What size boiler do I need for a 4 bedroom house?

As your home has four bedrooms, you would require a combi boiler with an output between 35-43kW. If you live in a medium sized home with up to 15 radiators, you would most likely need a 35kW boiler, whereas if you live in a large house with up to 20 radiators, you'll need a 43kW boiler.

How many radiators can a 30kW boiler run?

How Many Radiators Can a 30kW Boiler Run? For combi boilers, sizes from 28 to 32kW can keep between 10 and 15 radiators nice and toasty. On the other hand, 30kW heat only and system boilers can heat 15 to 20 radiators, making them the ideal choice for running larger properties.

How do I calculate boiler size needed?

An easy rule-of-thumb for BTU requirements is to figure that you need about 50 BTU per square foot of interior space in a cold climate; 35 BTU per square foot in a moderate climate; and 20 BTU per square foot in a hot climate.


Is a 30kW boiler big enough?

As a rough guide most apartments and smaller houses, with up to 10 radiators will require a 24-25kw boiler. A 28-30kw would be installed for a medium to large 3-4 bed house with up to 15 radiators, and a 33-35kw and a 40kw would be for a large house with anything up to 20 radiators.

What happens if a boiler is oversized?

Oversized boilers 'cycle' on and off excessively, i.e. they heat up too quickly, run for short blasts and then turn off because they are too hot. Each fire up is something close to full capacity which dumps a huge amount of heat into the system and overheats the radiators.


What size boiler do I need? (UK) | Boiler Size Calculator



Should I get a bigger boiler than I need?

The purpose of a boiler is to heat your home and provide hot water. So the larger your home and the more bathrooms you have the bigger the boiler you need. You want the boiler you buy to have enough power to heat all your rooms and supply enough hot water.

Is it better to get a higher kW boiler?

A kilowatt is a unit that defines how much energy your boiler outputs in the form of heat. As a general rule, the more heat and hot water you require for your home, the higher the kW boiler you will need.

How many radiators can a Worcester 30i run?

We also really love the fact the Greenstar 30i can supply 15 radiators in your home with hot water.

How many radiators can a 20 kW boiler run?

And for a heat only or system boiler: Up to 10 radiators: 12–15 kW. 10 to 15 radiators: 18–24 kW. 15 to 20 radiators: 30–40 kW.


Is my house too big for a combi boiler?

For a medium to large 3-4 bedroom house with up to 15 average size radiators, 1 bathroom and an ensuite* bathroom, a 28-34kw Combi Boiler would be installed. A 35kw and a 42kw Combi boiler would be for a large house with anything up to 20 average size radiators and 2 bathrooms*.

How do I know what boiler to buy?

You should consider how much hot water you and your family use, the size of your property, the fuel that is available to you, your existing system and the types of boiler you can have installed. You may also want to consider other factors such as energy efficiency and options for renewable energy use.

How many radiators will a 26kw boiler run?

If you have or want a system or regular boiler, they don't need to be as big as they incorporate a separate hot water cylinder for heating and storage of water for domestic use. So a boiler between 27 and 40kW output would be sufficient for up to 20 radiators.

Can I add more radiators to my boiler?

Putting in one or two extra radiators will probably be fine, though you should always check the capacity of your boiler in the manufacturer's manual before proceeding. If you wanted multiple extra radiators, it's very likely you'll need to upgrade your boiler as well.


Is the Worcester 30i a good boiler?

The Worcester Bosch i range is the company's most popular boiler range, thanks to its great design, excellent efficiency, ease of use and build quality. A Worcester 30i boiler is powerful enough to handle the central heating and hot water needs of a medium sized home with around 15 radiators and up to two bathrooms.

Is the Worcester 30i being discontinued?

The Greenstar 30i range is now discontinued, so if you'd like more information on the brand new Greenstar 4000, one of our expert engineers are more than happy to help.

How long should a Worcester Bosch boiler last?

How Long Should a Worcester Bosch Boiler Last? Typically, Worcester boilers last between 12 and 15 years, which is far longer than many other brands of boiler out there. If you want to extend the life of your boiler, we highly recommend having it properly maintained and serviced once in a while.

Can an electric boiler heat a 4 bed house?

The best system boilers for a 4 bed house will have an output rating of between 18 kW and 26 kW. Homes with more radiators (up to 15) will need an output rating closer to 26 kW. We've chosen to compare the Ideal Logic Max System S24 and the Vaillant ecoTEC Plus 624. Both of these are great options for a 4 bed house.


Is a combi boiler more expensive to run?

High Efficiency: Combi boilers are highly efficient. You can save money on your heating bills by switching from a conventional boiler to a combi boiler. More Affordable: The installation cost of a combi boiler is low as compared to a traditional heating system. Combi boiler parts are easy to find as well.

Is a combi boiler cheaper to run than a system boiler?

If we compare a system boiler vs combi boiler running costs, then it is likely that a combi boiler will be more efficient and so offer some savings. However, if a combi isn't able to provide the volume of hot water you need, then getting a combi boiler is pointless as it will not be able to heat your property.

How many radiators can 24kW boiler run?

A 24kW combi boiler can run ten household radiators. On the other hand, a 24kW system boiler can run up to 15 radiators. As a rule of thumb, experts calculated that one radiator requires about 1.5kWs.

How many kW does it take to heat a 3 bedroom house?

The average 3 bedroom home will require around 4-10 kW per day depending on how well the property is insulated. Combi boilers are offered in a range of sizes or power outputs ranging from 24 kW to 54 kW, however, this is for hot water. For heating, combi boilers offer much lower heat outputs of around 18 kW.


Do bigger radiators cost more to run?

Heat performance – double radiators are able to heat a larger space and faster. Energy costs – as double radiators are larger, they do cost slightly more in heating bills.
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