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Worcester Bosch Greenstar Heatslave II 18/25 boiler

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Plumbproud rating

76.12%

Worcester Bosch Greenstar Heatslave II 18/25 Combi Oil boiler

According to our PlumbProud boiler quality scoring system, we rate this model 76.12%. We rank boilers using a number of different factors including price installed, manufacturer guarantees, energy efficiency, likely running costs, and more.

Fitted by an experienced Gas Safe PlumbProud engineer, the cost for this Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler will be in the region of £3,500 on a standard, non-complicated installation.

To receive a free quote on the Worcester Bosch Greenstar Heatslave II 18/25 boiler, as well as professional advice on whether it will meet the needs of your home, simply enter your postcode in the quote box on this page, click here to email us, or call 01604 343053.


Installed price around

£3,500

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Worcester Bosch Greenstar Heatslave II 18/25 Combi Oil boiler frequently asked questions

Worcester Bosch Greenstar Heatslave II 18/25 - a regular, combi or system boiler?

When looking for a combi boiler for your house or flat, the Worcester Bosch Greenstar Heatslave II 18/25 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 a Worcester Bosch Greenstar Heatslave II 18/25 combi 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.

A boiler’s output indicates the amount of power it can use when heating the water which it then sends to your taps and radiators. The higher the output rate, the more water it can heat.

If a boiler’s output is too low, there will be times when your hot water might not be as hot as you want it to be. If it is too high, you’ll likely be paying more than you need to for your gas.

Measured in kilowatts, the Worcester Bosch Greenstar Heatslave II 18/25 combi's output level is 25 kW, so which types of property would this Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler be an appropriate choice for?

An experienced boiler engineer would recommend that this Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler would be a suitable installation choice for smaller homes and apartments with up to 10 radiators and one bathroom.

Please remember too that all combi boilers draw water from the mains - they have no storage tanks. Combis heat the water from the mains on demand and then send it to wherever it's needed in the house, like a radiator, a bathroom or a kitchen.

The speed at which it can do this is called the "flow rate", which is measured in litres per minute. If you have a lot of radiators and bathrooms in your home and multiple people are regularly trying to use the hot water at one time, such as in the morning or evening, you'll need a combi with a high flow rate. This Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler's flow rate is 18 L/m.

However, it's not that simple. Combis can only draw water from the mains at the speed it's delivered. If the flow rate of the local water supply is 11l/m, you shouldn't purchase a boiler with a flow rate of 17l/m because it will never be able to use that extra capacity.

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.


The dimensions of the Worcester Bosch Greenstar Heatslave II 18/25 are

The Worcester Bosch Greenstar Heatslave II 18/25 is 855 mm high by 520 mm wide by 600 mm deep.

Floor-standing boilers can still be found in hundreds of thousands of properties in the UK - however, many homeowners are considering switching to wall-mounted units to create new living space for themselves and their families. Our engineers can replace your current floor-standing unit with a wall-mounted model, although please be aware that we may need to charge more if your current pipework needs replacing.

Your investment will be worth it as you'll more than cover the cost with the saving you make every year on your oil bills.

Please be aware that if you replace your existing heat only or system boiler with the Worcester Bosch Greenstar Heatslave II 18/25, you'll also need to remove your hot water cylinder and/or expansion tank.

Please contact PlumbProud for further advice if you are unsure how to proceed. Our friendly team will be happy to assist you in making the right decision.

Worcester Bosch Greenstar Heatslave II 18/25 – condensing or non-condensing?

The Worcester Bosch Greenstar Heatslave II 18/25 is a condensing oil boiler - in fact, we recommend that you select this model or one of the latest condensing boilers on the market as the technology continues to improve over time.

Condensing boilers capture the heat still present in the flue exhaust gases and water vapour condensation created when the oil is burned and they recycle this back into the heating system to warm up the cold water re-entering the boiler from your radiators.

They're much more environmentally friendly and installing one results in much lower annual oil bills.

Is the Worcester Bosch Greenstar Heatslave II 18/25 combi boiler rated as environmentally friendly?

