Planning a boiler installation requires understanding the timeframes involved for different system types. As experienced heating engineers in Henley, we’re often asked how long the process takes from start to finish. Whether you’re replacing an existing system or installing a completely new one, this guide will help you plan effectively for your boiler installation in 2025.

Average Installation Times by Boiler Type

Different boiler systems require varying installation timeframes:

Combi Boiler Replacement (Like-for-Like)

Timeline: 4-8 hours (1 day)

When replacing an existing combi boiler with a new combi model in the same location, the process is relatively straightforward:

• System drainage: 30-45 minutes
• Old boiler removal: 30-45 minutes
• New boiler mounting and connection: 2-3 hours
• System refilling and testing: 1-2 hours
• Controls setup and customer demonstration: 30 minutes

As professional boiler installers, we can typically complete a straightforward combi swap in a single day with minimal disruption to your home.

Combi Boiler Relocation

Timeline: 8-12 hours (1-2 days)

Moving a combi boiler to a new location adds complexity:

• System drainage: 30-45 minutes
• Old boiler removal: 30-45 minutes
• New pipework installation: 2-4 hours
• Boiler mounting and connection: 2-3 hours
• System refilling and testing: 1-2 hours
• Making good (plasterwork, etc.): May require separate visit

Relocating a boiler often requires additional pipework and potentially structural work to accommodate flues and pipework routes, extending the timeline into a second day.

System to Combi Conversion

Timeline: 1-2 days

Converting from a system or regular boiler to a combi involves significant changes:

• Removal of hot water cylinder and tanks: 2-3 hours
• Old boiler removal: 30-45 minutes
• Pipework reconfiguration: 4-6 hours
• New combi installation: 2-3 hours
• System flushing and testing: 2-3 hours
• Controls setup: 30-45 minutes

This conversion fundamentally changes your heating system architecture, requiring more extensive work but offering the benefit of freeing up space previously occupied by water tanks.

LPG Boiler Installation

Timeline: 1-3 days

LPG boiler installations involve additional components:

• Boiler installation: 4-8 hours (similar to combi timeline)
• LPG tank installation: 3-6 hours
• Groundworks for tank placement: May add an extra day
• Supply line installation: 2-4 hours
• Gas safety testing: 1-2 hours

The overall timeline depends significantly on whether you’re switching from another fuel type or replacing an existing LPG system. New LPG installations typically require coordination with your gas supplier for tank placement.

Oil Boiler Installation

Timeline: 2-3 days

Oil boilers involve more complex systems:

• Boiler installation: 6-8 hours
• Oil tank installation (if needed): 4-6 hours
• Oil supply line and fire valve: 2-3 hours
• System commissioning: 2-3 hours
• OFTEC certification: 1 hour

Oil systems require specific safety features and regulatory compliance checks that extend the installation period. If groundworks are needed for a new oil tank base, this can add an additional day.

Heat Pump Installation

Timeline: 2-5 days

Heat pump systems represent the most complex installations:

• Heat pump unit installation: 6-8 hours
• External groundworks/mounting: 4-6 hours
• Internal system changes (larger radiators/underfloor): 1-3 days
• Buffer tank installation (if required): 3-4 hours
• Controls and commissioning: 4-6 hours

The wide timeframe reflects the variability in heat pump installations, with some requiring significant modifications to existing heating distribution systems to work efficiently.

Factors That Can Extend Installation Timeframes

Several variables can impact your installation schedule:

Property-Specific Factors

• System accessibility: Difficult-to-reach boilers or pipework
• Property age: Older buildings may have non-standard pipework
• Structural issues: Need for additional supports or modifications
• Flue routing complexities: Multi-story buildings or challenging exit points

System Requirements

• Power flushing requirements: Add 3-6 hours if deep cleaning is needed
• Water treatment: Additional time for scale reduction in hard water areas
• Smart control integration: More sophisticated controls require additional setup
• Radiator replacements/upgrades: Can add several hours per radiator

External Factors

• Weather conditions: Particularly for external components like flues or heat pumps
• Permit or inspection requirements: Local building regulations may necessitate inspections
• Material availability: Supply chain delays can affect scheduling

As heating engineers, we always conduct a thorough pre-installation survey to identify any potential complications that might extend the timeline.

Preparation Steps to Ensure Faster Installation

You can help minimise disruption and ensure a smoother installation by:

1. Clearing access: Ensure clear pathways to your boiler location and airing cupboard
2. Removing items: Clear storage from around the existing boiler and system components
3. Protecting belongings: Cover furniture in work areas to prevent dust damage
4. Arranging parking: Ensure engineers have convenient access to bring in equipment
5. Making decisions early: Finalise control options and preferences before installation day

System Drainage and Removal Timeframes

A crucial early stage in any replacement is removing the old system:

• Combi boiler drainage: 30-45 minutes
• System boiler with cylinder: 60-90 minutes
• Conventional system with tanks: 90-120 minutes
• Old boiler disconnection and removal: 30-60 minutes
• Hot water cylinder removal: 60-90 minutes
• Water tank removal: 60-120 minutes (depending on access)

New System Fitting and Connection Process

The installation phase includes several key stages:

1. Mounting the boiler: 30-60 minutes
2. Connecting pipework:
   • Straightforward like-for-like: 1-2 hours
   • New pipe routes required: 3-6 hours
3. Flue installation: 1-2 hours (longer for complex routing)
4. Control wiring and setup: 1-2 hours
5. System filling and venting: 30-60 minutes
6. Initial firing and adjustments: 30-60 minutes

Testing and Certification Requirements

The final phase involves comprehensive testing:

• Gas safety testing: 30-45 minutes
• System pressure testing: 20-30 minutes
• Balanced flue analysis: 15-30 minutes
• Controls programming and testing: 15-30 minutes
• Customer demonstration: 15-30 minutes
• Documentation and certification: 15-30 minutes

Real-World Case Studies with Actual Timeframes

Case Study 1: Worcester Bosch Combi Swap in Henley

• Semi-detached house
• Straightforward replacement in same location
• Total time: 5 hours
• Customer without heating/hot water: 4 hours

Case Study 2: System to Combi Conversion in Henley

• Terraced house with loft tanks
• Full conversion including cylinder removal
• Total time: 1.5 days
• Key challenge: Limited access in narrow airing cupboard

Case Study 3: Oil to LPG Conversion in Rural Henley

• Detached country property
• Complete fuel system change
• Total time: 3 days (including tank installation)
• Coordinated with LPG supplier for seamless transition

Conclusion

When planning your boiler installation, realistic timeframes help manage expectations and minimise disruption. Most straightforward replacements can be completed in a single day, while more complex system changes typically require 2-3 days. Whatever your specific requirements, our experienced team of boiler installers in Henley will provide clear timelines during the quotation process.

At TS Gas, we pride ourselves on efficient, high-quality installations that respect your time and property. Our detailed pre-installation surveys identify potential challenges in advance, allowing us to develop solutions that keep your project on schedule.

For a personalised timeline and free quotation for your boiler installation project, contact our friendly team today.

 

FAQs About Boiler Installation Timelines

Will I be without heating during the entire installation? For most installations, you’ll be without heating only during the actual system changeover—typically 4-8 hours for a standard replacement.

Do you complete all installations in the timeframe quoted? We complete over 95% of installations within the quoted timeframe. When unexpected challenges arise, we communicate promptly and work efficiently to minimise any delays.

Can installation be spread over multiple days to reduce disruption? Yes, for more complex installations, we can schedule work to ensure you have heating and hot water overnight wherever possible.