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FAQ Page

How does Air Conditioning work?

Air conditioning is about transferring heat from one place to another. This is undertaken via refrigerant within the system which by changing state from liquid to gas, and vice versa, absorbs and discharges heat as required.

For example if a room is too hot, the indoor unit will draw in room air; pass this over a coil to transfer the heat from the air to refrigerant within the system. The air, minus the heat, is then returned to the room providing ‘cooling’. Meanwhile the refrigerant that has absorbed the heat travels to the outdoor part of the system where the refrigerant changes state again and rejects the heat to be either discarded or reused elsewhere. The refrigerant then continues around the circuit again to repeat the process.

What is a Heat Pump?

For example if a room is too cold, the outdoor section of the system will absorb heat from external ambient air into the refrigerant and the ‘hot’ refrigerant will travel via pipework to the indoor part of the system. Again the indoor unit will then draw in room air, but this time the heat will be transferred to the air from the refrigerant. The air will then be returned to the room providing ‘heating’.

It should be noted that a lot of heat pumps are able to absorb heat even when external temperatures are as low as -15oC

Why is Heat Pump Air Conditioning so energy efficient?

A heat pump system absorbs “free” heat from external air (or other sources) and can provide up to 4kw of heating for 1 kw of power input.

Please note that this is at normal operation and therefore we must advise that during extreme conditions i.e. very cold days during winter the system will work harder and draw more power to achieve the same output and therefore the ratio may drop. However, conversely on warmer winter days the output may also rise above 4 kW.

Therefore as our extreme days are generally less than the number of average or higher temperature days this is still more efficient when compared to gas heating at 0.95 kW output to 1 kW of power input and electrical heating at 1 kW output to 1 kWatt power input. As mentioned above, a lot of heat pumps still absorb heat even when external temperatures are as low as -15oC.

Can Heat Pumps supply hot water?

Yes, using the same process as above, but by transferring the heat into water instead of air, hot water can be supplied for sinks and showers as well as for radiator and/or underfloor heating purposes.

How often will filters need to be cleaned?

All manufacturers’ recommend that filters are cleaned or at least checked once a month, however this will depend on the application and level of usage. For example, a home without pets may only require the filters to be cleaned every 3 months, whereas a home with pets, and lots of coming and going, may find that they need to clean filters more frequently.

However with commercial and industrial installations this will vary widely according to the type of business, for example an office will not require filters to be cleaned as much as a shop with a high volume of traffic and doors to outside, opening and closing, whereas a hairdresser with lots of air-borne particles will require a high level of cleaning and possibly special filtration.

How often will the system need to be serviced?

All manufacturers’ recommend that systems be serviced ‘regularly’ which again will depend on the application and usage as mentioned above. However with domestic heat pumps we would suggest that the systems at least be serviced on ‘changeover’ from cooling to heating and possibly vice-versa. With high usage systems, particularly commercial and industrial we would recommend 3 or 4 service visits per year, but any servicing would need to be specifically tailored to the application. We would be pleased to discuss your requirements without obligation.

Will Heat Pump Air Conditioning reduce my heating bills?

When compared to other usual forms of heating a reduction will be noticeable; as mentioned heat pumps can provide around 4 kW of heating for every 1 kW of power input, whereas gas heating generally operates at 0.95 kW output to 1 kW of power input and electrical heating at 1 kW output to 1 kWatt power input. However it should be noted that when using the system for cooling in summer there will be an implication as the system will be running when neither gas or electric heating is normally used.

What are COP and EER?

  • COP is Co-efficient Of Performance & is the ratio for energy efficiency for heating
  • EER is Energy Efficiency Ratio & is the ratio for energy efficiency for cooling

The figures given for these essentially provide the same information which is the ratio of output (or conditioned air) kWatt output to every 1 kWatt input. For example:

  • An EER of 3.5 kWatt cooling output for every 1 kWatt of electrical input.
  • A COPof 4.0 kWatt heating output for every 1 kWatt of electrical input.

What is the procedure and how long will the installation take?

There are various systems available where a single outdoor unit can be connected to several indoor units but for this purpose we have based the answer to this question on a single split system, i.e. one outdoor unit connected to one indoor unit.

