Boiler Conversion Cost in South Wales (2026 Guide)
If you’re looking for clear, honest information about boiler conversion costs.
This guide breaks down everything you need to know — real 2026 prices, what affects the cost, optional upgrades, and expert insights from our Gas Safe engineers.
Blue Flame has based this on over 10 years of real installation data across South Wales, helping homeowners make confident decisions.
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Key takeaways
- Typical boiler conversion cost in South Wales: £3,000–£4,200
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Cost varies depending on the type of conversion (e.g. regular → combi, system → combi, back boiler → combi)
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Conversions usually take 2 days due to extra pipework and removal of tanks or cylinders
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Ideal when upgrading older heating systems to modern combi or system boilers
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FREE Silver Cover (12 months) included with every installation
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Blue Flame Warranty™ included as standard (up to 5 years in-house)
Why Homeowners Choose Blue Flame for your Boiler Conversion
Award-winning back boiler replacement experts trusted across South Wales. Fixed-price quotes, expert engineers, and full aftercare with every installation.
Fast Installation Turnaround
Most boilers installed within 24–48 hours. Same-day surveys available in many South Wales areas.
Fixed-Price Boiler Quotes
Transparent, all-inclusive prices with no hidden extras. Fully guaranteed fixed installation price.
Gas Safe Registered Engineers
Fully qualified, insured, and legally certified. Safe, compliant installations every time with trusted engineers.
Guaranteed Aftercare & Support
Includes warranty registration, service reminders, fast support — plus FREE Silver Cover for 12 months.
FREE Boiler Cover Included (Worth £143)
12 Months of Silver Cover with Every New Installation.
Your installation price already includes your first-year service, safety checks, reminders, and full aftercare — at no extra cost.
✔ Annual Boiler Service Included
Your full boiler service completed automatically within the first 12 months.
✔ Priority Breakdown Callouts
If you need us, you jump the queue — priority engineer response.
✔ Safety Checks & Service Reminders
Never miss a service. Automatic reminders by email and text.
✔ Full Aftercare & Support
Warranty registration, documentation, advice — all handled by us.
Switch to Silver Cover after Year 1
Continue your protection from just £6.99 per month after the free first year.
What Affects the Cost?
The price of a back boiler replacement in South Wales varies depending on a few key factors. These don’t just affect the upfront price — they also influence how long the job takes and what materials are required.
1. Boiler Type & Model
Different boiler systems come with different material and labour requirements.
Typical ranges:
• Boiler conversions: £3,000–£4,200
(converting from regular/system/back boiler to combi or system – includes pipework changes and removal of tanks/cylinder)
- Back boiler replacement: £3,000–£4,500
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Combi boiler replacement: £1,800 – £3,000
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System boiler replacement: £2,200 – £3,200
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Conventional (heat-only) replacment: £2,300 – £3,200
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Electric boiler replacement: £1,800 – £5,500
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Oil boiler replacement: £3,200 – £6,500
Higher-end boilers cost more but offer better efficiency, quieter operation, and longer warranties.
2. Installation Complexity
Some installs are simple like-for-like swaps. Others require more engineering time.
Costs increase when any of the following apply:
✔ Switching from a back boiler, floor standing boiler.
✔ Upgrading or replacing the hot water cylinder
✔ Adding or upgrading pipework
✔ Installing additional safety or regulatory components
✔ Limited access (tight cupboard, attic, etc.)
Additionally:
✔️ Removing hot water cylinders or loft tanks (if converting to a combi)
✔️ Rerouting or upgrading pipework to suit the new boiler type.
3. Flue Setup (Horizontal / Vertical)
The flue is a key safety component and can affect labour time.
Typical ranges:
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Horizontal flue: £150 – £450
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Vertical flue: £350 – £850
Vertical flues require more labour and often need roof access — which increases cost.
4. Plume Kit (if required)
Required when a flue terminal is too close to windows, doors, or boundaries.
Average cost: £80 – £150
Not every home needs one — but many terrace and semi-detached homes do.
