A new boiler installation in Cheshunt starts with a survey of your home and heating system, moves on to choosing the right type and size of boiler, and is then usually fitted in one to two days for a straight swap, or longer if the boiler is moving or the system type is changing. Done properly, it ends with a cleaned and protected system, a commissioned boiler, the manufacturer’s guarantee registered and a Building Regulations compliance certificate in your name.

Is it time for a new boiler?

Not every broken boiler needs replacing. A boiler that is otherwise reliable and needs one reasonably priced part is usually worth repairing. It becomes time to think about replacement when breakdowns are becoming regular, parts are getting hard to find, the repair quote is a large share of the cost of a new boiler, or the boiler is well into the later years of its life. Our guide on whether to repair or replace a boiler sets out how we make that call honestly.

If you have decided to replace it, here is what a proper boiler installation involves, from first visit to handover.

Step 1: the survey

A good installer does not price a boiler from a photo of the old one. A survey should cover:

• Hot water demand. How many bathrooms, how many people, whether two showers run at once, and whether you have a bath that needs filling quickly.
• Mains water pressure and flow. A combi can only deliver hot water as fast as the mains supply allows, so this is measured, not assumed.
• Heat loss and boiler output. The boiler should be sized to the home, not simply matched to the old one, which was often oversized.
• Flue route. Where the flue can exit safely, keeping the distances from windows, doors, boundaries and other openings that the manufacturer’s instructions require.
• Gas supply. Modern boilers often need a larger gas pipe than the old one. The engineer checks the pipe size and the pressure at the boiler.
• Condensate. Every condensing boiler produces acidic water that has to drain away, ideally internally. An external run needs to be designed so it will not freeze in winter.
• Existing system condition. Signs of sludge, cold radiators, leaks or an old open-vented system that may need changing.
• Controls. What you have now and what the new boiler needs to meet the regulations.

Step 2: choosing the right boiler

Boiler type	How it works	Usually suits	Things to consider
Combi	Heats water on demand from the mains, no cylinder or tanks	Flats and most homes with one or two bathrooms	Hot water flow depends on mains pressure, one outlet at full flow is best
System	Heats a hot water cylinder, sealed system, no loft tanks	Homes with two or more bathrooms used at the same time	Needs space for a cylinder, often an unvented one
Regular (heat only)	Works with a cylinder and loft tanks	Homes with existing open-vented systems, or where mains pressure is low	Uses more space, can often be kept to avoid major changes

Water across most of Hertfordshire is hard, which builds limescale in the parts of a boiler that heat domestic water. That is worth factoring in: a scale reducer is often fitted on combi installations in hard water areas, and some manufacturers require one for their guarantee.

For brand and model advice, our guide to the best combi boilers compares the main options. We are an Ideal Max accredited installer and a Vaillant myREWARDS installer, which means selected Ideal boilers we fit can come with manufacturer guarantees of up to 12 years, and selected Vaillant boilers up to 10 years.

What the regulations require

Every new gas boiler in England has to meet Part L of the Building Regulations for energy efficiency. In practice that means:

• A condensing boiler with a seasonal efficiency (ErP) of at least 92%.
• Time and temperature controls, meaning a programmer or timer and a room thermostat.
• For a combi boiler, at least one extra energy-saving measure, such as weather compensation, load compensation, a smart thermostat with automation and optimisation, or flue gas heat recovery.
• Individual room temperature control, usually TRVs on the radiators, where it is practical.
• The system cleaned and treated before the new boiler goes on, and the boiler commissioned to the manufacturer’s instructions.

The installation must be carried out by a Gas Safe registered engineer, who notifies it through Gas Safe Register. Gas Safe Register then sends you a Building Regulations compliance certificate. Keep it, because you will need it when you sell the house.

Step 3: installation day

For a like-for-like replacement, a typical installation goes like this:

1. Protect the home. Dust sheets down, and the work area cleared.
2. Drain down and remove the old boiler. The old boiler is disconnected, removed and taken away.
3. Clean the system. The heating system is flushed so sludge and debris do not damage the new boiler. On a heavily sludged system, this may be a full power flush.
4. Fit the new boiler. New wall bracket, pipework adapted, new flue, condensate pipe run, and gas supply upgraded if needed.
5. Fit the filter and controls. A magnetic system filter goes on the return pipe, and the new thermostat or smart controls are wired in.
6. Fill, test and treat. The system is filled, bled, pressurised and dosed with inhibitor, and every joint is checked.
7. Commission. The engineer checks the gas rate and pressure, carries out flue gas analysis and fills in the Benchmark commissioning checklist.
8. Handover. You are shown how to use the boiler and controls, how to check and top up the pressure, and what to do if a fault code appears.

Moving the boiler to a new position, converting from a regular to a combi system, or taking out a loft tank and cylinder all add time, usually a day or more.

Guarantees and paperwork

After a new boiler installation you should have:

• The Benchmark commissioning checklist, completed and signed.
• A Building Regulations compliance certificate, arranged through Gas Safe Register.
• The manufacturer’s guarantee, registered with the manufacturer. Most require registration within a set time and a service every year to keep it valid.
• The installer’s workmanship guarantee. Ours is 12 months on labour, alongside the manufacturer’s guarantee on the boiler.

Every new boiler package from Vantage includes a magnetic system filter, the first year’s service and removal of the old boiler.

How we price it

Installations are quoted as a fixed price after a free survey, so the price you agree is the price you pay. You can get your price online in a couple of minutes with our boiler quote tool, and our general rates for other work are on our prices page.

Frequently asked questions

How long does a new boiler installation take?

A like-for-like swap in the same position usually takes one to two days. Moving the boiler, or changing from a regular or system boiler to a combi, takes longer because of the extra pipework and the removal of tanks or a cylinder. Your installer should tell you the expected time at the survey.

Do I need to be at home during the installation?

Someone needs to be there at the start to let the engineers in and agree the plan, and at the end for the handover. In between, you do not need to stay in, but you will be without heating and hot water for most of the day.

Can I have my boiler moved to a different room?

Usually, yes, as long as there is a safe flue route, a way to drain the condensate and access for the gas and water pipes. Moving a boiler adds time and cost, so the survey should look at whether the benefit is worth it.

Do I need a power flush with a new boiler?

The system must be cleaned before a new boiler is fitted, and most manufacturers require it for their guarantee. Whether that means a full power flush or a chemical clean depends on how dirty the system is, which the engineer checks on the survey.

Which boiler brands do you install?

We are an Ideal Max accredited installer and a Vaillant myREWARDS installer, so selected Ideal boilers can come with manufacturer guarantees of up to 12 years, and selected Vaillant boilers up to 10 years. We repair and service all the major brands.

New boilers in Cheshunt and across Hertfordshire

We install new boilers in Cheshunt, Hoddesdon and the rest of the Broxbourne area from our base in Stevenage, and across Hertfordshire, Bedfordshire and Cambridgeshire. Find out more about our boiler installation service or call 01462 506374 to arrange a free survey.