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Pinterest | Chillmax Technologies
The function of a reversing valve that enables a heat pump to have both cooling and heating modes .
subsidised in many countries ( like solar geysers were a couple of years ago in the local context ). This incentive in these countries has put the heat pump ‘ in fashion ’ because of their proven results as a highly efficient way to decarbonise the cooling and heating sector – that is known to be energy intense , and therefore resource heavy . Heat pumps also partner well with decentralised green energy solutions such as solar PV . The efficiency of these units is related to the specified COP , however in this regard , test conditions must be considered .
Using existing external energy sources like brine , water , and air for heating , cooling , and heat recovery , makes heat pumps suitable in both new-builds and renovation projects to reduce energy consumption .
Heat pumps are further designated according to the media at the evaporator and condenser , so in an air-to-air heat pump for example , the heat is extracted from the surrounding air via the evaporator and passed ( in the form of a temperature increase ) via the heat pump cycle to the air of the space that is being heated . This is the principle that will generally be found in simple and inexpensive split air-conditioning units with a cyclereverse function .
In the case of an air to water heat pump , the heat is taken from the surrounding air , as with the air-to-air system , but on the secondary side it is released into the hot water or heating circuit . In the case of a water ( brine ) to water heat pump , the heat is generally extracted from the ground to be released into the hot water network . Water or brine can be used depending on the expected temperatures . Where pure water is used , special consideration must be given to possible operating conditions at sub-zero temperatures and during winter times . If in doubt , the addition of antifreeze ( glycol or some other alcohol ) may be required . Where a primary circuit runs at markedly sub-zero temperatures , brine is to be preferred .
Water ( brine ) heat pumps can be further subdivided into groundwater or well-water heat pumps and heat pumps with horizontal and vertical collectors . For a groundwater or wellwater heat pump the heat is taken from the groundwater or from a well .
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RACA Journal I October 2021 www . hvacronline . co . za