Heat Pump Warranty Traps: What the Small Print Really Says

A heat pump warranty of 5, 7, or even 10 years sounds reassuring. But what does it actually cover? What can void it? And what are the hidden conditions that could leave you paying for repairs you thought were covered? We have read the warranty documents from every major heat pump brand sold in the UK and identified the most common traps, exclusions, and conditions that homeowners need to know about. Understanding your consumer rights starts with understanding what the warranty actually says.

Types of Heat Pump Warranty

There are three distinct warranty types that apply to a heat pump installation, and confusing them is a common source of problems.

The manufacturer warranty covers defects in the heat pump itself — compressor failure, circuit board faults, refrigerant leaks from factory joints. It does not cover problems caused by poor installation, incorrect commissioning, or lack of maintenance. That is the installer's responsibility.

The installer workmanship warranty covers problems arising from how the system was installed — leaking pipe joints, incorrect wiring, undersized radiators, poor commissioning. If your installer is MCS-certified, this warranty is insurance-backed, protecting you even if the installer goes bust.

Warranty Comparison by Brand

Source: Manufacturer warranty documentation, current as of March 2026. Terms may change — always verify with the manufacturer directly.

Trap 1: The Servicing Requirement

This is the most common warranty trap. Almost every manufacturer requires annual servicing by a qualified engineer as a condition of the warranty. If you miss a service — even one — the manufacturer may refuse a warranty claim.

The severity varies by brand:

• Strict: Some brands void the entire warranty if a single annual service is missed
• Moderate: Some void the warranty only for issues that the missed service would have detected or prevented
• Lenient: A few brands treat servicing as "recommended" rather than "mandatory" but may still use it as grounds to dispute a claim

Annual servicing typically costs £100-200. Over a 7-year warranty period, that is £700-1,400 — a significant cost, but far less than a compressor replacement (£1,500-3,000) that would not be covered without valid service records.

Protection tip: Set up a recurring annual service with your installer or a local MCS-certified engineer. Keep all service records, receipts, and certificates in a dedicated folder.

Trap 2: Installation Quality Exclusions

Manufacturer warranties typically exclude any damage or malfunction caused by incorrect installation. This includes:

• Incorrect refrigerant charge (too much or too little)
• Wrong pipe sizing or lengths
• Inadequate water flow through the system
• Incorrect electrical connection
• Poor positioning causing airflow restriction
• Installation by non-qualified personnel

This is why installer quality matters enormously. A bad installer does not just cause short-term problems — they can void your manufacturer warranty entirely, leaving you exposed for the full 20-year lifespan of the equipment.

Protection tip: Always use an MCS-certified installer. The MCS commissioning certificate serves as evidence that the installation was carried out correctly, protecting your manufacturer warranty.

Trap 3: Parts Only vs Parts and Labour

A "5-year warranty" sounds comprehensive. But does it include the cost of the engineer's visit to diagnose and fit the replacement part? Not always.

A parts-only warranty means the manufacturer supplies the replacement component free of charge, but you pay for the engineer's time to visit, diagnose, and install it. A typical warranty repair visit costs £100-250 for labour — sometimes more if the fault is complex.

A parts and labour warranty covers everything — the replacement part and the engineer's time. This is obviously better, but some brands only offer it through their approved installer network or at a premium price.

Protection tip: When comparing quotes, ask specifically whether the warranty includes labour. Factor in potential labour costs over the warranty period when comparing "parts only" vs "parts and labour" brands.

Trap 4: Coastal Corrosion Exclusions

If you live within 2 km of the coast, this trap is critical. Most manufacturer warranties exclude corrosion damage unless a coastal-rated model (with anti-corrosion coating) was installed. If a standard model is installed in a coastal zone, corrosion damage to the heat exchanger is not covered — even if the installer should have specified the coastal version.

Heat exchanger replacement costs £800-1,500. A coastal coating adds £150-500 to the purchase price. The maths is obvious.

Protection tip: If you live within 5 km of the coast, insist on a coastal-rated unit and confirm in writing that corrosion damage is covered under warranty.

Trap 5: Power Surge Exclusions

Most manufacturer warranties exclude damage caused by power surges, lightning strikes, or electrical supply problems. Heat pump circuit boards are sensitive electronics — a single power surge can destroy the main PCB, costing £500-1,200 to replace.

Rural properties with overhead electrical supplies are particularly vulnerable to power fluctuations and lightning-induced surges.

Protection tip: Install a surge protector on the heat pump's electrical supply. Cost: £50-100. Some installers include this as standard; others do not. Ask specifically whether surge protection is included in your quote.

Trap 6: Warranty Registration Deadlines

Several brands require warranty registration within a specific period after installation — typically 30-90 days. If you miss the deadline, you may receive only the basic warranty (e.g., 2 years) instead of the extended warranty (e.g., 5-7 years).

Some installers handle warranty registration as part of the MCS process. Others leave it to the homeowner. Check your handover documentation — if there is a warranty registration form, complete it immediately.

Protection tip: Ask your installer whether they will register the warranty on your behalf. If not, find out the deadline and register immediately after installation.

Transferring Your Warranty

If you sell your property, the heat pump warranty is a valuable asset for the buyer — and an important selling point. Most manufacturer warranties are transferable, but the process varies:

• Automatic transfer: Some brands transfer automatically with the property — no action needed
• Notification required: Most brands require you to notify them of the change of ownership within 30 days
• Non-transferable: A few brands restrict the warranty to the original purchaser only

When selling, include the warranty documentation, service records, and MCS certificate in the handover pack for the buyer. This also helps with the property value argument for heat pumps.

How to Protect Yourself

1. Read the warranty before signing the contract — ask for the full warranty document, not just a summary
2. Use an MCS-certified installer — protects your manufacturer warranty and gives you insurance-backed workmanship cover
3. Register the warranty immediately — do not miss the deadline
4. Keep annual service records — every service, every receipt, every engineer's report
5. Install surge protection — cheap insurance against expensive circuit board damage
6. Specify coastal-rated models near the coast — protect against corrosion exclusions
7. Pay by credit card — Section 75 protection provides an additional safety net
8. Keep all documentation safe — MCS certificate, commissioning report, warranty, service records

Frequently Asked Questions

Do I need annual servicing for the warranty?

Almost always yes. Missing services can void your warranty — the severity depends on the brand. Budget £100-200/year for annual servicing.

What voids a warranty?

Missing services, incorrect installation, DIY modifications, using non-genuine parts, coastal corrosion on standard models, and power surge damage without surge protection.

Are labour costs covered?

It varies by brand. Some offer parts and labour; others cover parts only (you pay £100-250 for the engineer's visit). Check before buying.

Can I service it myself?

Basic cleaning yes, but the annual warranty service must be by a qualified engineer. Self-servicing does not satisfy the warranty requirement.

What if my installer goes bust?

The manufacturer warranty continues — you deal with the manufacturer directly. The workmanship warranty is covered by insurance-backed protection if the installer was MCS-certified.

Is the warranty transferable?

Usually yes, but you typically need to notify the manufacturer within 30 days of the property sale.