5. Gas Pipe Upgrade (15mm → 22mm)
To meet Gas Safe and boiler manufacturer requirements, most modern boilers require a 22mm gas supply.
Typical cost: £200 – £800
Blue Flame upgrade cost: Included where required (no additional labour cost)
This is a major hidden cost most companies don’t explain upfront.
6. Boiler Relocation
Moving a boiler is one of the biggest cost changers.
Typical ranges:
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Same room: £400 – £800
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Different room: £700 – £1,000
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Different floor: £800 – £1,200
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Loft/attic: £800 – £1,200
More copper, more labour, more materials → higher cost.
7. Additional Upgrades (Optional / Recommended)
Many installations require or benefit from additional components:
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Magnetic filter: £80 – £120
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Chemical flush: £20 – £60
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Smart thermostat (Nest/Hive/Tado): £40 – £80
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New radiators (per radiator): £200 – £400
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TRVs: £15 – £30 each
Blue Flame includes a magnetic filter as part of most installs.
8. Property Size & Layout
Larger or more complex homes can require:
✔ More pipework
✔ More radiators
✔ More labour time
✔ Larger boiler outputs
Typical home ranges:
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Flat / apartment: £1,800 – £3,000
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Mid-terrace: £2,200 – £3,600
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Semi-detached: £2,400 – £4,000
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Detached: £3,000 – £5,000+
9. Radiator Condition & System Health
Older or heavily-sludged heating systems can affect boiler performance and installation requirements.
Typical checks include:
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Radiator cold spots or slow heat-up
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Poor circulation caused by sludge build-up
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Old TRVs that no longer work efficiently
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Blocked pipework restricting flow
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System pressure dropping regularly
Why it matters:
A new boiler works best with a clean, free-flowing system. In some cases, a power flush or chemical clean is recommended to protect the new boiler and improve whole-home performance.
10. Boiler Controls & Thermostats
Modern controls help your system run more efficiently — and are now recommended by most manufacturers.
Common control types:
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Basic on/off digital thermostats
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Wireless programmable thermostats
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Smart controls (Hive, Nest, Tado)
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Weather-compensating controls
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Load-compensating controls (mandatory on new installs)
Installation impact:
Smart controls may require additional wiring, receivers, or setup time during installation — slightly increasing labour.
11. Smart Thermostat Upgrades (Optional)
Upgrading to a smart heating system is one of the easiest ways to improve comfort and reduce bills.
Benefits include:
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Control heating from your phone
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More accurate temperature management
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Energy-usage insights
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Eco modes & scheduling
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Long-term cost savings
Typical price range:
£120 – £250 for supply & setup, depending on brand.
Blue Flame installs Nest, Hive, Tado and other leading smart systems.
12. Chemical Flush & Water Treatment
Every new installation requires proper system protection — and this is where water treatment comes in.
Your installation includes:
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Full chemical cleanse
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Inhibitor added after installation
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Magnetic filter (included at no extra cost)
Why this matters:
Good water quality prevents corrosion, sludge build-up, and premature boiler failures. It also helps maintain efficiency and protects your manufacturer warranty.
Blue Flame Promise — No Hidden Extras
All quotes from Blue Flame include:
✔ Fixed pricing
✔ Gas Safe installation
✔ All required materials
✔ Full documentation
✔ Free Silver Cover (12 months)
✔ Blue Flame In-House Warranty
Everything you need. No unexpected add-ons.
Typical Price Ranges in South Wales
Body content (use exactly as below):
Every home is different — but these ranges give you a realistic idea of what homeowners typically pay for a new gas boiler installation in South Wales.