Many homeowners are becoming increasingly concerned about how they heat their homes and the impact it has on climate change and other important environmental issues.

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.

Will installing a Worcester Bosch Greenstar Heatslave II 18/25 combi in your home be a positive contribution to the environment? The figures below will tell you more.

All boilers manufactured and installed in the UK are required by law to have an energy efficiency rating of at least 92%, equivalent to a good “A” rating on the SEDBUK scale. Before this, the minimum was 88% (ratings of 88% and 89% are equivalent to a high “B” SEDBUK rating and anything 90% or higher is an "A" rating).

A boiler's energy efficiency rating is designed to let you know how much energy is used and wasted during normal functioning.

The Worcester Bosch Greenstar Heatslave II 18/25 was given an efficiency rating of 90% and a band rating of "A".

The Energy Related Products Directive grades products according to the energy they consume and the harmful gas emissions they create, from manufacturing right through to final disposal, including how they're used by customers between these two points.

The Worcester Bosch Greenstar Heatslave II 18/25 is rated "A" for heat and "B" for water.

How long is the warranty period on the Worcester Bosch Greenstar Heatslave II 18/25 combi boiler?

A parts and labour warranty of 2 years is included when you purchase the Worcester Bosch Greenstar Heatslave II 18/25 boiler through PlumbProud.


Worcester Bosch Greenstar Heatslave II 18/25 Oil Combi boiler specifications

Powered by GasOil
LocationExternal
Condensing?Yes
Efficiency rating90%
Band ratingA
LPG Compatible?No
P/L Warranty2 Years
Output in kW25 kW
Height855 mm
Width520 mm
Depth600 mm
MountingFloor
Flow rate18 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 18/25 boiler

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Worcester Bosch Greenstar Heatslave II 18/25 Combi Oil boiler

  1. Home
  2. Worcester Bosch Greenstar Heatslave II 18/25
Plumbproud rating for this boiler
76.12%

Our PlumbProud quality scoring system uses many different factors, such as price installed, manufacturer guarantees, energy efficiency and the likely cost of running, among others, to determine a boiler's value for money rating. This Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler scores 76.12%.

This Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler is likely to cost around £3,500 fully installed by PlumbProud if there are no unexpected complications during the fit.

If you would like to get in touch with us for a free quote and professional guidance and advice on whether the Worcester Bosch Greenstar Heatslave II 18/25 is the right choice for your home, you can do so by entering your postcode in the quote boxes on this page, calling us on 01604 343053 or you can click here to email us.


Installed price guideline
£3,500

Get your free quote

Worcester Bosch Greenstar Heatslave II 18/25 Oil Combi boiler specifications

Powered by GasOil
LocationExternal
Condensing?Yes
Efficiency rating90%
Band ratingA
LPG Compatible?No
P/L Warranty2 Years
Output in kW25 kW
Height855 mm
Width520 mm
Depth600 mm
MountingFloor
Flow rate18 L/m
ERP HeatA
ERP WaterB

Worcester Bosch Greenstar Heatslave II 18/25 Combi Oil boiler frequently asked questions

Is the Worcester Bosch Greenstar Heatslave II 18/25 a standard, combi or system boiler?

Worcester Bosch’s Greenstar Heatslave II 18/25 is one you might consider if you’re looking for a combi boiler for your house or flat.

A combi boiler could be a better choice than a standard boiler if space is at a premium in your home. Combi boilers draw water directly from the mains supply and heat it instantly, removing the need for a hot water cylinder and a cold water tank.

Water is heated on demand and then distributed directly to your taps and showers. This means that combi boilers use less fuel and so reduce your oil bills.

The main disadvantage to combi boilers is that they can only heat a limited volume of water at any given time. If more than one tap or shower is in use, the hot water supply to both could be restricted and both the water pressure and temperature will drop.

Should I choose a Worcester Bosch Greenstar Heatslave II 18/25 combi boiler for my house or flat?

Whether this Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler is right for where you live depends on its size or "output" level. Size does not mean its physical dimensions - it means how powerful it is.

A boiler’s output is a measurement of the amount of power it can use to provide hot water to your taps and radiators. The higher its output rate, the more water it can heat.

