Step-by-Step: What Happens During a Boiler Installation

Booking a new boiler can feel daunting if you are not sure what to expect. Understanding each step of the boiler installation process helps you prepare your home, your schedule and your budget with confidence.

From first enquiry to fixed quotation

For most homes in Milford Haven and Johnston, the process starts with an initial chat by phone or email. The engineer will ask a few questions about your current boiler, any problems you are having and the size of your property.

In many cases, a home survey is then arranged. This visit usually takes around 30 to 60 minutes. The engineer checks your existing boiler, pipework, gas meter and flue position, and asks about your hot water usage and any future plans, such as extensions or extra bathrooms.

After the survey, you should receive a written quotation. This will set out the boiler model, what is included in the price, any optional extras and an estimated timescale for the work. For a straight swap, most installations take one full day, while more complex jobs can take two to three days.

Preparing your home for installation day

A little preparation before your engineer arrives can save time and reduce disruption. You do not need to move heavy furniture, but clear access to key areas makes a real difference.

• Ensure the area around the existing boiler is free from clutter
• Make sure the engineer can reach the gas meter and consumer unit
• Clear access to radiators if any are being removed or replaced
• Agree parking arrangements and let the engineer know about restrictions

If you have pets or young children, it helps to plan where they will be during the noisier parts of the work. Your heating and hot water will usually be off for most of the installation, so it is sensible to plan showers, cooking and working from home around this.

What happens when the engineer arrives

On the morning of the installation, the engineer will introduce themselves, run through the plan for the day and confirm where the new boiler will go. They should also explain any expected downtime for heating and hot water.

Before any work starts, protective coverings are normally laid on floors and surfaces along the work route. The engineer will then isolate the boiler, gas and electrics where needed, and drain the central heating system so the old boiler and pipework can be safely removed.

Removing the old boiler and preparing the system

The first major task is to disconnect and remove the old boiler. This can take one to three hours depending on access and how it was originally installed. Flue parts, old brackets and redundant controls are also removed at this stage.

The engineer will then assess the existing pipework and decide what needs to be altered or upgraded to suit the new boiler. For older systems, they may recommend a system cleanse to remove sludge and debris, often done with chemicals or a powerflush if agreed in the quote.

Fitting the new boiler and controls

Once the wall is prepared, the new boiler is hung and connected to gas, water and heating pipework. The flue is fitted through an external wall or roof and carefully sealed to prevent any leaks.

The engineer then connects the condensate pipe to a suitable drain, following current regulations. Modern boilers usually need new controls, such as a programmable thermostat or smart controls. These are wired or linked to the boiler and tested for communication.

For most standard replacements, this stage usually takes half a day. More complex re-pipes or relocating a boiler to a new room will add extra time.

Filling, testing and commissioning

With everything connected, the system is refilled with water and bled of air at the radiators. The engineer will add inhibitor chemicals to protect against future corrosion unless your quote states otherwise.

They then carry out a series of checks, which typically include:

• Gas tightness test to ensure there are no gas leaks
• Flue integrity and combustion checks with a flue gas analyser
• Verification that safety devices and cut-outs operate correctly
• Checking boiler pressures, flow rates and temperature settings

This commissioning process is essential for safety, efficiency and validating the boiler warranty. It usually takes one to two hours, depending on the system and any adjustments required.

Clean-up, paperwork and handover

Once the engineer is satisfied that the boiler is working correctly, they will tidy up, remove rubbish and leave the area clean. Any old boiler parts are usually taken away for proper disposal or recycling.

The handover is your chance to get familiar with the new system. The engineer should show you how to:

Use the controls, adjust temperatures, set programmes and reset the boiler if needed. They should also explain the basic pressure checks you can do yourself and when to call for help.

You should receive a benchmark or commissioning sheet, warranty information and, in the case of gas boilers, notification that your installation will be registered with Gas Safe and Building Control. Registration certificates typically arrive by post or email within a couple of weeks.

Aftercare, follow-up and typical timescales

For most homes, a straightforward boiler installation in Milford Haven or boiler installation in Johnston will be completed in one day, with the engineer leaving your heating and hot water back on before they go. More involved work may need a second day, which your installer should flag when planning the job.

Your engineer may schedule a follow-up call or visit if anything needs fine tuning, such as balancing radiators or adjusting settings. Annual servicing is essential to keep your warranty valid and your system running efficiently, so it is wise to book your first service date as soon as the boiler is installed.

Ready to plan your boiler installation?

Knowing what happens at each stage makes arranging a new boiler far less stressful and helps the whole job run smoothly. From the first survey to the final safety checks, a clear process gives you confidence that your home is in good hands.

If you’re considering a boiler installation in Milford Haven or Johnston and want a reliable, professional service, we’re here to help every step of the way. Call us today on 07939012055 or visit our contact page to discuss your requirements.