Boiler Conversion (Any Type → Combi/System)
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Typical range: £3,000–£4,200
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Includes removal of old tanks/cylinder (if required)
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Extra cost for relocating the boiler or upgrading gas pipework
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Most conversions take 2 days
Back Boiler Replacement (Baxi Bermuda & similar)
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Typical range: £3,000–£4,500
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Includes removal, chimney/flue sealing, and installation of a new combi or system boiler
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Final price depends on new boiler location and pipework requirements
Combi Boilers (Most Popular)
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Small flat/home: £1,800 – £2,300
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2–3 bedroom home: £2,200 – £3,000
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Larger home: £3,000+
System Boilers
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Typical range: £2,300 – £3,200
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Ideal for properties with a hot-water cylinder
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Often chosen for larger home with multiple Bathrooms
Conventional Boilers (Regular / Heat-Only)
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Typical range: £2,200 – £3,200
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Includes removal of tanks & pipework (if upgrading)
Electric Boilers
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Typical range: £1,800 – £5,500
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Suitable for smaller homes, flats, or areas without gas
Oil Boilers
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Typical range: £3,200 – £6,500
Quick note:
Blue Flame quotes always include all materials, Gas Safe installation, documentation, and 12 months of Silver Cover.
Estimated Costs by Property Type
Every home layout is different — but these ranges show what homeowners in South Wales typically pay for boiler conversion based on property size.
| Property Type | Typical Cost (Inc Installation) |
|---|---|
| Small Flat / 1–2 Bedroom Home (conversion) | £2,600 – £3,000 |
| Medium 2–3 Bedroom Home | £3,000 – £4,000 |
| Large 3–4 Bedroom Home | £3,200 – £4,200 |
| Large Detached / High-Demand Homes | £3,400 – £4,500+ |
Grants & ECO4 Funding (Are You Eligible?)
If you meet certain criteria, you may qualify for a new A-rated boiler fully funded through the Government’s ECO4 scheme. This programme helps households improve energy efficiency and reduce heating costs.
You may qualify if your home has:
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A low EPC rating (E, F or G)
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An old, inefficient boiler
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Poor insulation or high heating bills
And you receive one of the following:
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Universal Credit
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Child Benefit (income-based criteria)
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Income Support
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Jobseeker’s Allowance
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Working Tax Credit
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Housing Benefit
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Pension Credit
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Income-related ESA
If you’re not sure, we can check eligibility for you in less than 60 seconds.
Call us or click Contact Us — we’ll run a free ECO4 eligibility check for your home.
How Much Could You Save With a New A-Rated Boiler?
A new, energy-efficient boiler can reduce your heating bills immediately — especially if your current boiler is older, oversized, or losing heat through poor efficiency.
Below is a simple guide showing typical savings for homes in South Wales after upgrading to a new A-rated boiler.
Annual Savings (Based on Energy Savings Trust Data)
| Current Boiler Type | Estimated Annual Saving |
|---|---|
| Old G-rated Boiler | £245 – £840 |
| Old F-rated Boiler | £180 – £550 |
| Old E-rated Boiler | £100 – £300 |
| Old D-rated Boiler | £60 – £160 |
Quick Summary
Boiler conversions involve upgrading an existing system to a new boiler type, such as removing tanks and switching to a combi, or relocating the boiler to a better position.
You can also compare detailed installation costs by boiler type and fuel source in our cost guides →
Here’s a quick breakdown:
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Combi boilers are ideal for small to large homes with upto 2 bathrooms.
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System boilers suit larger homes with higher hot-water demand and properties already fitted with a hot water cylinder.
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Regular (heat-only) boilers are best when upgrading older systems with existing tanks. Ideal for all homes.
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Electric boilers work for homes without gas or with low heating demand.
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Oil boilers remain common in rural areas without mains gas.
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Installation costs vary based on boiler type, complexity, and home layout.
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A new A-rated boiler can reduce heating bills by £60–£840 per year.
All Blue Flame installations include:
✔ Fixed pricing
✔ Gas Safe installation
✔ All required materials
✔ Full documentation
✔ 12 months of Silver Cover (FREE)
Frequently Asked Questions
What is the Blue Flame In-House Warranty™?
The Blue Flame Warranty™ is your local, engineer-backed boiler warranty — designed to give you better protection than national companies.
It includes:
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12 months of free aftercare
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Priority breakdown response
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No call centres — you speak directly with our South Wales team
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All callouts handled by Blue Flame engineers
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Manufacturer parts supplied where needed
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Warranty stays valid with annual Blue Flame servicing
This is one of the strongest local warranties available and a major reason homeowners choose Blue Flame over national brands.
