New Boiler Checklist Surrey (2026) | RCB Plumbing
Let’s be honest, shopping for a boiler is about as fun as watching paint dry—only much, much colder. It’s a grudge purchase. Nobody wakes up on a Saturday morning excited to spend their hard-earned money on a metal box that hangs on the wall. But when your current system gives up the ghost right in the middle of a chilly British winter, suddenly that metal box becomes the most important thing in your home.
The sheer volume of options can leave your head spinning. You’re bombarded with jargon like "kW output", "condensing combi", and "weather compensation". It is incredibly easy to overspend on a system that is too big for your home, or worse, under-spend on a cheap unit that fails exactly when you need it most. That’s why our team sat down and put together this straightforward guide to help you cut through the noise.
If you just want a reliable new boiler checklist to follow, you are in the right place. We will walk you through everything from working out which system fits your property to choosing a local installer you can actually trust. And, of course, if you live around Surrey and want us to sanity-check your options, we’re always happy to have a chat and point you in the right direction.
Quick 'before you start' checklist
Before you start calling up installers for quotes, take five minutes to gather the following details. Having this information ready will make your life significantly easier:
Current boiler type and age: Is it a combi, system, or regular boiler? Roughly how old is it?
Current issues: Are you getting constant pressure drops, strange banging noises, or total breakdowns?
Property size: How many bedrooms and bathrooms do you have?
Hot water demand: Do multiple people need to use the shower at the exact same time?
Location: Where is the current boiler located, and do you want it moved?
Budget and priorities: Are you looking for the longest warranty, the quietest model, or just the most budget-friendly fix?
Timeline: Is this a planned upgrade or an absolute emergency?
Keep this new boiler checklist handy. It helps any heating engineer give you an accurate, fixed price boiler quote right off the bat.
Step 1: Work out what type of boiler you’ve got
Before you can pick a replacement, you need to understand what is currently keeping your radiators warm. Heating systems generally fall into three main categories, and explaining them doesn't need to be complicated.
A combi (combination) boiler provides both heating and hot water directly from the mains. There is no need for a hot water cylinder or a cold water tank in the loft. They are compact, highly efficient, and incredibly popular.
A system boiler works alongside a hot water cylinder (usually kept in an airing cupboard). The boiler heats the water, and the cylinder stores it so you have a massive supply ready to go when someone turns on the tap.
A regular boiler (also known as a heat-only or conventional boiler) is the traditional setup. You will have a hot water cylinder in the cupboard and a cold water storage tank up in the loft.
If you aren't entirely sure what you have, don't worry. We’ll recommend the best fit after a proper look at your home and your daily water usage.
Step 2: Which new boiler do I need?
This is the golden question. "Which new boiler do I need?" is probably the first thing you typed into Google. The right answer completely depends on your property and lifestyle. Let's break down a simple decision pathway.
If you live in a flat or a house with one bathroom and limited storage space, a combi boiler is often your best bet. It saves space and provides instant hot water.
If you have two or more bathrooms, and your family has high simultaneous hot water demand (like running two showers on a busy Tuesday morning), a system boiler with a hot water cylinder is usually the smarter choice. A combi might struggle to keep the pressure up for both showers.
If you have an older, open-vented system with tanks in the loft, you might want to consider upgrading to a system or combi boiler to free up space. However, we always check your existing pipework first to ensure it can handle the higher mains pressure.
Step 3: Get the sizing right
When it comes to boilers, bigger isn't always better. Choosing the right size (measured in kilowatts or kW) is crucial. If you buy a boiler that is too small, your home will be freezing. If you buy one that is vastly oversized, it will be wildly inefficient, wasting gas and driving up your energy bills.
The ideal kW output depends on your home's insulation, the number of radiators, and your hot water demand. A small flat might only need a 24kW combi, while a large detached house with multiple bathrooms could require a 35kW system or higher.
To help your installer get this right, simply prepare a quick count of your radiators and note any planned extensions.
Step 4: Efficiency, running costs and what matters in 2026
Modern condensing boilers are highly efficient, meaning they extract as much heat as possible from the gas they burn. Upgrading an old, inefficient G-rated boiler to a brand-new A-rated model can noticeably reduce your monthly gas bills.
But the boiler itself is only half the story. The controls you use dictate your running costs. Adding weather compensation controls or a smart thermostat allows your heating to adapt to the actual temperature outside, rather than just blasting heat blindly. At RCB Plumbing, we frequently install smart heating controls because they offer such an easy win for your bank balance.
Step 5: Choose a brand and model
Picking a boiler brand can sometimes feel like choosing a football team—everyone has a strong opinion. We prefer to keep things balanced and professional.
Rather than arguing over the absolute "best" brand, we focus on reliability, the availability of spare parts, and the quality of the manufacturer’s customer support. We regularly install trusted, recognised brands like Worcester Bosch, Vaillant, and Glow-worm because they have proven track records. Choose a brand that offers a solid guarantee and fits your specific household requirements.
