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Heat Pumps: Heading for a greener future

It's not just the heating and ventilation industry which is championing renewable energy products like heat pumps. It's the government and consumers too. Peter Gammon, technical product manager at MHS Boilers, believes the future could well be green. However, there's plenty to learn along the way. Here he takes a look at some of the issues around heat pumps and what the industry can do to make a difference
Heat Pumps: Heading for a greener future
AS I write this, the prime minister, Tony Blair has just finished speaking at the EU Summit on climate change. Celebrating the vision for 2020, he joined the growing clamour for renewable energy.

The legally binding agreement reached by the European Union will see member states reduce carbon emissions by 20% (below 1990 levels), increase the use of renewable energy by 20% and increase the use of biodiesel in transport by 10%.

The prime minister said: 'These are a set of groundbreaking, bold, ambitious targets for the European Union. It gives Europe a clear leadership position on this crucial issue facing the world.'

Well that's the big picture. What about on an everyday level? Wherever you look in the trade press, companies are launching renewable products - biomass boilers, solar hot water systems and heat pumps - in the variants ground, water and air source.

That's all good news for the environment and reduced reliance on fossil fuels but what about the knowledge of the heating and ventilation industry and specifiers? We believe it boils down to two simple words - education and engineering.

On the engineering front it is about looking for the right products, in the right combination to do the job in hand. There isn't really a simple way to specify renewable energy products like heat pumps - you can't just say you need an output of XkW and you want a heat pump to do the job. There are many variables and to get the correct system performing efficiently and effectively you need to take a few steps back. That's where the education kicks in.

MHS Boilers has been working with its European suppliers to deliver heat pumps across the range - air to water, ground source and water to water heat pumps which will deliver the kind of energy saving demanded by specifiers and end users.

Lower temperatures

Heat pumps can be used in many applications but as a general rule, the water flow temperatures they deliver are lower than that which is achievable using a boiler so they are usually best suited to use with underfloor heating systems and are ideal for heating swimming pools.

Some units are reversible so they may cool as well as heat, thus giving the possibility of providing comfort cooling via an underfloor system. Flow temperatures up to 65 -70ºC are possible with ground source and water source units but the higher the flow temperature the lower the Coefficient of Performance (COP).

Air source units are the simplest to install because there is no ground probes or earth collectors to install and there are versions that can be installed externally to the building.

Flow temperatures up to 55ºC can be delivered at outside air temperatures as low minus 8ºC, so air source units in the most areas of the UK are very viable heat generators.

Once you know the system and you know what kind of demand is being placed on the heat pump, you can work out which type will be best.

It's this bespoke approach that will deliver a truly energy efficient system. The technology is available to meet the heating demands of many buildings, particularly family dwellings using only renewable systems.

However, as you increase the demand placed on the system both efficiency and cost change. For instance, if you want to use solar collectors for hot water and provide space heating support to a heat pump, you need to decide where best to place the solar collectors.

It's not just a case of putting them on a south facing roof and hoping for the best. Their performance will be affected by the angle at which they are placed. So rather than having a gentle angle so they work at their best in the height of the summer, consider changing the angle to optimise their collection capacity to when the sun is lower in the sky in the winter months.

That way, when there is greater heating demand, the support of the heat pump by the solar system will be most effective.

The more demand placed on a heat pump, the more its COP will decrease. A ground source heat pump usually has a COP of around 4 - in other words for every 1kW of electrical energy used, 4kW of heating energy is produced.

To summarise, many things are possible with renewable energy and heat pumps. The technology is available and end users are starting to request it, but a little knowledge is a dangerous thing.

So our advice at MHS Boilers is to take the time to understand renewable energy products and how they interact with heating demand. That's why we work with both installers and specifiers to ensure that our heat pumps deliver both in terms of heating output and exceeding the end users expectations.


MHS Boilers: 01268 546700 or visit www.mhsboilers.com.
1 April 2007

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