How to Range Rate a Boiler - Viva Training Centre

Range rating a combi gas boiler is good for the customer, the environment and for the appliance!

In this video Worcester Bosch’s technical trainer, Rob takes a look at range rating.


Range Rating a Boiler

Welcome to another training video with Viva Training.

We have a great relationship with Worcester Bosch and Rob from Worcester Bosch their technical trainer has come to tell you all about range rating and range rating the Worcester Greenstar 8000.

Range rating can save your customer money on their central heating bills. As you know all homes have a heat loss value, back in the day this was worked out by your grandfather’s father’s forefathers taking a tip measure into a property working out the insulation values for that home by measuring the windows floors ceiling heights and then at the end of the day they
would input all that information into amir’s calculator and come out with a heat loss value for that property.

Today we measure that heat loss as a kilowatt output. In the modern world with the technology that we have available to us, we can now tune our gas appliances to match what that heat loss value is and what the property actually needs in heating energy in kilowatts.

When an installer sizes a boiler for a property they are sizing that boiler on the litres per minute that that come out of the hot tap.

Here we have a Worcester Greenstar 8000. This is the 30 kilowatt version and will do around about 10.7 litres a minute with a 40 degree delta T between hot and cold. Delta T basically means temperature difference.

Who benefits from range rating?

Number one, it’s the end user who will benefit from range rating because you’re going to save them money on their heating bills. Number two you’re also going to save their carbon footprint, which a lot of people are very conscientious about. And thirdly you are going to save them repair costs in the future of that appliance.

When we’re rage rating we’re actually changing the output of the the fan that’s working away inside the boiler. So we’re reducing the fan speed in effect, which will have the added effect
of not overworking the fan when it doesn’t need to overwork.

The heat exchanger will be able to work more effectively and manage the amount of heat that’s been transferred into it because there’s not as much gas going through there. The other benefit is to the planet, if we can help save our environment and go a bit greener and and help with the effects of global warming just by adjusting some settings on on our boiler.

How does range rating work?

If you do not range rate a boiler it’s going to be working at full tilt, all the time whenever you turn your heating on.

This boiler gives out 30 kilowatts of heating output to the central heating circuit. I am going to use today this 30 kilowatt 8000 as an example:

The property only needs 13 kilowatts of heating output. Central heating with a family is one of the most used modes for that for that appliance which could mean there is a big difference
between how the central heating and hot water demands is.

What we would do in this scenario is adjust down the heat output only for the central heating as we don’t want to affect the hot water output at all, because the boiler has been sized for what the water output needs is (how many litres a minute we have coming out of the tap).

Using the display, coupled that with the manufacturer’s instructions for this boiler we look at the display percentage. Display percentage relates to fan speed.

Looking at the chart, 50% is 15 kilowatts of heating output. Now we can go into the display and change this setting.

Once the display is awake we can access the service menu for this boiler and the service menu is there for engineer use. It’s there to tune the boiler to the property’s needs there are many
functions in the service menu for the installer.

To access the service menu on this boiler. Hold down the heating and the hot water buttons for a few seconds. The display will give us a countdown, when ready we want to go to the settings menu.

Press Okay

You’ll see a list of various different sub menus, but what we’re trying to we’re trying to change the heating output, so we want to select the heating menu.

At the very top of this submenu we have maximum heat output, press okay on maximum heat output – it will display the current percentage the boiler is giving out.

Hold down the arrow buttons until the display is showing that 50% that we wanted according to the heating output chart. Once happy press Okay.

If you don’t have any other parameters to change you can go all the way back to the start and that’s it. This boiler is now range rated and set up for the heat requirements that the property needs.

About Viva Training

At VIVA Training, we provide a range of gas training courses.

From our location in Halifax, we provide certification for gas operatives throughout England via bespoke courses that match your needs. So whether you’re an engineer who has enrolled onto our ACS course to remain up to date with the latest changes in the industry, or are a complete novice who has joined our Managed Learning Programme to start your journey to becoming a gas safe registered engineer, we want to give you the insights, skills, knowledge, tools and techniques to help you truly thrive.


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