If your new boiler’s output is too low, your hot water might not be as hot as you want it to be. If it's too high, you’ll be paying more for oil than you need to.

The output of the Worcester Bosch Greenstar Heatslave II 18/25 combi boiler is 25 kW, so which types of property would this be appropriate for?

An experienced heating engineer would say that this Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler's level of output makes it a suitable installation for smaller homes and apartments with up to 10 radiators and one bathroom.

When choosing a combi boiler like the Worcester Bosch Greenstar Heatslave II 18/25, you need to consider the "flow rate" as well as the output rate. Flow rates (measured in litres per minute) indicate the volume of hot water that the boiler can heat up and then distribute to your taps and radiators.

However, combi boilers draw water from the mains and this means they can only heat the amount of water that actually enters your property.

What this means is that, if your mains pressure is 12 litres per minute, that is your boiler's effective flow rate even if it has the capacity to process 18 litres per minute. This Worcester Bosch Greenstar Heatslave II 18/25 Combi boiler's flow rate is 18 L/m.

To give you an idea of the flow rate you might need, a power shower typically requires around 12 litres of water per minute and a basin tap requires 4-8 litres per minute.

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 18/25?

The Worcester Bosch Greenstar Heatslave II 18/25 boiler is 855 mm high, 520 mm wide, and 600 mm deep.

While a large number of properties in the UK still feature floor-standing boilers like the Worcester Bosch Greenstar Heatslave II 18/25, the more compact wall-hung models are now the preferred options for most homeowners keen for more living space for themselves and their families. It is possible to replace your floor-standing unit with a wall-hung and more compact boiler but please note that much of the pipework could need replacing, making the overall cost of installation higher.

Your new compact will save you money on your oil bills every quarter, however, and those savings should cover the costs within a few years.

You will also need to remove your hot water cylinder and/or expansion tank if you replace your current heat only or system boiler with the Worcester Bosch Greenstar Heatslave II 18/25.

Please get in touch with PlumbProud for information and advice on how to proceed and we'll provide you with our recommendations.

Worcester Bosch Greenstar Heatslave II 18/25 – condensing or non-condensing?

Condensing oil boilers like the Worcester Bosch Greenstar Heatslave II 18/25 are environmentally friendlier and cheaper to run so, if possible, we strongly recommend that you choose this or one of the very latest models.

Condensing boilers are much more efficient and economical to run because they contain a secondary heat exchanger that captures and recycles the warmth still present in the flue exhaust gases and the water vapour condensation for re-use, meaning that they use less oil to run.

Is the Worcester Bosch Greenstar Heatslave II 18/25 combi 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.

Central heating accounts for 14% of greenhouse gas emissions in the UK. In larger British cities, gas boilers emit dangerous levels of nitrogen dioxide into the atmosphere.

Would choosing a Worcester Bosch Greenstar Heatslave II 18/25 combi help the environment? Let’s see what the performance figures suggest.

An energy efficiency rating of 92% or above is a legal requirement for all boilers manufactured and installed in the UK today. 92% is equivalent to a low-to-middle "A" grade on the "Seasonal Efficiency of Domestic Boilers" (SEDBUK) scale.

Energy efficiency measures how much energy a boiler uses and wastes in the course of its normal operation. The lower the waste, the lower your oil bills.

The Worcester Bosch Greenstar Heatslave II 18/25 was awarded an efficiency rating of "90%", equivalent to a "A" rating on the SEDBUK system.

The ERP (or Energy Related Products Directive) is a European regulation governing products which require energy to operate throughout their lives and encourages manufacturers to create products that are more environmentally friendly.

The legislation is designed to reduce the potential for harmful gas emissions during manufacturing and actual use right through to the point of final disposal.

For the Worcester Bosch Greenstar Heatslave II 18/25, the ERP rating is "A" for heat and "B" for hot water production.

What warranty do I get if I purchase the Worcester Bosch Greenstar Heatslave II 18/25 boiler?

The Worcester Bosch Greenstar Heatslave II 18/25 is covered by a parts and labour warranty of 2 years following installation.


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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