Pricing and quoting, 29 October 2026
How to price a boiler installation: what to include
Price a boiler installation by adding the boiler and flue at cost plus your markup, the system clean and filter, the controls the regulations require, labour in engineer-days, disposal, and the cost of notifying the work. In England, a replacement gas boiler must reach 92% ErP efficiency, and a combi needs one extra efficiency measure. Standard VAT is 20%.
What should a boiler quote include?
Everything between the old boiler coming off the wall and the client holding a commissioned, registered installation. The boiler is one line; the rest is where margin goes missing.
How much labour should you allow?
Count engineer-days from the survey. A like-for-like combi swap in the same position is usually the quickest job you'll do. Moving the boiler, converting from a system with a cylinder, or rerouting the flue adds a day or more each. Remember the time you spend on the day you don't see: collecting the boiler, disposing of the old one, filling in the commissioning checklist and registering the work.
A worked example: combi-to-combi swap
Combi swap, same position, three-bed semi in England
Like-for-like replacement of a 15-year-old combi in the kitchen. Standard horizontal flue, chemical clean, magnetic filter, and smart controls with automation and optimisation to meet the combi rule. Engineer day rate £320 (labour, overheads and margin), materials marked up 20%. Equipment prices are illustrative; use your merchant price.
| Combi boiler£1,150 at cost + 20% | £1,380 |
| Flue kit, magnetic filter, chemical cleanser, inhibitor, fittings£240 at cost + 20% | £288 |
| Smart thermostat with automation and optimisation£160 at cost + 20% | £192 |
| Labour: remove old boiler, fit and connect new1 engineer × 1.5 days × £320 | £480 |
| Labour: clean, flush, commission, handover1 engineer × 0.5 day × £320 | £160 |
| Disposal of old boilerwaste charge | £30 |
| Notification and adminGas Safe notification fee and paperwork, illustrative | £15 |
| Price before VAT | £2,545 |
| VAT at 20%£2,545 × 20% | £509 |
| Price to the client | £3,054 |
Price warranty registration time in too. Manufacturer warranties often depend on a filter, inhibitor and registration within a set period, so the chemical clean and filter aren't optional extras on most installs. Add your standard material markup consistently so every quote earns the same.
What do the efficiency rules require?
In England, Approved Document L sets a minimum efficiency of 92% (ErP) for a gas boiler on a wet heating system in an existing dwelling. When the boiler is a gas combi, at least one extra energy efficiency measure is required. These rules started as Boiler Plus in April 2018.
Add one of: flue gas heat recovery, weather compensation, load compensation, or a smart thermostat with automation and optimisation. Put it on the quote as its own line so the client sees why.
Time and temperature controls are required on gas and oil systems. Check the boiler's ErP efficiency on its data sheet.
The Boiler Plus combi rule applies in England. Wales, Scotland and Northern Ireland have their own building regulations, so check the current guidance before you price.
Do you need to notify building control?
Yes, in England and Wales, through your registration. Replacing a boiler is building work, and the usual route is to have it done by an installer registered with a competent person scheme. Gas Safe Register's guidance says the registered business that fitted the appliance must notify the work within 30 days of completion, and Gas Safe then sends the client a Building Regulations Compliance Certificate. Gas Safe's consumer guide notes this doesn't apply in Scotland, so check local rules there and in Northern Ireland.
Rules and schemes differ between the four nations, so make sure your quote template follows the nation you work in.
What VAT do you charge on a boiler installation?
The standard rate, 20%, for most boiler installs. GOV.UK lists energy-efficient boilers among the products that carry 20% VAT. A reduced rate can apply only where the installation is funded by a qualifying grant, under VAT Notice 708/6. Some heating controls installed in homes can qualify for the 0% energy-saving rate on their own; if a job mixes zero-rated and standard-rated items, ask your accountant how to split it.
How do you follow up a boiler quote?
On a set timetable, in writing. One gas firm we spoke to, with three engineers and two subcontractors, chased boiler quotes at 7 days and again at 30 days. Boiler quotes go to clients comparing two or three installers, so a quick, polite follow-up with the quote attached is often what wins it.
Where Nexley fits
Nexley is the AI back office for UK trade firms: five AI assistants run your tenders, quotes, buying, scheduling and invoicing. It connects to the tools you already work in, you run it all from WhatsApp, and you approve everything. £799 a month.
For boiler installs, your engineer sends Nexley the survey photos and a voice note on WhatsApp. Nexley prices it from your boiler and parts list, day rate and standard lines, adds the controls line a combi needs in England, drafts the quote and sets the 7 and 30 day follow-ups. You check and approve each one before it goes.
Common questions
How long does a combi swap take?
A like-for-like swap in the same position is commonly done in a day by one engineer. Moving the boiler, converting a system or rerouting the flue adds time. Price from your survey, not from a fixed rule.
Should I include a power flush on every quote?
Include a clean that suits the system. A heavily sludged system needs a power flush; a cleaner one may need only a chemical clean and filter. Check the boiler manufacturer's warranty conditions, which often require cleaning and a filter.
Who sends the Building Regulations Compliance Certificate?
In England and Wales, Gas Safe Register sends it to the client after you notify the work through your registration, which should happen within 30 days of completion.
Can I quote a boiler without a site visit?
With good photos of the boiler, flue terminal, gas meter, pipework and the room, many installers do. State your assumptions on the quote, such as flue length and gas pipe size, so changes can be priced as variations.
Sources
- GOV.UK: Approved Document L, Volume 1: Dwellings
- GOV.UK: Boiler Plus factsheet
- Planning Portal: Boilers and heating, building regulations
- Gas Safe Register: Notification of gas work in England and Wales
- Gas Safe Register: The consumer guide to gas boilers
- GOV.UK: VAT on energy-saving products
- GOV.UK: Energy-saving materials and heating equipment (VAT Notice 708/6)
Every rule, rate and date above was checked against these sources on the date shown at the top.
Topic: Pricing and quoting
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