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Best practice with waste heat
Martyn Bridges, director of technical services at Worcester Bosch, discusses the various ways we can make more productive use of our wasted heat
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ecause of the rising costs of energy, inflation rates and the general squeeze on money, recovering as much heat and using as little
energy as possible is very topical, both in the last year
and for the foreseeable future. Even without these pressures, it is obviously sensible to recover as much heat as possible to be utilised elsewhere with the ambition of being more resourceful and wasting less.
HEATING SYSTEMS A history of heat waste
To some extent, in domestic heating at least, this activity started around 10 years ago, with the introduction of the flue gas heat recovery system. There was much scepticism about the device, which essentially sat in the flue ways of the boiler using the energy in the flue gases that was about to be expelled into the outside air. The heat it was extracting was normally channelled into the incoming mains water supply and pre-heated this supply for whenever hot water was needed, thus reducing the amount of gas required to heat the water. You were using heat which otherwise was just going to be expelled outside. This has since developed with wastewater heat
recovery also gaining popularity, especially in new- build properties. This is again a heat exchanger of sorts, that sits in the outlet of the wastewater system of the bath or the shower. This is water which has been used already and would normally be sent down to the wastewater system and ultimately into the drainage. The wastewater heat recovery system extracts as much heat from otherwise wasted water and adds this generally into the cold-water mains again, preheating the mains to a level where less gas, oil or electricity is required to reach a usable temperature.
A competitive market
Obviously, using such appliances have benefits, though they can be quite difficult to retrofit into existing properties, particularly the wastewater heat recovery system. However, they make complete sense ecologically and economically when being installed into new bathrooms or properties. Indeed, the flue gas heat recovery system is one of
“The wastewater heat recovery system extracts as much heat from otherwise wasted water and adds this generally into the cold-water mains again, preheating the mains to a level where less gas, oil or electricity is required to reach a usable temperature.”
the four additional measures that you must consider under the Boiler Plus considerations, introduced in April 2018. It is fair to say that it is not one of the more popular of the measures, that honour belongs to the load compensating thermostat. Of course if both are installed on a system, they are somewhat fighting against each other, as if the latter is working as designed, it will be lowering the temperature of the boiler, and subsequently the temperature of the flue gases escaping. In certain cases, this even makes the flue recovery system redundant. Notwithstanding this, recovering heat
through either methodology is a very sensible and easy way of saving energy.
With energy costs, inflation and the cost-of- living crisis affecting all in both the consumer and commercial space, being resourceful and wasting less has never been more important. On one hand it has the potential to reduce bills for homeowners by getting the most heat out of your system while from a commercial perspective, you are operating more efficiently. There is room for innovation in the waste heat space and it has the potential to be a large contributor to the reduction in carbon emissions and being more resourceful in how we heat our homes.
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