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So, you’re looking for a new boiler. But it’s all so confusing.
What exactly is a gas boiler? What do you mean, “size”? Why are there so many boiler types?
Then you found hope in a boiler size calculator. It was great and all…
Until they start asking you about complicated engineering terms. Until they start quoting a fixed price even before you identify what is it that you need.
Then you’re lost again.
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No worries! That’s why we’re here! And we can give you replacement boiler quotes on any boiler you like. Let’s find out which size boiler you need real quick if you are unsure.
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Okay. To get straight to the point, the boiler size means the kilowatts (kW) needed. Not the physical size or different shapes.
Other than the cost of a new boiler which is a huge impact factor, choosing the best kW (or a.k.a the right size boiler) for you will depend on the following things:
Most households have 1 to 2 radiators in place. A general rule of thumb is to have 1 radiator for every 4 or 5m in the room.
Then again, the size of your radiator matters too. If it’s big enough, then perhaps 2 is just what you need.
You might know by now that choosing a new boiler or replacing an old gas boiler won’t be as easy as choosing new wallpaper.
But knowing the basics will make it less intimidating.
Here’s how to find the best boiler size for a great price.
Here’s our quick guide of recommended boiler sizes for certain homes. This isn’t written in stone but you won’t go far wrong with these figures.
Boiler Size | Boiler Type | Radiators | Bathrooms | Occupants |
upt to 29kw | Combi Boiler | Up to 9 | 1 | 1-4 |
30-45kw | Combi Boiler | 10-15 | 1-2 | 4-6 |
up to 20kw | System Boiler | up to 10 | 1-2 | 1-5 |
21kw – 40kw | System Boiler | 11-20 | 1-4 | 4-8 |
up to 20kw | Regular Boiler | up to 10 | 1-2 | 1-5 |
21-40kw | Regular Boiler | 11-20 | 1-4 | 4-8 |
Need something more specific? We’ve compiled a list of the manufacturers of their boiler models including their own guide and calculators too if you want to visit their respective websites:
If you’re already eyeing a brand, the official websites of these brands may also help you find a good fixed-price quote for your specific needs.
We also encourage you to research brand reviews to know the best deals and fixed prices for new models or repair rates before purchasing one.
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Before the size boiler, you’ll probably be asked for the type of boiler you are looking for first.
No need to scratch your head in confusion.
Here’s a quick rundown:
Calculating the right size combi boiler for your home is really simple with tools like our free online boiler quotation tool here.
It basically asks you how many bathrooms and showers you have so that we can work out what boiler you need from a few calculations.
Below are a few benefits and risks of purchasing a combi boiler for your home:
If you need a little help choosing the best combi boiler then the below boilers are some beauties:
Worcester Bosch 8000 Life and Style
Also known as a “regular boiler”, “heat-only boilers”, or the “traditional gas boiler”.
The water comes from a cold water tank, goes through heating, then stored in a hot water tank ready for use.
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A system boiler works like a conventional gas boiler, minus the cold water tank.
It heats and sources water directly from the mains, and stores them in a hot water cylinder.
You’re basically getting a good mix of the advantages from a heat-only boiler and a combi boiler. But if you’re a big fan of a combi boiler, this might not cut it for you.
Do a little self-assessment!
You should have a slight idea by now about the boiler type fit for your space.
But to find a good size boiler for you, under these types are more factors to consider such as:
Phew. It’s getting more complicated, isn’t it?
No worries. The next sections are simplified for you.
Here are a few things to remember before we proceed:
Combi boilers use more kW because they need more power for instant heating.
But how it works makes it more energy-efficient than a traditional gas boiler.
Because it also provides central heating, additional considerations such as how many bedrooms, how is the hot water demand, and additional showers can be very much helpful in finding the right size combi boiler.
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Since regular gas boilers are “heat only boilers”, the radiators (rather than bedrooms, bathrooms, and such) are the more important considerations.
Basically, more radiators would need a higher power.
Since system boilers more or less work like regular boilers, the radiator is also a good basis for deciding on the size system of this type.
We all know that finding a suitable size boiler is essential. That’s why you’re here.
But really, why?
One of the most asked questions is about undersizing or oversizing. Which is better?
Do you see where we’re going? The answer is neither. Both have their pros and cons, and the best recommendation is to really find the right size.
But if we’re simply talking about which is better, consider these instead:
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We hope you’re having a clearer grasp or probably looking at specific models by now.
You are? Great!
But there are some more factors you might want to throw into the equation for better accuracy. And an extra knowledge won’t hurt!
Other than the size of the home and the number of radiators, it’s also important to understand how fast heat dissipates in your space.
Especially with a system or conventional/regular gas boiler that stores water, a well-insulated place is needed.
Unlike a combi boiler that heats up the water right then and there, a system and conventional boiler will rely on the water tank.
Aside from the number of bathrooms, the bathtubs and showers boiler size also differs.
This has to do with the flow rate term you’ve probably been encountering.
Essentially, stronger water pressure will demand more power. This is a good consideration, especially for combi boilers.
Even if it ticks off the list above, expect a smaller size combi boiler to have slower and less water pressure.
One of the concerns with a traditional gas boiler is that it requires and wastes a lot of energy.
Aside from shooting up your bills, the constant transferring from cold to hot water and the use of gas aren’t exactly environmentally friendly.
This is also why many are opting to slightly transition from a traditional regular boiler to the greener combi boiler, or completely switch from a gas boiler to modern boilers.
An example of a modern boiler is the Hybrid Boiler.
If you want to opt for greener options, choose a Condensing Boiler. The heat is recycled and reused, as opposed to a Non-Condensing Boiler that burns the gases using fuel.
If you noticed, the use of gas boilers – or anything gas actually – is not as supported nowadays because of its carbon footprint.
If you have the chance, you may want to read up on the best electric boilers here.
If you’re getting a totally new boiler, great. Just follow all the tips thus far and get a good size boiler quickly.
But if you’re coming from a particular boiler type and changing to a new boiler type, you don’t really have much choice unless you’re willing to go through big adjustments and new pipeworks.
What do we mean?
Get the best boiler deals, fitted next day if ordered before 2pm weekdays!
Of course, don’t forget to include the repair costs in your decision-making process.
Don’t blow off everything into purchasing a new boiler, but end up struggling to maintaining it and then not being able to use your trusty gas boiler at all when you need it the most.
As mentioned, your manufacturers are likely to give a decent fixed price for repair and tests.
It helps, though, to initially assess the condition of your boiler on your own before asking for professional help.
Here are some things you can look out for:
The hunt for a new boiler is already taxing as it is.
Especially if taking into account the installation, but that’s why we have devised our online boiler comparison system.
In just a few clicks you can get prices on boilers perfect for your home. you can even spread the cost with boiler finance!
But trust us, it pays to have your own knowledge about the basics of a gas boiler before you make big decisions.
That, mixed with expert opinions, will make it so much easier for you to find the right boiler for a great price.
You still know your household best after all, and the best boiler should be the one that will suit you and your family’s needs in the most perfect way possible.
Get the best boiler deals, fitted next day if ordered before 2pm weekdays!
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