heat pump is often sold as low maintenance and clever.
A few winters later, you’re staring at error codes, noisy cycling, high bills or all three.

This is where proper servicing and fault-finding matter. Not a quick wipe and checkbox, but manufacturer-level diagnostics and optimisation.

In a nutshell, what good servicing and repairs look like

• Your engineer understands  both  the refrigerant circuit  and  the hydronic side.
• F-Gas work is only done by  properly certified personnel, as required by UK regulations.
• Each service includes  real checks and measurements, not just a visual once over.
• Fault-finding starts with  data and symptoms, not swapping parts at random.
• You get a clear  report and recommendations, not just “all fine” on a job sheet.
• The aim is a system that is  quiet, stable and efficient, not just one that runs.

What we actually do on a service visit

Exact checks vary by make and model, but a Wellington Wallace Renewables service typically covers:

Visual and safety checks

• Condition of outdoor and indoor units.
• Mounting, pipe insulation, brackets and isolation valves.
• Any obvious signs of water leaks or refrigerant oil staining.

System pressures, flows and temperatures

• Heating and hot water system pressure.
• Flow and return temperatures on heating and cylinder circuits.
• Delta-T across key circuits.
• Basic verification that sensors are reading sensibly.

These numbers tell us if the system is moving heat in the way it was designed to.

Filters, strainers and dirt separators

• Clean or replace strainers/filters as appropriate.
• Check magnetic filters for sludge build-up.
• Confirm valves are fully open where they should be.

Poor flow from blockage is one of the most common causes of noisy, inefficient systems.

Refrigerant circuit and F-Gas responsibilities

Where we’re dealing with the sealed refrigerant circuit, we follow:

• Leak detection and inspection rules set out under F-Gas guidance.
• Manufacturer procedures for pressure, superheat/subcool readings where needed.
• Correct recovery and handling if any work is needed on the circuit.

Not every service requires gauges and deep refrigerant work, but when it does, we treat it as safety critical.

Controls, curves and operations

We’ll:

• Review schedules, setpoints and any room stats in use.
• Check weather compensation and flow temperature targets.
• Look at how often backup heaters or immersions are being called.

The aim is to line up  controls, design and real world usage  so the system isn’t constantly fighting itself.

Documentation and recommendations

You’ll get:

• A short written summary of what we found.
• Any settings we changed (with reasons).
• Recommended follow up work (e.g. radiator upgrades, insulation, additional valves).

Repairs and fault-finding: how we approach “problem” systems

Most “problem” systems fall into one of three camps:

1. A genuine component fault: pump, sensor, fan, board.
2. A design issue: undersized emitters, missing components, bad hydraulics.
3. A setup or control issue: wrong parameters, poor wiring, odd zoning.

Our process is:

• Start with symptoms and history: what the system does, when, and how long it has been happening.
• Look at installation layout and pipework, not just the box.
• Pull error histories and logs where available.
• Rule out obvious design or flow issues before blaming the heat pump.

Because Wellington Wallace Renewables came out of a manufacturer service background, we treat repairs more like medical diagnostics than guesswork.

Common mistakes we see on “serviced” systems

• “Service” limited to a visual check and a note saying “no leaks”.
• No one ever checks flow rates, delta-T or temperature readings.
• Filters never cleaned because they’re in awkward spots.
• F-Gas work carried out by people with no certification or paperwork.
• Error codes repeatedly reset without investigating the root cause.
• Parameters changed randomly “to see what happens”.

If you’ve been told “that’s just how heat pumps are” when the system is noisy, expensive and unreliable, it probably isn’t the full story.

DIY checks vs when to call an engineer

Reasonable DIY checks

• Check system pressure on your heating side and top up if you’ve been shown how.
• Keep outdoor unit clear of debris, leaves and snow.
• Check and clean user-accessible filters if your handover covered it.
• Note down error codes and when they occur.

When you definitely need a professional

• Repeated lockouts or trips.
• Any suspicion of a refrigerant leak (unusual noises, visible oil, strong smells).
• Constant use of backup heaters or immersion to keep up.
• Loud mechanical noises from the outdoor unit.
• Very uneven heating, cold rooms or radiators that never get warm.

For anything involving refrigerant, electrics, or major parameter changes, use a qualified engineer. UK F-Gas guidance is clear that certain tasks must only be carried out by certified personnel; it’s about safety, performance and legal compliance.