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Worcester Bosch Greenstar Heatslave II External 12/18 boiler

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Plumbproud rating

75.95%

Worcester Bosch Greenstar Heatslave II External 12/18 Combi Oil boiler

We score this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler as 75.95% on the PlumbProud quality scoring system. Our rating is based on various factors, including the installation price, the length of the manufacturer's warranty, and the expected energy efficiency and operating costs.

Provided the proposed installation is straightforward, we would anticipate that this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler will cost £3,700 fully installed through PlumbProud.

For a free quote on the Worcester Bosch Greenstar Heatslave II External 12/18 boiler and to get professional advice and guidance on whether it is the right choice for your home, please enter your postcode in the quote boxes on this page, click here to email us, or call us on 01604 343053.


Installed price around

£3,700

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Worcester Bosch Greenstar Heatslave II External 12/18 Combi Oil boiler frequently asked questions

Worcester Bosch Greenstar Heatslave II External 12/18 - a regular boiler, combi boiler or system boiler?

When looking for a combi boiler for your house or flat, the Worcester Bosch Greenstar Heatslave II External 12/18 might be a suitable option for you.

Combi boilers are excellent for providing hot water and heat for your radiators just when you need it. When you have a combi boiler installed in your home, you just turn on the tap and the hot water for your bath, shower, washing dishes and other activities is there when you need it. It also provides the heat you need to keep your radiators warm.

A combi boiler heats the cold water passing through it, which it draws from the mains. This newly heated water can then be distributed to whichever hot tap or radiator needs it.

In the past, boilers needed at least one storage tank to hold water that was either already heated or would be heated later. Sometimes, you'd have to wait for hot water because there was none left. In addition, storage tanks took up a lot of space and most UK homes are pretty small.

The main disadvantage to combi boilers is that they can only heat a certain amount of water at any one time, meaning the pressure, volume and temperature of water will decrease if more than one tap is on at the same time or if both the shower and washing machine are on together.

Is the Worcester Bosch Greenstar Heatslave II External 12/18 combi boiler suitable for my house or apartment?

Selecting the right boiler for your home means choosing a boiler that is the right size. And, by size, we don't mean how big it is, we mean how powerful it is - the "output".

Your boiler’s output is a measurement of the power it has available to it to heat the water you need for your radiators or for when you turn on a tap, bath or shower. A higher output rate means it has more power and can heat more water.

It's important to choose an output that matches the demand for water in your home because if your boiler has too low an output, you'll often find only lukewarm water comes out of your taps or heats your radiators. If it’s too high, you’ll be paying more for your oil than you need to.

The Worcester Bosch Greenstar Heatslave II External 12/18 combi has an output of 18 kW, so which types of property would this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler be appropriate for?

A PlumbProud heating engineer would recommend that this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler is suitable for smaller homes and apartments with up to 10 radiators and one bathroom.

As well as the output rate, you need to consider "flow rate" when choosing a combi boiler.

The flow rate describes how much water a combi boiler can draw from the mains, instantly heat, and then send to your radiators. Flow rates are measured in litres per second and this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler's flow rate is 15 L/m.

The water in your mains pipe also has its own flow rate - normally between 10 and 12l/m in most parts of Britain. This means that, if you choose a combi boiler with a flow rate of 17l/m where local water pressure is 11lm, it won't actually process more water because of the slower flow rate of the mains.

In addition, larger households with more than one bathroom, multiple radiators, and where family members may want to use hot water at the same time (like morning showers) may actually need a boiler with a higher flow rate than either the boiler or the local mains pipe.

When our engineer comes out to quote you, they may recommend that you choose a heat only boiler or system boiler instead if your family's demand for hot water is higher than normal.


What is the size of the Worcester Bosch Greenstar Heatslave II External 12/18?

The Worcester Bosch Greenstar Heatslave II External 12/18 is 950 mm [H] by 640 mm [W] by 770 mm [D] in size.

