Skip to main content

Tech made easy: Let’s talk about heat recovery systems

What we’re talking about: Heat recovery systems.

Why? They’re a great way of maximising the energy produced by existing heating and cooling systems. In doing so, they help you reduce carbon emissions and save money.

What are they? Anything that captures waste heat from domestic or industrial appliances and processes and re-uses it in some way. That includes appliances such as boilers, fridges, ventilation systems or any number of industrial systems that use heating and cooling.

How do heat recovery systems work? There are lots of different types but they all work on the same principal – a heat exchanger collects and transfers heat that would otherwise be lost from air or water, and recycles it for other uses.

When you say different types… Different in the ways they capture the heat. There are thermal wheels, plate heat technology, heat pumps, coil/closed loop systems, heat pipes, boiler flue economisers….

Okay, okay. How on earth do I know where to begin? Yes, it can be a bit overwhelming. Don’t forget you can call our advice and support line on 0808 808 2268 2268and speak to one of our experts, but read on for more information. Before you can work out what type to install you have to work out where you want to capture waste heat. If you have a small to medium scale commercial premises you probably want to look at options for your ventilation system and perhaps your boiler.

If your business is industrial, you’ll most likely have additional opportunities to capture heat from any number of processes. You should get in touch with one of our low carbon heat experts on 0808 808 2268 2268and they can help you look at your processes in a lot more detail.

Well, let’s start with something smaller than a factory. Good idea. If we take boilers, there’s only one option – boiler flue economisers. They capture waste heat and use it to pre-heat water before it’s fed to the boiler. If you have medium to large premises with a large boiler you’ll get bigger gains in efficiency. On the other hand, if you have a small property with a new efficient condensing boiler, it may not be worth it.

And what kind of costs/savings can we expect? Costs are in the region of £6,000-£8,000 and you can expect to see payback in four to five years. As well as improving efficiency by between 5%-15%, it increases the lifetime of the boiler. 

Okay, so far so good. What about heat recovery for ventilation systems? These are known as heat recovery ventilation systems, or HRVS’s. They work by capturing heat from air that’s leaving a building and using it to heat cooler incoming air. It ensures good circulation of fresh air, but unlike opening a window in the middle of winter you won’t be treated to an icy blast. This is where you get to choose between one of the various types we mentioned previously.

The thermal wheels, heat pipes and whatnot? How would I make that choice? It all comes down to balancing wants and needs. You need to consider the size of your premises, costs, efficiency savings and maintenance requirements.As a rule of thumb,higher efficiency heat recovery ventilation systems are larger and more expensive. A thermal wheel is the most efficient – on average you can expect 65%-75% efficiency gains. They’re not cheap but you can achieve great payback times – as little as two years in some cases. You need space for it so it may not suit small premises.

The simplest and cheapest one is the heat plate exchanger. It requires less space but efficiencies are still good – around 55%-65% – although the payback time tends to be slightly longer. Then there are heat pipe systems, which have similar efficiencies to the heat plate exchanger but the lowest maintenance requirements. Another option, if your incoming and outgoing air streams aren’t close together, is a coil/closed loop system. You can see around a 45%-50% efficiency improvement with these.

These efficiencies are impressive. Sounds like everyone should get one. Yes, in an ideal world. Although they may only be worth it unless your property is fully insulated with all air gaps plugged.

What about costs and savings? These are hugely variable due to the different types and sizes. As a ballpark figure, a standard office system might set you back £7,000-12,000. If the system has efficiencies of 70% it could save up to 40% on your gas bills.

Any other benefits? Yes, you get better air quality as it’s constantly getting refreshed. So less pollutants and allergens as well as moisture and condensation.

What about maintenance? Again this is hugely variable. Generally, the simpler cheaper ones are slightly less efficient and require slightly less maintenance, and vice versa. With all of them, you’ll need to check things like filters, clean the surfaces of heat exchangers, replace any broken seals, unblock condensate drains, that kind of thing.

Way back you mentioned heat recovery systems for industry. Yes, there’s huge potential for cost savings here, as well as preventing tons of carbon from being coughed out into the atmosphere. You can recover heat from any process that involves heating or cooling – for example, distilling, pasteurisation, refrigeration, dying and finishing, laundry drying and ovens to name a few. There’s also potential for the recovered heat to be used in district heating schemes which can help local communities and alleviate fuel poverty.

That sounds like a righteous thing to do. Doesn’t it? A perfect example of a win-win, closed loop energy system.

If you want to find out more about heat recovery systems and which one is right for your business, please give us a call at 0808 808 2268 or email us.