Installing a new boiler means restoring comfort and compliance, but how long does it take to fit a new boiler and how long will you be without heating and hot water? For most UK installations, a simple like-for-like swap takes approximately 1.5 days yet more involved installations can stretch to five days or more.
At Paine Manwaring, our Gas Safe registered engineers support both homes and businesses across Sussex and Hampshire. This guide outlines typical boiler installation times, the factors that can impact timeframes, and what to expect from the service. If you’re planning a replacement and value reliability and safety, connect with us today to schedule a site visit with a trusted Gas Safe team.
Why Boiler Installation Time Matters
When you need a new boiler, timing is about more than convenience. The impact varies depending on your role:
- Homeowners – being without heating or hot water for even a day can cause major disruption to daily life
- Landlords – have a legal duty to provide tenants with heating and hot water, so delays can quickly lead to complaints or breaches of tenancy agreements
- Facilities managers – face pressures from prolonged downtime, which can affect staff comfort, building compliance and, in some cases, business operations
New boiler installation time also directly affects cost. Longer jobs mean higher labour charges and, if temporary heating is needed, additional expense. Safety is another critical factor. According to the Gas Safe Register, around 1.1 million illegal gas jobs are carried out in the UK each year, with three out of five found to be unsafe. That highlights why using a qualified Gas Safe engineer is essential, even when speed is a priority.
Understanding how long an installation will take allows you to plan around disruption, set clear expectations and keep both costs and compliance under control.
Factors That Affect Boiler Installation Time
The length of time it takes to fit a new boiler depends on several practical factors. Some are straightforward, while others can add days to the job.
Type of boiler (combi, system, regular)
Combi boilers are usually the fastest to install because they provide heating and hot water directly from one unit, without the need for separate tanks or cylinders. In many cases, a like-for-like combi swap can be completed in 1.5 days. System and regular (also known as conventional) boilers are more involved, as they rely on cylinders and tanks.
Replacing vs. upgrading to a different boiler
Replacing an old boiler with the same type in the same position is always quicker than an upgrade. Switching, for example, from a regular boiler to a combi requires adjusting pipework and removing tanks.
“When we upgrade a property from a regular boiler to a combi, it’s not just a swap – it’s often a complete redesign of the system layout. That extra work adds at least a day and a half to the schedule, but it ensures the system is safe, compliant and built to last.”
– Adam Doick, Director at Paine Manwaring.
Location of the boiler (same place vs. moving position)
If the new boiler is fitted where the old one sat, installation is simpler. Moving it to a new location is more time-consuming, as engineers must reroute gas, water and condensate pipes, and drill a new flue opening through an external wall. For larger buildings, this may also mean coordinating with building control. On average, relocating a boiler can add two full days to the job.
Age and condition of existing pipework and system
Older systems often bring hidden complications. Corroded pipes, outdated fittings or undersized gas supply lines may need replacing before a new boiler can be commissioned. If repairs or upgrades are needed, this can extend the project significantly.
Additional upgrades (flue, radiators, thermostats, controls)
Adding a smart thermostat or upgrading radiators all increase new boiler installation time. While these steps extend the job, they improve efficiency and compliance with Building Regulations Part L (conservation of fuel and power). Installing smart heating controls is now recommended as standard in UK homes and can add extra time to a typical installation.
Complexity of the job & property size
The size and complexity of the property make a big difference. A small home with six radiators can often be drained and refilled quickly, while a commercial property with multiple zones, pumps and lots of radiators requires more time for testing and balancing.
“For larger buildings, commissioning the system properly is just as important as fitting the boiler itself. Rushing that stage risks uneven heating and long-term faults.”
– Adam Doick, Director at Paine Manwaring.
How Long Does It Take to Fit Different Types of Boilers?
New boiler installation time varies depending on the system and property, but there are clear patterns our engineers regularly encounter in homes, rental properties and larger buildings. The outline below reflects the typical timescales seen with different types of boiler, although the exact duration will always depend on the individual installation.
Combi boiler installation time
- Timeframe: usually completed in 1.5 days for a like-for-like replacement in the same location
- What’s involved: fitting the unit and connecting pipework.
System boiler installation time
- Timeframe: typically two to three days
- What’s involved: installation of the boiler and connection to a hot water cylinder
Regular (conventional) boiler installation time
- Timeframe: generally two to three days
- What’s involved: installation of the boiler, hot water cylinder and cold-water storage tanks
Replacement boiler vs. new installation
- Like-for-like replacement (same type, same location): usually completed in 1.5 days
- Replacement with upgrades (different boiler type or pipework changes): typically three days
- Completely new installation (relocation of the system): generally five days or more, as it requires new pipe runs and flue work.
Typical Timeframes for Boiler Installations
The overall duration depends not just on the type of boiler but also on how straightforward the job is. These are the scenarios our engineers most often encounter:
Simple like-for-like replacement – usually 1 day
- Timeframe: around 1.5 working days
- Process: remove old boiler, fit new unit in the same position, connect to existing pipework
- Considerations: quickest option as it involves minimal changes – often chosen when upgrading to a newer model of the same type.
