Boiler Replacement
in Watford &
Hertfordshire
A new A-rated boiler fitted properly, at a fixed price, by the same engineer who quoted you — with up to a 10-year manufacturer warranty and a written 12-month workmanship guarantee.
What boiler replacement actually covers
What it is
A full boiler replacement covers the boiler, a new flue, a system filter, isolation valves, condensate route and all electrical connections — commissioned to manufacturer specification and notified to Building Control under our Gas Safe registration (No. 212325).
Who it's for
Homeowners with a boiler over 10 years old, anyone with rising gas bills, landlords upgrading rental properties, or households whose boiler is beyond economic repair. If a fault costs more than a third of a replacement, you're usually better off changing it.
When you need it
Ideally before winter, before you're forced into an emergency swap at short notice. Signs it's time: repeated breakdowns, low pressure that keeps returning, banging or kettling, cold radiators at the top of the house, or an F-code that keeps coming back.
Why professional help matters
Boiler swaps look simple until they aren't. A new boiler installed onto a dirty, unbalanced system will fail early and void the warranty. Every install we do includes a system flush, filter, correct gas rate, tightness test and full commissioning paperwork — not just a like-for-like swap.
The cost of leaving it
Putting off a replacement is expensive. An inefficient boiler quietly burns money every month, and a boiler on borrowed time almost always fails on the coldest weekend of the year.
What can go wrong
- An old non-condensing boiler can be 20–30% less efficient than a modern A-rated unit — that's real money on every gas bill.
- A failed heat exchanger or gas valve on an older boiler is often uneconomic to repair and can leave you without heat or hot water for days waiting on parts.
- Emergency replacements cost more, restrict brand choice, and rarely allow time to size the boiler properly for your home.
- A boiler that hasn't been notified to Gas Safe / Building Control can jeopardise a house sale and your building insurance.
Common mistakes we see
- Choosing the cheapest quote without checking the installer is Gas Safe registered and manufacturer-accredited.
- Accepting a like-for-like swap without a system flush — this alone can void a 10-year warranty.
- Oversizing 'to be safe' — an oversized combi short-cycles, wastes gas and wears out faster.
- Skipping a system filter and inhibitor to shave £100 off the quote, then paying for a powerflush 18 months later.
Our process
A clear, repeatable system — the same on every job, whether you're a homeowner or a landlord with a portfolio.
- 01
Free on-site survey
Matt visits, measures gas rate, checks the flue route, hot water demand and existing pipework.
- 02
Fixed written quote
Emailed the same day (or within 24 hours). Boiler brand and model, warranty length and all inclusions listed line by line.
- 03
Install day
Usually 1 day for a straight swap, 2 days for a system change. Dust sheets down, floors protected, area left cleaner than we found it.
- 04
Commissioning & testing
Gas tightness test, correct gas rate to manufacturer spec, full flue gas analysis, controls set up and every radiator balanced.
- 05
Registration & guarantee
Notified to Gas Safe and Building Control, manufacturer warranty registered in your name, Benchmark logbook completed and handed over.
What you get
Fixed price, no surprises
The price you're quoted is the price you pay. If we hit something unexpected, we call before spending your money.
Up to 10-year warranty
Full 10 years on Vaillant as an Accredited Installer. Up to 10 years on other major brands.
Lower bills from day one
Correctly sized, correctly commissioned. Most customers see a meaningful drop in gas usage in the first billing cycle.
Cleaner, quieter home
New system filter, magnetite removed, radiators balanced — no more cold spots or kettling.
Safe & compliant
Notified under our Gas Safe registration. Building Control certificate provided. £5m public liability cover.
One engineer, start to finish
Matt (or Matt and his son) quotes, installs and commissions. No subcontractors, no handovers.
Recent boiler replacement work
Photos from real jobs completed by Matt and the Premier Heating team.
In detail
We fit all major boiler brands — combi, system and regular (heat-only). As an Accredited Vaillant installer we can register the full manufacturer 10-year warranty in your name.
Combi vs system vs regular
A combi suits most 1–3 bathroom homes with a single shower running at a time and no need for a cylinder. A system boiler with an unvented cylinder is the right call for larger homes, multiple bathrooms or households that want strong flow at two showers at once. Regular (heat-only) boilers make sense where you're keeping a cold-water tank and cylinder for a specific reason. We size on hot water demand and radiator heat loss — not on the sticker of the old boiler.
Vaillant Accredited installation
Vaillant only allows their Accredited Installers to register the full 10-year manufacturer warranty. That covers parts and labour on the boiler for a decade, provided it's serviced annually. It's a genuinely different product from the shorter warranties available through non-accredited fitters.
System flush and filter as standard
Every replacement includes a hot chemical flush (or a full powerflush where the system needs it), a magnetic system filter (usually Adey or Fernox) and a fresh dose of inhibitor. This protects the new heat exchanger, keeps efficiency high and is a manufacturer requirement for the long warranties.
Flue routing and controls
We cover horizontal, vertical and plume-management flue kits, and can move the boiler location where the current position causes noise, plume or access issues. Smart controls (Tado, Hive, Nest, Vaillant vSMART) can be added at install for weather compensation and load compensation, which further cuts gas usage.
Landlords and portfolios
For landlords we can bundle the replacement with a CP12 landlord safety certificate and set up an annual service schedule. We're used to working around tenants and can coordinate access directly.
Frequently asked questions
How much does a new boiler cost, fitted?
Our new boiler + flue + system filter installations start from £1,975 fitted. The exact price depends on the boiler brand and model, whether you're changing type (e.g. system-to-combi) and the flue route. Every quote is fixed, written and free.
How long does a boiler replacement take?
A straight combi-for-combi swap in the same location is usually done in a day. Converting from a system boiler to a combi, or relocating the boiler, is typically 1.5–2 days. We'll tell you which on the survey.
What warranty do I get?
Up to 10 years' manufacturer warranty on all major brands, and the full 10-year Vaillant warranty as an Accredited Installer. On top of that, all of our workmanship is guaranteed for 12 months.
Do I need a powerflush before a new boiler?
Not always. Every install includes at minimum a hot chemical flush and a new magnetic filter. If the system water is heavily contaminated we'll recommend a full powerflush — priced separately — to protect your new warranty.
Do you take a deposit?
No deposit is required on most installs. Payment can be by card, cash or bank transfer on completion.
Do you offer finance?
Not at this time. We accept card, cash and bank transfer on completion of the work.
Do you cover my area?
Yes — we cover Watford, Northwood, Rickmansworth, Pinner, Bushey, Hatch End, Stanmore, Middlesex and Greater London. If you're nearby but not listed, please call.
Will you register the boiler and notify Building Control?
Yes. Every install is notified under our Gas Safe registration (No. 212325) and the manufacturer warranty is registered in your name. You'll receive a Benchmark logbook and Building Control certificate.
Can I keep my old thermostat or should I upgrade?
You can keep a working thermostat, but modern smart controls (Tado, Hive, Nest, Vaillant vSMART) with weather/load compensation can noticeably reduce gas usage. We'll price both options on the quote.
Related services
Areas we cover
Based in Watford, serving Hertfordshire and Greater London.
Need something not listed? Get in touch.
Ready for a warmer home and lower bills?
Free on-site quote, fixed price, no call-out fee. Matt personally answers every enquiry.