Floor-standing external combi boilers like the Worcester Bosch Greenstar Heatslave II External 12/18 are housed in a strong weatherproof casing that protects them from rust and water ingress - they also offer much easier access for heating engineers if there is a fault or a repair is needed.

The risk of internal oil leaks and the damage and unpleasant odours they cause is also removed, as is the threat to your family's safety in the event of a carbon monoxide escape (the gas will simply disperse harmlessly into the atmosphere).

Is the Worcester Bosch Greenstar Heatslave II External 12/18 a non-condensing or condensing boiler?

The Worcester Bosch Greenstar Heatslave II External 12/18 is a condensing oil boiler - this is the type of boiler we recommend to most clients because they're better for the environment and they will save money on annual fuel bills.

A condensing boiler captures and recycles the warmth still present in both the flue exhaust gases and water vapour condensation created when oil is burned to provide your boiler with power.

This means it needs less oil to operate and it uses this extra energy to perform a number of tasks, including heating the colder water that comes back to the boiler from the radiators in your home.

Is the Worcester Bosch Greenstar Heatslave II External 12/18 combi boiler rated as environmentally friendly?

With more and more of us concerned about environmental issues and climate change, how we heat our homes has become an important issue to many homeowners.

14% of the total amount of greenhouse gases produced by the UK comes from the central heating systems we use. In some of Britain's biggest cities, gas boilers create dangerous levels of nitrogen dioxide in the atmosphere.

Would installing a Worcester Bosch Greenstar Heatslave II External 12/18 combi boiler in your home be a green choice? Let's look at the numbers.

The energy efficiency rating of the Worcester Bosch Greenstar Heatslave II External 12/18 is 90% with a SEDBUK band rating of "A".

Energy efficiency tests record how much energy is wasted on non-core functions during an operation.

By law, all boilers manufactured and supplied in the UK must have a minimum energy efficiency performance level of 92% (equivalent to a SEDBUK "A" grade). Up to April 2018, the minimum performance level was 88% (88% and 89% are equivalent to a SEDBUK "B" grade and 90%+ an "A" grade).

The Energy Related Products (ERP) Directive is important European legislation that aims to limit energy use and harmful gas emissions during the manufacturing process, when the product is in use, and after it is disposed of.

For the Worcester Bosch Greenstar Heatslave II External 12/18, the ERP Heat rating is "A" and the ERP Water rating is "B".

How many years' warranty does the Worcester Bosch Greenstar Heatslave II External 12/18 combi come with?

A parts and labour warranty of 2 years is included when you purchase the Worcester Bosch Greenstar Heatslave II External 12/18 boiler through PlumbProud.


Worcester Bosch Greenstar Heatslave II External 12/18 Oil Combi boiler specifications

Powered by GasOil
LocationExternal
Condensing?Yes
Efficiency rating90%
Band ratingA
LPG Compatible?No
P/L Warranty2 Years
Output in kW18 kW
Height950 mm
Width640 mm
Depth770 mm
MountingFloor
Flow rate15 L/m
ERP HeatA
ERP WaterB

The top 10 rated Oil Combi boilers

Using the Plumbproud scoring system, the current 10 ten Oil Combi boilers assessed using a number of important variables are as follows:

1Worcester Bosch Greenstar Heatslave II 12/1876.19%
2Worcester Bosch Greenstar Heatslave II 18/2576.12%
3Worcester Bosch Greenstar Heatslave II External 12/1875.95%
4Worcester Bosch Greenstar Heatslave II 25/3275.83%
5Worcester Bosch Greenstar Heatslave II External 25/3275.58%
6Grant Vortex Pro 2167.46%
7Grant Vortex Pro 2667.43%
8Grant Vortex Pro 26kW67.35%
9Grant Vortex Pro 2167.31%
10Grant Vortex Pro 2667.14%

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Worcester Bosch Greenstar Heatslave II External 12/18 boiler

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Worcester Bosch Greenstar Heatslave II External 12/18 Combi Oil boiler

  1. Home
  2. Worcester Bosch Greenstar Heatslave II External 12/18
Plumbproud rating for this boiler
75.95%

Our PlumbProud boiler quality benchmark tests score this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler at 75.95%. Several factors go into determining our rating including installation costs, manufacturer guarantees, energy efficiency, running costs, and more.

