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Air Source Heat Pump FAQs
Based on many years experience we have compiled a very comprehensive list of questions that we are often asked. If you cannot find an answer to your question please don't hesitate to contact us by phone or email. Q. Are Air Source Heat Pumps Noisy? No, please watch the video to find out more. Quality installations of air source heat pumps should not be noisy, the noise impact on the property depends on the heat pump model and how well it is installed. Consideration should be given to the choice of anti-vibration and low noise components used. Q. Are heat pumps expensive to run? Not normally, please watch the video to find out more. The running costs of a heat pump depends heavily on how well the system (including the emitters) has been designed. Systems can be retrofitted into existing properties but great care needs to be taken by the installer to ensure that the system runs efficiently. You may need to upgrade part or all of the radiator system. Q. Will my house be cold with a heat pump? Absolutely not, please watch the video to find out more. The performance of a heat pump depends heavily on the design stage. A well designed heat pump with the correct emitters (radiators or underfloor heating) will heat the property perfectly and more comfortably than a conventional boiler. Find out about our warm home guarantee. Q. Are there any grants available? The Low Carbon Building Program grants were closed to new applicants on the 24th May 2010. This grant scheme was replaced with the Renewable Heat Premium (RHP) which paid £1300 in certain circumstances. The RHP has now been replaced with the Renewable Heat Incentive (RHI). Grants may also be available from your local council, you should contact them for further information. Q. Will I be eligible for the new Renewable Heat Incentive (RHI)? The RHI promises to pay more than 6.9p/kWh (12.5p/kWh for ground source) for every kWh the heat pump is predicted to output (proposed for 2014). IES are approved MCS installers so our installations are eligible. This equates roughly to an annual payment of £1250 for a typical domestic property. Q. Do I need underfloor heating for a heat pump to work properly? Underfloor heating operates at a lower flow temperature than some other forms of heating, such as radiators. All heat pumps operate at a higher efficiency when used with a lower flow temperature distribution system. Some heat pumps can only be efficiently used with underfloor heating. We use heat pumps that operate efficiently at low and high flow temperatures. Q. Can a heat pump work with radiators? Our heat pumps can achieve high flow temperatures in excess of 55 degrees. This means that our heat pumps can be used with both radiators and underfloor heating. Q. Do I need to increase the size of my radiators? Most installed radiators have been naturally oversized, this means that often a retrofit of a heat pump into an existing property doesn’t need any modifications to be made to the existing radiators. This is especially when insulation levels have been upgraded after the heating circuit was fitted, ie subsequent filling of cavity walls. You should ask your consultant about your specific circumstances. Q. My existing boiler has a much larger power capacity that what you have advised for a heat pump, will it do the job? Most conventional boilers are massively oversized because extra boiler capacity costs very little. To be cost effective it is much more important that a heat pump is sized properly. We will calculate the actual heat input required for your home and not base the size of the heat pump on your current boiler capacity. Q. How much will I save on my fuel bills? Studies have shown that switching from mains gas will save approximately 25% of your heating costs. Switching from oil or LPG could save more than 50%. Over sizing radiators or using underfloor heating can often reduce running costs for heat pumps. Q. Do air source heat pumps work in winter? Yes, our air source heat pumps will give high outputs down to -20 degrees external temperature. Q. Does the heat pump need a back up? Our system can give the rated output down to -20degrees external temperature, therefore a back up system is not required. Q. Am I at risk of legionella related illness with a heat pump? Legionella bacteria cannot survive at temperatures over 60 degrees. Our normal control systems and immersion heater will raise the temperature of the hot water cylinder to over 60 degrees periodically to pasteurise the tank. To save electricity we time this so that the immersion heater only needs to raise the tank the final 5 degrees (from 55 to 60 degrees). Q. Will the heat pump need a refrigeration engineer for servicing? Some heat pumps have refrigeration pipes running between the indoor and outdoor units. This type of pipework and system legally needs to be serviced annually. We typically use monoblock heat pumps that do not have any external refrigeration pipework. This means the service requirement is more akin to a conventional refrigerator, i.e. very little. Q. How often will the system need to be serviced? Our air source heat pumps need an annual inspection up to 3 years in age to maintain the 3 year warranty. Q. Does a heat pump need planning permission? The government plans to make air source heat pumps permitted development in the future. This means they will not need planning permission and a home owner that is not in a conservation area or a listed building will be able to proceed without permission. However, currently air source heat pumps do technically require planning permission and we can assist you with this process. Q. Do I need a three phase electricity supply? Generally speaking, properties larger than a 6 bed detached home may require a 3 phase electricity supply. Q. Can the heat pump heat our hot water cylinder? Yes, our heat pumps can achieve flow temperature in excess of 55 degrees. Domestic hot water at your taps needs to be at around 40 degrees. Q. How long will an installation take? Air source heat pump installations may take 2-4 days. Q. How big is the heat pump? Our heat pumps have indoor units that primarily contain the water cylinder so occupy similar space to a fridge freezer. The outdoor unit is similar to a typical air conditioning unit. Q. Can an air source heat pump be fitted indoors? Our air source heat pumps need a good flow of fresh air so therefore need to be fitted outside. Q. What is a heat pump and how does a heat pump work? The heat pump uses a refrigeration cycle to move heat from one place to another. The process also upgrades the low grade heat from outside to much higher temperatures in your home. It works like a fridge but in reverse. Q. How can the efficiency be greater than 100%? To calculate the system efficiency we divide the amount of heat output by the amount of electricity that the system runs on and multiply the result by 100. So if the system generates 4kwh of heat and uses 1kWh of electricity the system efficiency is 400% (COP of 4). The reason the efficiency is greater than 100% is because we do not include the heat from outside in the equation, we consider this as completely free, which it is. Q. What is a Coefficient of Performance (COP)? The COP is the same as the system efficiency. A COP of 4 is the same as a system efficiency of 400%. Q. Does your price include connection to my existing/new heating system? Yes, we include the connection to your existing heating system unless there is a specific reason for us not to. We are often surprised by how many of our competitors want to install a heat pump but not connect it to your heating system. They expect the customer to employ another contractor to complete this, the potentially more difficult part, of the installation. We will normally leave your property with your heating system running with no other trades people to employ. Q. Does your price include the required electric works? Yes, we include the required electrical works in your property unless there is a specific reason for us not to. We are often surprised by how many of our competitors want to install a heat pump but connect the power to the unit. They expect the customer to employ another contractor to complete this. We will normally leave your property with your heating system running with no other trades people to employ. Q. Does a limited range of compatible hot water cylinders mean that I cannot have solar panels and a heat pump? No, unlike our competitors we do not usually use a 'packaged' hot water cylinder. Packaged cylinders are the default offerings from manufacturers which attempt to 'pigeon hole' customers into a very limited number of groups. This often means that there are no solar thermal option available. IES have cylinders made to our specification. This enables to us to fit solar panels with heat pumps. We also can supply a solar compatible cylinder for a possible future upgrade. Q. Do I need a buffer vessel with an air source heat pump? This depends on the specification of the heat pump, inverter driven heat pumps usually do not require buffer vessels as they are able to modify their heat output to closely match the heat demand of the building. Heat pumps without inverters consume more electricity to start up so therefore will use less electricity if the number of startups can be minimised. A large tank of heating water in the distribution system (ie the buffer tank) enables the heat pump to run for longer with less startups. IES usually fit air source heat pumps with inverter control and hence do not normally require a buffer tank. Q. Do I need to change my hot water cylinder with a new heat pump installation? Given that the heat pump operates at a lower water flow temperature than a conventional boiler we would normally recommend that the hot water cylinder is upgraded to maximize the efficiency of the heat pump. However, in circumstances where the hot water demand from the heat pump is low we may be able to utilise the existing cylinder. This would include hot water cylinders that have third party heat sources such as a solar thermal system or an IES ImmerSun (solar PV boosted hot water). Very large cylinders may also be accommodated by the integration of a high efficiency external plate heat exchanger. Please note that these answers are designed to be appropriate for typical installations. The exact specification for your system will be detailed in your personal proposal.