Moving the boiler – 3+ days
- Timeframe: typically 3+ days
- Process: rerouting gas, water and condensate pipes, drilling a new flue exit, capping old pipework
Considerations: access restrictions, structural work and building control approvals can extend this
Full system upgrade – 5+ days
- Timeframe: usually 5 days or more
- Process: replacing boiler, radiators, pipework and removing hot water cylinders and tanks
Considerations: larger properties and commercial sites require more commissioning time to balance the system correctly
Emergency boiler installations
- Timeframe: depends on availability of parts and access, but engineers will usually prioritise restoring heating and hot water within 24 hours where possible
- Process: temporary solutions may be used while the new boiler is sourced and fitted
- Considerations: still requires full Gas Safe testing and Building Regulations Compliance certification, so safety is never compromised even under time pressure.
At Paine Manwaring, our engineers provide an emergency call-out service across Sussex and Hampshire to make sure urgent heating and hot water issues are dealt with quickly and safely. If you require this service, please contact us on 01903 237522
What to Expect When Having a New Boiler Fitted
Knowing what will happen on installation day helps you plan ahead and avoid surprises.
Will it be messy?
Boiler installations involve removing old equipment, cutting into pipework and sometimes drilling new flue exits. This inevitably creates some dust and debris. Engineers will use dust sheets and tidy as they go, but it’s sensible to clear the area around the boiler beforehand and protect nearby furniture or flooring.
Do engineers need access to all radiators?
Yes. In most cases, the system will need to be drained and refilled, which requires access to every radiator so they can be bled properly. If you’re a homeowner, landlord or facilities manager, it’s important to make sure all areas of the property are accessible before the work starts.
Disruption to heating and hot water
Heating and hot water will be unavailable during the new boiler installation. For a straightforward replacement this usually means a single day without services, but more complex upgrades will take longer. In emergencies, engineers may be able to provide temporary solutions while the installation is completed.
Safety checks and testing after installation
Every installation ends with a full series of safety and performance checks. These include testing the gas supply for leaks, checking flue performance, verifying water pressure and balancing the system. Once complete, the engineer will commission the boiler and issue the necessary Building Regulations Compliance Certification to confirm that it has been installed safely and in line with UK regulations.
Paine Manwaring’s Expert Tips on Boiler Installation
A new boiler installation is a major investment, and the installation process runs more smoothly when you prepare in advance. Based on our experience supporting homeowners, landlords and facilities managers across Sussex and Hampshire, here are some practical steps to keep in mind.
- Check Gas Safe registration – In the UK it’s a legal requirement for anyone installing a gas boiler to be Gas Safe registered. Always ask to see your engineer’s credentials before work begins.
- Plan for access – Make sure the area around the boiler is clear and that all radiators are easy to reach. This saves time on the day and avoids delays.
- Discuss upgrades in advance – If you’re considering smart controls, new radiators or changes to the flue position, agree these before work starts so everything can be factored into the schedule.
- Ask for a clear timescale and breakdown – Understanding what’s included helps you manage costs and set expectations, especially with tenants or building users.
- Request commissioning paperwork – After installation, you should receive all necessary certification and confirmation that all safety checks and system balancing have been carried out.
“The installation itself is only one part of the job. Good preparation makes a big difference. When access is planned and decisions on controls or upgrades are made early, the whole process is more efficient and disruption is kept to a minimum.”
– Adam Doick, Director at Paine Manwaring.
Planning Your Boiler Installation
The time needed to fit a new boiler will always depend on the type of system, the condition of existing pipework and whether upgrades are required. A simple replacement can often be completed in a single day, while moving the boiler or carrying out a full system upgrade will take longer. By understanding the likely timescales and preparing the property in advance, you can minimise disruption and keep the process as straightforward as possible.
Paine Manwaring offers domestic and commercial heating services across Sussex and Hampshire. We provide routine servicing, emergency repairs and full system upgrades.
To arrange a visit or speak to an expert, contact our team.
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Frequently Asked Questions About New Boiler Installation Time
How long does it take to remove and install a new boiler?
For a straightforward like-for-like replacement, the process is usually completed within a day and a half. This includes removing the old unit, fitting the new boiler, connecting it to the existing pipework and carrying out the necessary safety checks. If the job involves upgrades, moving the boiler or replacing additional components such as radiators or cylinders, allow at least another three days.
What to expect when having a new boiler fitted?
On the day of installation, engineers will remove the old unit, fit the new boiler and make any adjustments needed to the pipework, flue or controls. Heating and hot water will be unavailable until the system is recommissioned. Some noise and dust are unavoidable, though protective sheets are usually used to minimise mess. At the end of the process, the engineer will carry out full safety checks and provide the necessary certification.
Is fitting a new boiler a big job?
The scale of the job depends on what’s required. A simple replacement in the same location is relatively straightforward and can be finished in a day and a half. More complex projects, such as changing to a different boiler type, moving the unit or upgrading the whole system, are bigger jobs that take several days and involve more disruption. Regardless of complexity, every installation must be completed by a Gas Safe registered engineer to ensure safety and compliance.
Paine Manwaring is an established, professional and highly experienced supplier of plumbing, heating and electrical services to domestic and commercial customers throughout Sussex, Surrey and Hampshire.
For more information about our heating, plumbing and electrical services which we provide for both homes and businesses, get in touch with a member of our expert and friendly team today on 01903 237522 or enquiries@painemanwaring.co.uk (Worthing) or 01243 784711 or info@painemanwaring.co.uk (Chichester).