What types of boiler conversions are most common?
Common upgrades include:
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Regular (heat-only) → Combi
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System → Combi
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Back boiler → Combi
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Regular → System
Blue Flame will recommend the best option during your survey.
How much does a boiler conversion cost?
Most replacements cost £3,000–£4,200, depending on the new boiler type, installation location, and any chimney/fireplace work required.
Will converting to a combi boiler save space?
Yes — combis free up:
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airing cupboards
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loft space
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hot water tanks
Many homeowners choose conversions specifically to reclaim space for storage.
Tip – We can install a small radiator in the Airing Cupboard. You can continue to dry clothes and towel, if desirable.
Do I need to remove my hot water cylinder and loft tanks?
Only if you’re converting to a combi boiler.
If converting to a system boiler, you keep (or upgrade) the cylinder.
Blue Flame will confirm the best option during your quote.
Can I convert to a combi boiler even if my current boiler is in a different room?
Yes. Most boiler conversions involve fitting the new combi or system boiler in a more suitable location such as the kitchen, utility room, or airing cupboard.
Blue Flame will check flue options, pipework routing, and water pressure to confirm the best location.
What’s included in a Blue Flame boiler installation?
You receive a fully inclusive service:
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Fixed-price quote
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Gas Safe installation
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Magnetic filter (where required)
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System cleaning
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Wireless controls setup
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Full commissioning
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Digital documentation
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Warranty registration
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Free 12 months of Silver Cover aftercare
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Blue Flame Warranty™ — we handle all callouts in year one
No hidden extras. No upsells. No surprises.
Frequently Asked Questions
What are the benefits of having an in-house warranty instead of relying only on manufacturers?
An in-house warranty gives homeowners faster, clearer and more reliable support. With most manufacturers, you’re routed through call centres, scheduled into national queues, and often left waiting days for an engineer.
With the Blue Flame Warranty™, all aftercare is handled directly by our local engineers, meaning quicker response times, one point of contact, and much less hassle. We diagnose faults, attend breakdowns, and only involve the manufacturer when a replacement part is required.
This gives you the reliability of a manufacturer warranty, but with the speed and service of a trusted local company.
How long does a boiler conversion take?
A boiler conversion usually takes 2days. Depending on variables
- New gas pipework
- Re-configure pipework
- Flue through roof
- Wiring alteration
Blue Flame will discuss the finer details as part of your home survey.
Will my gas pipe need upgrading to 22mm?
Modern boilers often require a 22mm gas supply to meet manufacturer and Gas Safe regulations. If your existing pipe is undersized, Blue Flame will upgrade it during installation.
This is common in older South Wales properties, particularly terraces and semis. Cost depends on routing and access but will be clearly included in your fixed-price quote.
Do boiler quotes vary between companies?
Yes. Some national brands add extra charges for filters, flue components, or safety upgrades. Blue Flame pricing is fully transparent and includes all required materials, labour, and safety components.
Our quotes also include 12 months of free aftercare, so homeowners get far more value compared to national companies with higher overheads.
Plus the In-House The Blue Flame Warranty™
How does the installation process work with Blue Flame?
Our process is simple:
- Free quote or survey
- Fixed-price agreement
- Gas Safe installation
- System cleaning & testing
- Commissioning & documentation
- Warranty registration
- Your Blue Flame Warranty™ begins automatically
- You receive aftercare and reminders throughout the year
This system ensures full transparency and a stress-free installation.
Does the Blue Flame Warranty™ prevent blame-shifting between manufacturers and installers?
Yes — and this is one of its biggest advantages. With national installers, it’s common for manufacturers to blame the installer, and installers to blame the manufacturer, leaving homeowners stuck in the middle.
This removes that problem completely. We handle everything internally: diagnostics, callouts, communication, and arranging parts. If it’s an installation issue, we fix it. If it’s a boiler issue, we fix it.
There’s no finger-pointing, no confusion, and no delays — just a clear, accountable team that takes full responsibility for your boiler’s performance.