You should budget approximately £3,700 for the supply and installation of this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler on a standard, non-complicated fit.

To get a free quote for the installation of the Worcester Bosch Greenstar Heatslave II External 12/18 boiler in your home, simply enter your postcode in the box provided on this page. You can also find out whether this is the right boiler for your home by clicking to email our installation team or by calling us on 01604 343053.


Installed price guideline
£3,700

Get your free quote

Worcester Bosch Greenstar Heatslave II External 12/18 Oil Combi boiler specifications

Powered by GasOil
LocationExternal
Condensing?Yes
Efficiency rating90%
Band ratingA
LPG Compatible?No
P/L Warranty2 Years
Output in kW18 kW
Height950 mm
Width640 mm
Depth770 mm
MountingFloor
Flow rate15 L/m
ERP HeatA
ERP WaterB

Worcester Bosch Greenstar Heatslave II External 12/18 Combi Oil boiler frequently asked questions

What kind of boiler is the Worcester Bosch Greenstar Heatslave II External 12/18 - standard, combi or system?

You may wish to consider installing the Worcester Bosch Greenstar Heatslave II External 12/18 if you are looking for a combi boiler for your house or flat.

Traditional boilers have one or more large tanks in which they store either heated water or water to be heated later. Manufacturers originally introduced combi boilers to the market in the 1970s to enable homeowners to save space - UK residential properties are among the smallest in the Western world.

Combi boilers don't need these tanks because they draw water directly from the mains and instantly heat it on demand thanks to the technology inside the boiler. Combi boilers then distribute this hot water to your home’s taps and radiators when needed.

The most significant disadvantage of combi boilers is that they are not ideal in larger homes where multiple people might want hot water at the same time – for example, if someone is having a shower while another wants to wash dishes in the kitchen. This is because combi boilers have a maximum volume of water that they can heat. When two people want hot water at the same time, the water temperature, pressure and volume delivered to both points drop.

Is the Worcester Bosch Greenstar Heatslave II External 12/18 combi boiler from the Greenstar Heatslave II External range a suitable choice for my house or flat?

It's best to choose a boiler whose size or "output" is right for your property. With boilers, however, size does not mean how big a boiler is, it means how much power it has.

The output of a boiler is measured in kilowatts and tells you how much power it has available to heat the water it sends to your hot taps, showers and radiators. The greater the demand for hot water in your home, the larger the output you will need.

It is important to select a boiler with the optimal output rate. Choose one with too high an output and your oil bills will be too expensive. Choose one with too low an output and sometimes the water in your radiators and coming out of your taps will be barely lukewarm.

The output of the Worcester Bosch Greenstar Heatslave II External 12/18 combi is 18 kW kilowatts, so which types of property would this be most suitable for?

An experienced boiler engineer would recommend that this Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler would be a suitable installation choice for smaller homes and apartments with up to 10 radiators and one bathroom.

Flow rates are important when choosing a combi boiler as well as output rates.

A combi boiler's flow rate (measured in litres per minute) describes how much water it can instantly heat then distribute to the taps and radiators in your home - you will need to factor this into your decision on a new combi boiler. This Worcester Bosch Greenstar Heatslave II External 12/18 Combi boiler's flow rate is 15 L/m.

If you have a lot of radiators and bathrooms in your home and there's lots of demand within your household for hot water at the same time (like morning or evening showers and baths), you'll need a boiler with a high flow rate.

However, it's not quite that simple. If your local mains water pressure is low, you're not going to gain any benefit from choosing a combi boiler with a high flow rate because that higher flow rate doesn't mean it can draw more water from the mains pipes.
When our engineer comes out to quote you, they may recommend that you choose a heat only boiler or system boiler instead if your family's demand for hot water is higher than normal.