Step 6: Warranty, aftercare and servicing
This is the unglamorous bit that actually saves you money. A shiny new boiler might come with a 10-year warranty, but that warranty is completely void if you don't get the boiler serviced annually by a Gas Safe engineer. Think of it as a gym membership for your heating system—less glamorous, but highly effective for long-term health.
Annual boiler servicing catches minor faults before they become freezing emergencies. That’s exactly why we created the RCB Heating Club. Our care plans offer priority callouts, annual maintenance, and discounts on repairs, giving you total peace of mind throughout the year.
Step 7: Installer checklist
You can buy the best boiler on the market, but if it is installed poorly, you will have endless problems. Here is how to pick the right company in Surrey:
Gas Safe registration: This is a legal requirement and absolutely non-negotiable.
Clear written quotes: Ensure the quote includes everything (filters, system flushing, controls, and rubbish disposal).
Reputation: Look for real reviews on TrustATrader, Checkatrade, or Google.
Fixed pricing: Avoid hidden surprises.
This is exactly how we run our jobs at RCB Plumbing. We pride ourselves on transparent, fixed pricing, and we always leave your home clean and tidy. We even offer real-time engineer tracking so you aren't waiting around all day.
Step 8: Installation day and what to expect
A standard boiler replacement usually takes between one and two days. A good installer will communicate clearly before they arrive. Once on-site, they will drain your heating system, remove the old unit, and begin fitting the new pipework and boiler.
They will also perform a system cleanse or flush to remove old sludge from your radiators. Once installed, the engineer will test the system, commission the boiler, and hand over the vital paperwork, including your building regulations certificate and warranty registration.
Step 9: Questions to ask before you say yes
Don't be afraid to grill your installer before signing on the dotted line. Here is a handy bullet list of questions to ask:
What boiler type are you recommending and why?
What kW output do I need?
What heating controls are included in the quote?
Do we need a system cleanse or a full powerflush?
Is a magnetic system filter included to protect the new boiler?
What is the warranty length, and what do I need to do to keep it valid?
What is your aftercare plan if something goes wrong?
Surrey-specific considerations
Surrey has a fantastic mix of property types, from sprawling period homes in the villages to modern flats and heavily extended semi-detached houses. This means there is no "one-size-fits-all" approach to a Surrey new boiler installation.
Older period properties often need careful sizing to account for heat loss, whereas a new extension might require a larger kW output to run additional underfloor heating. Having a local Surrey installer means you get someone who understands these regional property quirks, and importantly, can offer a fast, same-day callout if things go wrong.
Summary: the checklist recap
To keep things perfectly scannable, here is your quick recap checklist:
Work out your current system type.
Calculate your hot water demand (simultaneous showers).
Find the right kW size for your radiators.
Choose an efficient model with smart controls.
Pick a reliable brand with a good warranty.
Commit to annual servicing (like our RCB care plans).
Only use a Gas Safe registered installer with fixed pricing.
Frequently asked questions
How do I know it’s time to replace my boiler?
If your boiler is over 10-15 years old, breaking down regularly, making odd banging noises, or your radiators take hours to heat up, it is likely time for a replacement.
How to pick a new boiler without overpaying?
Get a fixed price boiler quote from a reputable local installer rather than a massive national chain. Ensure the quote includes filters and flushing so you aren't hit with hidden costs on the day.
Which new boiler do I need for a 3-bed house in Surrey?
It depends heavily on your bathrooms. If you have one bathroom, a 28kW to 30kW combi boiler is usually perfect. If you have two bathrooms and a busy family, a system boiler is often better.
Combi vs system: which is better for two bathrooms?
A system boiler is generally better for two or more bathrooms because it stores hot water in a cylinder, allowing two showers to run at once without losing pressure.
What size boiler (kW) do I need?
This is based on your radiator count and insulation. Generally, a small home needs 24-27kW, a medium home needs 28-34kW, and a large home requires 35kW or more.
Do I need a powerflush when replacing a boiler?
Yes, your system should always be cleansed or flushed. Putting a brand new boiler onto dirty pipework full of black sludge will damage the new components and likely void your warranty.
How long does a boiler installation take?
A straightforward combi-to-combi swap usually takes one day. Changing from an old regular boiler to a new combi system can take two to three days due to pipework alterations.
What’s included in a proper boiler quote?
A proper quote includes the boiler, the flue, a magnetic filter, system flushing, necessary controls, Gas Safe registration, and the removal of your old boiler and rubbish.
Do you offer boiler care plans or servicing after installation?
Absolutely. We run the RCB Heating Club, which offers annual servicing, priority callouts, and repair discounts to keep your system in top condition.
Ready to get your heating sorted?
Choosing a new heating system doesn't have to be a headache. If you’re in Surrey and want a straight answer without a pushy sales pitch, get in touch with our team at RCB Plumbing.
Tell us your property details, and we’ll help you choose the right boiler for your home and budget. We provide clear, fixed-price quotes, same-day service where possible, and all our engineers are fully Gas Safe registered. Give us a call or book online today to arrange your consultation.
