Boiler Annual Service Contract vs Pay-As-You-Go: What London Landlords Actually Save

The Core Question: Contract or One-Off?

Every London landlord with a gas boiler faces this choice: sign a monthly contract with British Gas, Homeserve, or a local provider, or simply book an annual Gas Safe service and CP12 when they fall due. The answer depends on the age of your boilers, your portfolio size, and how much risk you want to carry.

What an Annual Service and CP12 Costs in London

A standalone annual boiler service combined with a Landlord Gas Safety Record (CP12) from a Gas Safe registered engineer in London typically costs between £90 and £160 for a single boiler. Central London and zones 1–2 attract the higher end of that range; outer London boroughs tend to sit at £90–£120. If you book a portfolio of four or more properties with the same engineer, many will negotiate a per-property rate of £80–£100.

If the boiler requires a repair on top of the service, that is a separate call-out. A straightforward replacement of a diverter valve or pump might cost £150–£300 including parts. A heat exchanger or PCB replacement on an older boiler can run £400–£600 or more, at which point the engineer may recommend replacement instead.

What Boiler Cover Contracts Typically Cost

Landlord-specific boiler cover contracts in London range from roughly £12 to £30 per month per property, depending on the provider and the tier selected. At £20 per month that is £240 per year — already £80–£150 more than a standalone service and CP12 on a younger, reliable boiler.

Most standard contracts include:

• Annual boiler service and Gas Safety Record
• Unlimited call-outs for boiler breakdowns
• Parts and labour for covered repairs

Premium tiers add central heating cover (the pipework, pump, radiators, zone valves) and sometimes plumbing and drainage. These can run £35–£50 per month per property.

What Contracts Typically Do Not Cover

Reading the exclusions is critical. Common exclusions in standard boiler-only contracts include:

• Boilers over 15 years old (some providers cap at 7 years old)
• Pre-existing faults identified at the first service
• Powerflush or system cleaning (presented as a prerequisite before cover begins)
• Magnetic system filter replacement or cleaning
• Radiators, valves, pipework (unless on a heating system tier)
• Boilers requiring parts that have been discontinued by the manufacturer
• Cosmetic damage or damage caused by scale in hard water areas (relevant in London)

London's hard water is a significant practical issue. Scale buildup in heat exchangers is a common cause of boiler failure, and many policies classify it as a maintenance issue rather than a covered breakdown. Check whether the policy covers scale-related damage explicitly.

The Break-Even Calculation

A boiler service contract makes financial sense if you would otherwise expect repair costs in excess of the annual premium minus the cost of a standalone service. On a modern boiler (under 8 years old) in good condition, the probability of a significant repair in any given year is relatively low, and a standalone service likely wins on pure cost.

Where contracts earn their value:

• Boilers aged 8–15 years, where reliability declines
• Landlords with a single property who cannot afford an unexpected £400–£600 repair bill
• Landlords who value the certainty of a fixed monthly cost and unlimited call-outs
• Properties in central London with tenants who will escalate complaints quickly, where fast response times from a major provider matter

Portfolio Landlords: The Self-Insurance Approach

Landlords with five or more properties in London frequently find that self-insuring across the portfolio is cheaper than individual contracts. The logic: if each property has a 10–15% chance of a significant boiler repair in a given year, and you have ten properties, you expect one or two repairs annually. Setting aside £150 per property per year into a maintenance reserve covers the expected cost, and the reserve accumulates in years where repairs are below average.

This requires discipline — the reserve must actually be set aside, not spent — but for an established portfolio it consistently outperforms monthly contract costs over a five-year horizon.

What to Look For If You Do Sign a Contract

If you decide a contract is right for your situation, check these points before signing:

• Response time guarantee: next-day or within 24 hours is the minimum for a rental property
• Whether the CP12 is included or an additional charge
• Excess per call-out (some budget plans charge £50–£100 per visit)
• Whether parts are covered with no cap, or whether there is a parts cap per year
• The age limit on covered boilers
• Hard water and scale exclusions
• Cancellation terms — some contracts lock in for 12 months with a penalty for early exit