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Combi Boilers

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Choosing the right new combi boiler for your home with PlumbProud

Combi boilers are the heart of more central heating systems in the UK than any other type of boiler. And you can order the best combi boilers on the market from 18 different trusted manufacturers here at Plumbproud.

On this page, we list the top 10 combi boilers available in Britain now according to the exclusive PlumbProud rating scheme. If you’re working to a budget, please click here to find out the cheapest combi boilers available at PlumbProud right now.

We’ll also explain what combi boilers are, how they work, what they cost, and how long they take to install.

Already know about combi boilers and want to see what we consider to be the best combi boilers on the market right now? Just scroll down.

To find out more about our range of brand new modern combi boilers and choosing the right one for your home, please call us on 01604 343053 or enter your postcode into one of the response forms on this page and click “SEND”.

What are combi boilers?

A combi boiler, short for “combination boiler”, is the most popular type of central heating boiler found in British homes. They’re also the newest.

Combination boilers were invented by boiler manufacturers in the 1970s to solve one particularly British problem – UK homes are some of the smallest in the world.

Heat only boilers require a hot water cylinder to store hot water and system boilers require both a hot water cylinder and a cold water tank. Where we people going to put them?

People still need heating and hot water even in the smallest apartment and the combi boiler was the answer they come up with.

Designed to be a compact unit that could, in many cases, be hidden behind a kitchen cupboard, British homeowners, landlords, and developers took to them straight away. And the technology behind combi boilers just keeps on getting better and more efficient meaning lower customers’ energy bills.

How does a combi boiler work?

We’ve seen that combi boilers don’t need a hot water cylinder or a cold water tank so where exactly is the water that it uses stored?

Well, it’s not actually stored anyway. A combi boiler draws water directly from the mains water supply. When you turn on a hot water tap or your radiators are switched on, it heats up the water it’s taken from the mains instantly. It’s just like one of those taps you see advertised on television which, if you want, can deliver piping hat water straight away.

Here’s how a modern combi boiler works.

Within your combi boiler, there’s a little trigger which tells it when you want hot water. When the trigger goes off, your boiler starts burning fuel whether that’s gas, electric, oil, or LPG.

There are two heat exchangers in your boiler – one heat exchanger is linked to your radiator and the other heat exchanger to hot water supply. In a few second, the exchangers get so hot that they heat up the water you want and then your boiler pumps it to where it’s needed.

It’s come full circle too. In recent years, some manufacturers have started to produce combi boilers with small internal hot water cylinders so it’s like a cross between a combi boiler and a heat only boiler.

How to choose the best boiler for your home

There are hundreds of different central heating combi boilers on the market right now so how can tell which is the right one for you? Budget is always a factor but let’s put that to one side for a moment.

First, you’ve got to consider “boiler size”. When heating engineers talk about boiler size, they’re not talking about its physical dimensions like how tall, wide, and deep a particular unit is. They’re talking about its power.

In this case, size is measured in something called “kilowatt (kw) outputs”. That tells you the amount of power a boiler has to heat water on demand. The higher the output, the more water it can heat.

For smaller properties, look for a boiler whose output is up to 27kW. For medium-sized properties, something between 28kw and 34kw will do.

For the largest properties, you’ll need something with 35kw or more. However, your PlumbProud engineer might recommend a heat only or system boiler instead particularly if you and your family have lots of radiators and multiple bathrooms.

PlumbProud note – electric combi boilers are more efficient so the boiler size you’ll need is different than for a gas combi boiler or an oil combi boiler.

Another thing to think about is “flow rate”. The higher the flow rate, the more water can pass through the boiler to get to your taps and radiators. However, if the water pressure is low in your area, having a boiler with a fast flow rate won’t make any difference.

Choosing the right boiler is important and it’s best to get the advice of a trained central heating system engineer. To arrange a visit, please call us on 01604 343053 or enter your postcode into one of the response forms on this page and click “SEND”.

How long does a combi boiler installation take?

If you’re replacing your old combi boiler with a new one and there’s no piping work being done, then it should take no more than 4-6 hours.

If you’re switching from a heat only boiler or system boiler to a combi boiler, this might take a couple of days. That’s also the same if you’re moving your combi boiler to a different position within your home.

What do combi boilers cost?

Boiler prices vary according to the model you choose and the complexity of your installation.

But the cheapest combi boiler on a standard, non-complicated installation offered by PlumbProud starts at around just £1,500.

We’re also a credit broker which means that, if you don’t have the money up front, you can spread the cost over a number of years. We also may be able to offer you an interest free option.

Top 10 boilers

1. Vaillant ecoTEC Plus 825

Our score rating: 93.35%

Efficiency rating
94%
Band rating
A
Output in kW
25.4 kW
Height
720 mm
Width
440 mm
Depth
338 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,300

2. Vaillant ecoTEC Plus 832

Our score rating: 92.98%

Efficiency rating
94%
Band rating
A
Output in kW
31.8 kW
Height
720 mm
Width
440 mm
Depth
338 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,300

3. Worcester Bosch Greenstar 2000 25kW

Our score rating: 92.89%

Efficiency rating
93%
Band rating
A
Output in kW
25 kW
Height
724 mm
Width
400 mm
Depth
300 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £1,800

4. Viessmann Vitodens 050-W 29kW

Our score rating: 92.66%

Efficiency rating
93%
Band rating
A
Output in kW
29 kW
Height
707 mm
Width
400 mm
Depth
350 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £1,800

5. Vaillant ecoTEC Plus 835

Our score rating: 92.60%

Efficiency rating
94%
Band rating
A
Output in kW
35 kW
Height
720 mm
Width
440 mm
Depth
372 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,400

6. Worcester Bosch Greenstar CDi Compact 28

Our score rating: 92.57%

Efficiency rating
90.5%
Band rating
A
Output in kW
28 kW
Height
680 mm
Width
390 mm
Depth
280 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,000

7. Vaillant ecoFIT Pure 825

Our score rating: 92.39%

Efficiency rating
94%
Band rating
A
Output in kW
25 kW
Height
700 mm
Width
390 mm
Depth
295 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,000

8. Vaillant ecoTEC Plus 838

Our score rating: 92.16%

Efficiency rating
94%
Band rating
A
Output in kW
38.7 kW
Height
720 mm
Width
440 mm
Depth
406 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,500

9. Vaillant ecoTEC Exclusive IQ 835

Our score rating: 91.90%

Efficiency rating
94%
Band rating
A
Output in kW
35 kW
Height
720 mm
Width
440 mm
Depth
406 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,600

10. Vaillant ecoTEC Pro 24

Our score rating: 91.77%

Efficiency rating
94%
Band rating
A
Output in kW
23.4 kW
Height
720 mm
Width
440 mm
Depth
338 mm
Mounting
Wall
Fuel
Gas
ERP Rating
A

Supply and installation around £2,000

Combi boiler FAQ

Free advice and support from our central heating experts

PlumbProud fits hundreds of new combi boilers into British homes every week and we’d really like the opportunity to give you a quote.

To help choose the right combi boiler for your home, please call us on 01604 343053 or enter your postcode into one of the response forms on this page and click “SEND”.

Combi boilers

Choose from the UK’s biggest range of combis

Heat only boilers

The ideal boiler perfect for the largest homes

System boilers

Ideal for 3+ bedroom, 2+ bathroom homes

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