36+ years. 1,000+ installations. Up to 12-year guarantees.
When your boiler decides to call it a day, the first thing you think about isn't technical specs — it's the price tag. You want a straight answer, not a sales pitch. At Boilers On-Demand (Coventry Plumbing Ltd), we've been serving Sussex and Surrey since 1988. We don't do call centres, and we don't do "hidden" extras.
If you're looking for a new boiler installation in Sussex, here is the no-nonsense truth about what you're likely to pay in 2026 and why.
1. The Real-World Ballpark Figure
Let's get the big question out of the way. A typical boiler replacement cost in the UK for 2026 generally sits between £2,000 and £4,000.
For a straightforward combi boiler installation cost, where we swap an old unit for a new one in the same spot, you're looking at a median price of roughly £2,300 to £3,200. This covers a high-quality boiler, professional labour, and the necessary safety certificates. If you're being quoted £6,000 for a basic swap by a national giant, you're paying for their TV adverts, not your heating.
2. Why Sussex and Surrey Prices Differ
Living in the South East has its perks, but cheap labour isn't usually one of them. Because we are local — covering Horsham, Steyning, Billingshurst, and Petworth — we keep our overheads low. However, generally, a gas safe engineer in Sussex will have higher operating costs than one in the North. When you see national "average" prices online, remember they often include lower-cost regions. In Sussex and Surrey, expect to be at the mid-to-upper end of national averages for quality work.
3. Combi Swap vs. System Conversion
The type of system you have dictates the final bill.
- Simple Swap: Replacing an old combi with a new one is the fastest and cheapest route.
- System Conversion: If you are moving from an old-fashioned regular boiler (with a water tank in the loft) to a modern combi, the boiler installation cost increases. You're looking at £3,500 to £5,000+ because we have to remove tanks, redirect pipework, and ensure your radiators can handle the new pressure.
4. Choosing the Right Brand (Vaillant, Baxi, Glow-worm)
We don't fit "budget" boilers that break in three years. We specialise as Vaillant boiler installers, and we also recommend Baxi and Glow-worm.
- Budget Models: Can save you £400 upfront but often cost more in repairs.
- Premium Models (Vaillant/Baxi): These are the gold standard. They are quieter, more efficient, and come with much longer manufacturer guarantees. We believe in doing the job properly the first time so you don't see us again until your annual service.
5. Never Compromise on Gas Safe Registration
This isn't a "nice to have" — it's the law. Every single one of our engineers is Gas Safe registered (No. 575142). When comparing quotes, don't just look at the bottom line. Ensure the person entering your home is qualified to be there. We always encourage our customers to check our ID cards at the door. Your family's safety is worth more than a £100 saving on a "cash-in-hand" job.
6. The "Hidden" Extras: Flues and Filters
A "cheap" quote often leaves out the essentials that keep your boiler running for a decade. A proper installation should include:
- Magnetic Filters: These catch metallic debris before it clogs your brand-new boiler.
- System Flush: We clean out the old "sludge" from your radiators.
- Flue Requirements: Modern regulations might mean your old flue (the exhaust pipe) needs upgrading to a different position or material.
7. Same-Day Installation (The On-Demand Way)
We know that being without hot water is a nightmare. That's why we aim for same-day installation on the vast majority of our boiler replacements. Because we focus on Sussex and Surrey, we don't spend half the day in traffic. We arrive punctual, stay until the job is done, and leave your house as clean as we found it.
8. Financing Your Comfort
We understand that a new boiler is a significant investment. You shouldn't have to choose between a warm home and your savings. We offer flexible finance options to help manage the cost. Whether you want to pay upfront or spread it out, we provide a transparent breakdown with no hard sell.
9. Long-Term Guarantees vs. Short-Term Savings
A "cheap" installer might give you a 12-month "man-with-a-van" warranty. Because we are accredited installers for brands like Vaillant, we can offer manufacturer guarantees of up to 12 years. That is over a decade of peace of mind. If something goes wrong with the unit, the manufacturer covers the parts and labour. That's the value of using an established local expert over a fly-by-night contractor.
10. Our Price Beat Guarantee
We aren't the biggest company in the South East — just the most trusted. We pride ourselves on honest, local service. If you have a written quote from another Gas Safe registered company for the same high-quality boiler and installation standards, we will beat it.
We want to make sure every homeowner in our community has access to safe, efficient heating without being overcharged.
Summary of Costs (Sussex & Surrey 2026)
| Service Type | Estimated Cost Range |
|---|---|
| Standard Combi-to-Combi Swap | £2,300 – £3,200 |
| Boiler Conversion (System to Combi) | £3,500 – £5,000+ |
| Moving Boiler to New Location | Add £800 – £1,200 |
| Premium Smart Controls Upgrade | Add £150 – £350 |
Frequently Asked Questions
- How much does a new boiler cost in Sussex in 2026?
- A new boiler in Sussex typically costs between £2,000 and £4,000 installed. A straightforward combi-to-combi swap usually falls between £2,300 and £3,200, covering the boiler, professional labour, and the necessary safety certificates.
- Why do boiler prices differ in Sussex and Surrey?
- Operating costs in the South East are higher than in many other parts of the UK, so national average prices can be misleading. In Sussex and Surrey, expect to be at the mid-to-upper end of national averages for quality work.
- How much does it cost to convert from a regular boiler to a combi?
- A system conversion typically costs £3,500 to £5,000 or more, because it involves removing tanks, redirecting pipework, and making sure your radiators can handle the new pressure.
- What should a proper boiler installation quote include?
- A complete quote should include a magnetic filter, a full system flush, and any flue upgrade your installation requires. If these are missing, ask why — they are essential for your guarantee to remain valid.
- Do you offer a price beat guarantee?
- Yes. If you have a written quote from another Gas Safe registered company for the same high-quality boiler and installation standards, we will beat it.
Why Boilers On-Demand?
We've been doing this since 1988. We've seen every type of pipework, every quirky Sussex cottage layout, and every boiler error code in the book.
- Local Experts: Serving Sussex and Surrey for 36+ years.
- Certified: Gas Safe Registered (575142).
- Reliable: 1,000+ boilers installed with a focus on cleanliness and punctuality.
- Read more about our history, or see our boiler servicing and repairs options for your current system.
No hard sell. Just a straight conversation.
If your boiler is acting up or you're worried about the cost of a replacement, give us a call. We'll give you an honest assessment and a fair price.