<\/span><\/h2>\nHeat pump environment<\/h3>\n
The heat pump environment<\/strong> includes every condition that influences the heat pump. It covers the building, climate, heat source, heat distribution system, electrical supply, installation area, users and regulatory setting. These elements form one connected energy system.<\/p>\nThe environment includes:<\/p>\n
\n- Outdoor and ground temperatures<\/li>\n
- Groundwater conditions<\/li>\n
- Building heat loss<\/li>\n
- Required indoor temperatures<\/li>\n
- Radiators, underfloor heating or fan coils<\/li>\n
- Heating-water flow and return temperatures<\/li>\n
- Domestic hot water demand<\/li>\n
- Cooling demand<\/li>\n
- Electrical connection capacity<\/li>\n
- Sound-sensitive neighbouring properties<\/li>\n
- Refrigerant safety requirements<\/li>\n
- Building, water and environmental permissions<\/li>\n
- Control and communication systems<\/li>\n<\/ul>\n
Operating boundary<\/h3>\n
An operating boundary<\/strong> is a limit that must not be exceeded during operation. It may define a minimum source temperature, maximum flow temperature, permissible compressor speed or minimum water flow. The manufacturer normally specifies these values in the technical documentation.<\/p>\nOperating boundaries protect:<\/p>\n
\n- Compressor reliability<\/li>\n
- Refrigerant pressure limits<\/li>\n
- Heat exchanger integrity<\/li>\n
- Electrical components<\/li>\n
- Water circuits<\/li>\n
- Occupants and service personnel<\/li>\n<\/ul>\n
Operating envelope<\/h3>\n
The operating envelope<\/strong> is the complete range of valid operating conditions. It is normally expressed as combinations of source temperature, heat-sink temperature and compressor operating state. A heat pump may be permitted to operate at one condition but restricted at another.<\/p>\nFor example, a model may deliver a high flow temperature when the outdoor air is mild. The same temperature may not be available at the lowest design outdoor temperature. Product selection must therefore use a performance map rather than one maximum value.<\/p>\n
Boundary condition<\/h3>\n
A boundary condition<\/strong> is a defined input used for calculation, testing or system design. Examples include an outdoor temperature of \u221210\u00b0C, an indoor design temperature of 21\u00b0C and a heating-water flow temperature of 45\u00b0C. Changing one boundary condition changes the calculated result.<\/p>\nCommon boundary conditions include:<\/p>\n
\n- Design outdoor temperature<\/li>\n
- Design indoor temperature<\/li>\n
- Source inlet temperature<\/li>\n
- Flow and return temperature<\/li>\n
- Required heating capacity<\/li>\n
- Domestic hot water temperature<\/li>\n
- Ground or water availability<\/li>\n
- Electricity tariff<\/li>\n
- Permitted sound level<\/li>\n
- Expected operating hours<\/li>\n<\/ul>\n
Hard and soft boundaries<\/h3>\n
A hard boundary<\/strong> is a limit that must not be crossed. It may be imposed by the manufacturer, a safety standard, a permit or legislation. Operation beyond a hard boundary can cause a shutdown, safety risk, damage or legal non-compliance.<\/p>\nA soft boundary<\/strong> allows operation but may produce an undesirable result. The heat pump may continue running, but efficiency, comfort, sound or cost may become unacceptable. Soft boundaries often determine whether a technically possible project is also commercially sensible.<\/p>\nExamples include:<\/p>\n
\n- Hard boundary:<\/strong> Maximum permitted refrigerant pressure.<\/li>\n
- Hard boundary:<\/strong> Prohibited installation position for a flammable refrigerant.<\/li>\n
- Hard boundary:<\/strong> Minimum required water flow through the condenser.<\/li>\n
- Soft boundary:<\/strong> High flow temperature that significantly reduces efficiency.<\/li>\n
- Soft boundary:<\/strong> Night operation that is legal but still noticeable to occupants.<\/li>\n
- Soft boundary:<\/strong> Frequent use of an electric backup heater.<\/li>\n<\/ul>\n
Product boundary and system boundary<\/h3>\n
The product boundary<\/strong> covers the heat pump unit and its declared characteristics. The system boundary<\/strong> includes the complete heating, cooling and domestic hot water installation. A product can meet its declared performance while the installed system performs poorly.<\/p>\nThe wider system boundary includes:<\/p>\n