22
FEATURE
Heat Pumps have a role if
selected and installed correctly !
By
Rory Macnamara
The Heat Pump matrix gives an indication of the wide range available to the engineer and plumber and certainly does not include the entire range available . Due to space restraints ( yes , we are suffering as well ), we only used the matrixes supplied by advertisers .
Whilst this is not our normal policy as news is news and readers are entitled to know about what is happening , a matrix that purposely avoids mentioning companies and brands , rather focusing on the essential elements , deserves the support of companies who wish to identify with their product .
However , that is just by way of explanation and represents a wide selection available to the market .
Engineers have commented , rather unhappily , that the suppliers , stated generally , seem to have difficulty in accepting that the ambient temperature is at the point of installation for the heat pump to work effectively and efficiently and not necessarily in the laboratory situation . They argue that this accounts for the poor reputation that Heat Pumps have and unfairly so .
So , I looked for a relatively simple definition of ambient temperature that even a dumbo like myself could understand : “ Ambient temperature range refers to a scale of hotness or coldness in the immediate atmosphere environment as recorded in a universally accepted unit of measure such as Celsius , Fahrenheit or Kelvin . It is a vital parameter to observe to optimise equipment function .”
A Heat Pump is a device / equipment that pulls energy out of air for the purpose of either heating or cooling a space collectively known as space conditioning . Heat pumps operate as a heat engine in reverse , as they do work from an input of electricity to push heat from a cold place to a warm place . This may well violate the second law of thermodynamics , but the key reason it does not is because such heat transfer is not spontaneous – it requires an input of energy to do so .
So , for water , the heat pump water heaters use electricity to move heat from one place to another instead of generating heat directly . Therefore , they can be two to three times more energy efficient than conventional electric resistance water heaters . To move the heat , heat pumps work like a refrigerator or air-conditioner in reverse .
SANS 204 Energy Efficiency in Buildings and a host of other standards which all eventually link to SANS 10252-1 , states in Section 4.5.2.1 : “ A minimum of 50 % by volume of the annual average hot water hearting requirements shall be provided by means other than electrical resistance heating , but not limited to solar heating , heat pumps , heat recovery from other systems or processes .”
As shown , there are several applications for heat pumps across air and water , aircon , refrigeration , plumbing and swimming pools .
We list some of the SABS standards applicable where we could find them for different applications .
For plumbing , though , bear in mind the two main standards for design and installation – SANS 10252 1 & 2 and 10254 . These both refer , as normative references to SANS 151 , 204 , 5151,13253 , 1687 , 1352 .
In order , therefore , to achieve the saving of three times or more , the ambient temperature plays a critical part in achieving the savings .
A further essential is a Letter of Authority ( LOA ) which must be obtained from the National Regulator for Compulsory Specifications ( NRCS ).
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www . plumbingafrica . co . za @ plumbingonline @ plumbingonline @ PlumbingAfricaOnline September 2021 Volume 27 I Number 7