What type of boiler is the Worcester Bosch Greenstar Heatslave II 18/25?

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.

In many properties, combi boilers are more suitable than traditional types of boiler. Combi boilers heat water instantly on demand, which they draw directly from the mains supply, removing the need for storage tanks that can take up valuable space in your home.

A combi boiler is often the right choice for a smaller property, particularly if your home doesn't have a useable loft. As water is heated and delivered immediately rather than being kept warm for hours in an immersion tank, combi boilers reduce oil usage, thereby minimising your heating costs.

The main disadvantage of combi boilers is that they can only heat a certain amount of water at any one time. This means that, if two people are using different taps or showers within your home at the same time, the flow of heated water to each will be reduced, as will the water pressure and temperature.

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

Most Gas Safe engineers would suggest that the most suitable type of property for installing a Worcester Bosch Greenstar Heatslave II 18/25 combi boiler would be 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 18/25 Combi boiler's flow rate is 18 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.

What are the dimensions of the Worcester Bosch Greenstar Heatslave II 18/25 boiler?

The Worcester Bosch Greenstar Heatslave II 18/25 measures 855 mm in height by 520 mm in width by 600 mm in depth.

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.

If you are considering replacing your current heat only or system boiler with the Worcester Bosch Greenstar Heatslave II 18/25, please be aware that this will involve removing your hot water cylinder and/or expansion tank.

For guidance and further information, please contact the team at PlumbProud who will be happy to help you make the right choice.

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.

How energy efficient is the Worcester Bosch Greenstar Heatslave II 18/25 combi?

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.

We generate 14% of UK greenhouse gas emissions through centrally heating our domestic properties. Gas boilers are mainly responsible for harmful nitrogen dioxide emissions in larger British cities.

Will installing a Worcester Bosch Greenstar Heatslave II 18/25 combi be a positive contribution to the environment? Let's see what the experts say.

Boilers manufactured or supplied to UK domestic properties must achieve a legal minimum energy efficiency rating of 92% (equivalent to a good "A" grade using the SEDBUK scale). Prior to this, the minimum was 88% (88% and 89% are a "B" SEDBUK grade and anything 90% or above is an "A" grade).

The energy efficiency rating of a boiler refers to the amount of energy it uses to perform its everyday functions as well as the amount of energy it wastes.

The Worcester Bosch Greenstar Heatslave II 18/25 has been given a rating of 90% for energy efficiency, equivalent to a SEDBUK "A" rating.

The Energy Related Products Directive (ERP) was introduced in 2015 and it applies to all products that consume energy throughout their lifetime, including during the manufacturing process and at the point of final disposal.

The purpose of the ERP is to ensure that companies create products that are kinder to the environment by reducing both the energy they use and the harmful emissions they produce.

The Worcester Bosch Greenstar Heatslave II 18/25 has an ERP rating of "A" for heat and "B" for hot water production.

Is this Worcester Bosch Greenstar Heatslave II 18/25 combi covered by a warranty?

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