  • Outdoor unit to be placed in position either on brackets on a wall or at ground or roof level.
  • Indoor unit supportwork to be placed in position
  • Holes to be drilled to allow pipework to be routed between the units.
  • Suitably insulated refrigerant quality interconnecting pipework, generally comprising 2 pipes, to be run between the outdoor and indoor units (please note that this must be refrigerant quality pipework to cope with high pressure refrigerant, plumbers copper would be dangerous).
  • Interconnecting cabling to be run between the indoor and outdoor positions.
  • Indoor unit to be fixed into position with a drain line run to ensure effective discharge of condensate, a pump may be required.
  • Outdoor and indoor units to be connected electrically and mechanically to the pipework and cabling.
  • Controller to be located in a convenient position adjacent to the indoor unit with control cabling run as necessary back to the indoor unit.
  • Interconnecting pipework to be pressure tested to ensure pipework integrity.
  • System to be evacuated and dehydrated and a vacuum created within the system to ensure it contains no moisture and/or non-condensables which could either damage the system or seriously affect its operation.
  • Following successful evacuation and dehydration, a specific / critical amount of refrigerant is to be charged into the system.
  • System to be run, tested in all modes (cooling, heating, dehumidification and fan only) and commissioned.
  • Our engineer will then run through the controls and system operation with the end user.

The length of time taken to install will depend on where the units are located in relation to each other and the pipe route, but generally a small split system (one indoor and one outdoor unit) will take between 1 and 2 days to install.

What is a VRF / VRV System?

VRF stands for Variable Refrigerant Flow / VRV stands for Variable Refrigerant Volume (same thing different wording) and these systems provide very energy efficient heating or cooling.

As the name suggests a VRF / VRV system varies refrigerant according to the specific capacity required from the indoor units for optimum use of the refrigerant and therefore optimum and efficient energy usage.

A VRF / VRV system involves a single large outdoor unit connected to several indoor units;

  • A heat pump VRF / VRV system will require that all the indoor units are either cooling or heating
  • A heat recovery VRF / VRV system can provide simultaneous heating and cooling, i.e. some indoor units can be cooling whilst others are heating.

Although the heat pump VRF / VRV system is very energy efficient the heat recovery VRF / VRV system takes this energy efficiency even further by transferring heat across the system; for example on a building with orientation for sun on one side only in the morning rotating to the other side for sun in the afternoon, heat rejected from units on the ‘sunny side’ can be recovered to the units on the shaded side to provide ‘free’ heat.

The energy efficiency can be even further improved by including a heat pump boiler within the system so that any rejected heat can be recovered into the hot water system to reduce conventional boiler running costs.

The above is a very brief guide to these systems, and we would be pleased to discuss any aspect further without obligation.

What are air to air and air to water systems?

Air to air is when heat is recovered from air, either ambient or indoor, and transferred to another connected unit where the heat is also discharged by air.

Air to water, is where heat is recovered from air and transferred to another unit where the heat is discharged into water. This can either be heat from ambient air transferred to an underfloor and/or radiator water heating loop or hot water system or conversely heat can be recovered from indoor air and transferred to another unit to be rejected or reused.

What is Ground Source Heat Pump Air Conditioning?

This technology combines heat pump technology (see ‘What is a Heat Pump?’) with renewable energy stored in the ground to provide one of the most energy efficient forms of heating and cooling buildings.

This involves either a borehole or shallow trenches, or in some cases heat extraction from a localised pond or lake. Pipes in a closed water loop extract this stored energy which is then used to provide a building with heating or hot water which provides exception energy efficiency when further combined with the heat recovery properties of heat pump technology.

What is a Heat Pump Boiler?

Generally the heat pump boiler is a heat pump that will recover heat and discharge it into water for either underfloor heating, low temperature radiator/fan coil heating or hot water purposes. See also ‘What are ‘air to air’ and ‘air to water’ systems?’ and ‘What is a Heat Pump?’.

How can Heat Recovery Ventilation Units improve energy efficiency even more?

These HRV units provide fresh air and also extract ‘stale’ air, however heat is recovered between the fresh air and exhausted air, without mixing, to pre-heat or pre-cool incoming air. This means that ‘paid for’ heating or cooling is not extracted with the exhaust air and that further energy is not required to heat and cool the incoming air. These units will also recover / reject heat from / to ambient air to provide ‘free’ heating or cooling.

These units can either work independently or be linked into air conditioning controls so that they work in tandum with each other; for example if there is sufficient heating or cooling from ambient air the AC controls will detect this and adjust the cooling or heating output accordingly.

After reading the frequently asked questions and there is something that is still unclear please feel free to contact Airtemp using the contact us button at the top.

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