The Complete Guide to Replacing Your Boiler

A new boiler is one of the most significant home improvements you can make. A modern, efficient boiler can cut your heating bills, improve reliability, and give you much better control over your home's temperature. But with so many options available, it can be hard to know where to start.

This guide covers everything you need to know about replacing your boiler — from deciding whether you actually need a new one, to choosing the right type, to what happens on installation day.

Before spending money on a replacement, it is worth considering whether a repair might be the better option. As a rough guide:

• Boiler under 10 years old: Repair is usually the better choice, especially if the boiler has been well maintained
• Boiler 10–15 years old: Depends on the fault and the cost of repair — get a quote for both
• Boiler over 15 years old: Replacement is usually more cost-effective, and a new boiler will be significantly more efficient

Other signs that replacement makes sense include frequent breakdowns, rising energy bills despite normal usage, difficulty getting spare parts, and an F-rated efficiency rating.

Combi (combination) boilers are the most popular choice in UK homes. They heat water on demand — there is no separate hot water cylinder or cold water tank in the loft. This makes them compact, efficient, and ideal for smaller to medium-sized homes.

The main limitation is that they can struggle to supply hot water to multiple outlets simultaneously. If you have a large family or multiple bathrooms in regular use at the same time, a system or regular boiler may be more suitable.

System boilers work with a hot water cylinder (usually in an airing cupboard) but do not require a cold water tank in the loft. They can supply hot water to multiple outlets at the same time, making them a good choice for larger homes.

Regular boilers — also called conventional or heat-only boilers — work with both a hot water cylinder and a cold water tank in the loft. They are less common in new installations but may be the right choice if you are replacing an existing regular boiler and do not want to change the whole system.

If your property is not connected to the gas network — common in rural parts of Suffolk — an oil-fired boiler is likely your best option. PROTEC Plumbing installs and services oil boilers from leading manufacturers including Warmflow and Grant, and our engineers are OFTEC registered.

We install boilers from manufacturers we trust, including:

Baxi — A well-established British brand with a strong reputation for reliability and good parts availability. Baxi boilers come with competitive warranties and are a popular choice for both gas and combination applications.

Warmflow — Specialists in oil-fired boilers, Warmflow products are well regarded for their build quality and efficiency. A strong choice for rural properties off the gas network.

Grant — Another respected name in oil boiler technology, Grant offers a range of highly efficient condensing oil boilers suitable for a wide range of property types.

We will always recommend the boiler that is right for your home and budget — not simply the most expensive option.

Boiler output is measured in kilowatts (kW). Getting the right size is important — too small and the boiler will struggle to heat your home; too large and you will be paying for capacity you do not need.

As a rough guide:

• Small flat or 1–2 bedroom home: 24–27 kW
• 3–4 bedroom home: 28–34 kW
• Large home with multiple bathrooms: 35–42 kW

A proper heat loss calculation — which takes into account the size of your home, insulation levels, and hot water demand — will give you a much more accurate figure. PROTEC Plumbing carries out a free survey before any installation to make sure we recommend the right boiler for your property.

Before any work begins, one of our engineers will visit to assess your current system, discuss your requirements, and recommend the most suitable boiler. This is free and carries no obligation.

A straightforward boiler swap — replacing a like-for-like combi boiler in the same location — typically takes one day. More complex installations, such as moving the boiler to a different location or converting from a regular to a combi system, may take two days.

On the day, our engineer will:

1. Drain down and remove the old boiler
2. Make any necessary pipework modifications
3. Install the new boiler and connect it to the gas supply, flue, and heating system
4. Flush the system to remove any sludge or debris
5. Commission the boiler and test the full system
6. Register the boiler with the manufacturer for warranty purposes
7. Walk you through the controls and answer any questions

You will receive a Building Regulations compliance certificate (Gas Safe registration), the manufacturer's warranty documentation, and a full handover of the controls. We will also advise on the best settings for efficiency and comfort.

A new boiler is a significant investment, and we understand that the upfront cost can be a concern. We offer finance options to help spread the cost — ask us for details when you get in touch.

PROTEC Plumbing installs boilers throughout Ipswich and the wider Suffolk area. We offer free, no-obligation surveys and honest advice — we will tell you if a repair makes more sense than a replacement.

Call us on 01473 561159 or use our contact form to arrange a survey. We are Gas Safe and OFTEC registered, and all our installations are fully compliant with current Building Regulations.