Buying a Boiler Online: Prices and Installation Costs

To compare boiler installation quotes, start with each installed price including VAT and add only the required work it excludes. Then compare the totals for the same boiler model and scope. This manual worksheet helps you organise written quotes; for a price tailored to your property, use iHeat’s new boiler quote service.

If you are still setting an initial budget, our new boiler costs guide explains the rounded iHeat installation benchmark and why swaps, conversions and cylinder replacements have different requirements.

1. Write down the job you are comparing

Before adding prices, give each installer the same brief. Record your existing boiler type, whether it stays in the same position, and whether you want to retain, replace or remove a hot-water cylinder. Include any change in hot-water demand, such as an additional shower.

A quote to replace a system boiler while keeping its cylinder cannot be compared directly with a package that supplies a new cylinder too. Similarly, a regular-to-combi conversion includes work that a straightforward combi replacement may not need.

• Boiler: exact make, model and output, with the installer’s explanation of suitability.

• Location: existing position or relocation, including the proposed flue route.

• Hot water: cylinder retained, replaced or removed; any agreed capacity change.

• Controls: exact thermostat, radiator valves and zones.

• Other work: known access, pipework, electrical or making-good requirements.

2. Copy this comparison worksheet

Use a separate column for each written quote. Enter £0 extra where an item is already included, the quoted additional price where it is excluded, and not confirmed where you still need an answer. An unknown cost is not zero. Copy the table into your notes or a spreadsheet to fill it in.

Comparable installation total = VAT-inclusive installed package price + required excluded extras including VAT.

Your chosen cash total = comparable installation total + optional upgrades you select.

If a price is stated excluding VAT, ask the installer to confirm the VAT-inclusive amount and applicable treatment before entering it. Do not add VAT again to an inclusive price, or add labour again when the package already includes installation.

3. Check the items most easily missed

Flue and access: confirm extensions, a vertical route, roof access or scaffolding where needed. The lowest headline quote may assume an installation arrangement that does not suit your property.

Pipework: ask what alterations are included after assessment. A gas-pipe upgrade is installation-specific, so do not add a standard allowance without a confirmed requirement and price.

Controls: check the exact product. Wireless operation does not necessarily mean app control, and additional zones or subscriptions may be separate.

Cleaning: record whether the quote includes a chemical clean, power flush or another specified method, plus inhibitor and any filter. These descriptions do not all refer to the same service.

Finishing: confirm old-equipment removal, repairs to openings and decoration. If another trade must finish the work, obtain its price separately and add it once.

4. Worked example: the cheaper headline is not always the cheaper job

These figures are illustrative, not customer records or current iHeat offers. Both examples assume the same boiler and agreed installation scope, and all amounts include VAT.

Quote A totals £2,600 + £150 + £250 = £3,000. Quote B is £100 lower for the same work. If you later choose a £200 optional upgrade available at that price with either package, your chosen totals become £3,200 and £3,100. Keep that choice separate from the work needed to complete the installation.

5. Compare quality, cover and timing alongside price

Two matching totals can still buy different packages. Record the manufacturer’s warranty, registration and servicing conditions, and the installer’s workmanship cover. Check the model and controls rather than relying on the brand name alone.

Ask for the installation date, expected duration and likely interruption to heating and hot water. Confirm who to contact if a problem arises after installation. If an item remains unpriced, resolve it before treating the total as fixed.

6. Keep finance and future costs separate

For finance, record the deposit, total repayments, fees and total payable from the agreement. Compare that full amount with the cash price; do not add the cash price to the repayments as though you pay both. Check whether any quoted total payable already includes the deposit.

Keep annual servicing and an optional personal contingency in separate budget lines. A contingency is money you set aside, not an installer’s charge or evidence that the quote will rise. Energy savings also belong in a separate running-cost estimate; they do not reduce the installation invoice.

Before you accept a quote

• Confirm the exact model and assessed suitability for your home.

• Get inclusions, exclusions and the total including VAT in writing.

• Resolve every “not confirmed” item in your worksheet.

• Check how changes to the agreed work must be approved.

• Keep the quote, payment terms, warranty conditions and installation schedule.

For more detail on installation scenarios and the evidence behind the price benchmark, return to our UK new boiler costs guide. When you have your property details ready, request a quote for the work you actually need.

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