How large is the Worcester Bosch Greenstar Heatslave II External 12/18?

The dimensions of the Worcester Bosch Greenstar Heatslave II External 12/18 are 950 mm [H] x 640 mm [W] x 770 mm [D].

Floor-standing external combi boilers like the Worcester Bosch Greenstar Heatslave II External 12/18 are housed in a sturdy weatherproof casing to protect them from the elements, water ingress, and the risk of rust. Heating engineers also find external boilers much easier to access on repair and maintenance visits.

As the boiler is outdoors, there is less risk of an oil leakage into your home that can cause significant damage and leave your property with an unpleasant, hard-to-remove odour. In addition, there is far less danger to you and your family from carbon monoxide leakage as, in the event of a fault, the gas will disperse in the outside atmosphere.

Is the Worcester Bosch Greenstar Heatslave II External 12/18 a condensing or non-condensing boiler?

The Worcester Bosch Greenstar Heatslave II External 12/18 is a condensing oil boiler - where possible, we always recommend to clients that they choose one of the very latest condensing boilers to take advantage of this technology, which improves year after year.

Condensing boilers are more energy-efficient as they capture and recycle the heat contained in flue exhaust gases and water vapour condensation. They then use this heat to perform tasks like warming up colder water returning to the boiler from the radiators.

By choosing a condensing boiler, you'll help the environment as well as save money on your oil bills.

Is the Worcester Bosch Greenstar Heatslave II External 12/18 combi boiler an environmentally friendly choice?

Many homeowners are now worried about climate change and the damage they do to the environment from heating their homes has become a subject of increasing concern.

Gas boilers are responsible for dangerous atmospheric levels of nitrogen dioxide emissions in Britain's biggest cities and, overall, 14% of the UK’s greenhouse gases are produced by our domestic central heating systems.

Would choosing a Worcester Bosch Greenstar Heatslave II External 12/18 combi help the environment? Let’s see what the performance figures suggest.

Every boiler manufactured and supplied in the UK must have an energy efficiency rating of 92% (SEDBUK “A” rating). These minimums were made law in April 2018 - before that, the minimum energy efficiency rating was 88% (88%/89% = "B" SEDBUK grade, 90%+ = "A" SEDBUK grade).

The Worcester Bosch Greenstar Heatslave II External 12/18 was awarded an efficiency rating of 90% and a band rating of "A".

Energy efficiency ratings for boilers describe the amount of energy they use and waste when switched on and working.

In 2015, new legislation was introduced by the EU to encourage manufacturers to develop more energy-efficient products that emit fewer harmful gases throughout their lifetime.

The Energy Related Products Directive (ERP) applies to all products that consume energy, including during the manufacturing process, at the point of final disposal, and all points in between.

The ERP rating of the Worcester Bosch Greenstar Heatslave II External 12/18 is "A" for heat and "B" for hot water.

If the Worcester Bosch Greenstar Heatslave II External 12/18 combi boiler breaks down, am I covered?

The parts and labour warranty on the Worcester Bosch Greenstar Heatslave II External 12/18 lasts for 2 years.


The top 10 rated Oil Combi boilers

Using the Plumbproud scoring system, the current 10 ten Oil Combi boilers assessed using a number of important variables are as follows:

1Worcester Bosch Greenstar Heatslave II 12/1876.19%
2Worcester Bosch Greenstar Heatslave II 18/2576.12%
3Worcester Bosch Greenstar Heatslave II External 12/1875.95%
4Worcester Bosch Greenstar Heatslave II 25/3275.83%
5Worcester Bosch Greenstar Heatslave II External 25/3275.58%
6Grant Vortex Pro 2167.46%
7Grant Vortex Pro 2667.43%
8Grant Vortex Pro 26kW67.35%
9Grant Vortex Pro 2167.31%
10Grant Vortex Pro 2667.14%
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