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.