Air Source Heat Pump FAQs

Based on many years experience we have compiled a very comprehensive list of questions that we are often asked. If you cannot find an answer to your question please don't hesitate to contact us by phone or email.

Q. Are Air Source Heat Pumps Noisy?

No, please watch the video to find out more. Quality installations of air source heat pumps should not be noisy, the noise impact on the property depends on the heat pump model and how well it is installed. Consideration should be given to the choice of anti-vibration and low noise components used.

Q. Are heat pumps expensive to run?

Not normally, please watch the video to find out more. The running costs of a heat pump depends heavily on how well the system (including the emitters) has been designed. Systems can be retrofitted into existing properties but great care needs to be taken by the installer to ensure that the system runs efficiently. You may need to upgrade part or all of the radiator system.

Q. Will my house be cold with a heat pump?

Absolutely not, please watch the video to find out more. The performance of a heat pump depends heavily on the design stage. A well designed heat pump with the correct emitters (radiators or underfloor heating) will heat the property perfectly and more comfortably than a conventional boiler.
Find out about our warm home guarantee.

Q. Are there any grants available?

The Low Carbon Building Program grants were closed to new applicants on the 24th May 2010. This grant scheme was replaced with the Renewable Heat Premium (RHP) which paid £1300 in certain circumstances. The RHP has now been replaced with the Renewable Heat Incentive (RHI). Grants may also be available from your local council, you should contact them for further information.

Q. Will I be eligible for the new Renewable Heat Incentive (RHI)?

The RHI promises to pay more than 6.9p/kWh (12.5p/kWh for ground source) for every kWh the heat pump is predicted to output (proposed for 2014). IES are approved MCS installers so our installations are eligible. This equates roughly to an annual payment of £1250 for a typical domestic property.

Q. Do I need underfloor heating for a heat pump to work properly?

Underfloor heating operates at a lower flow temperature than some other forms of heating, such as radiators. All heat pumps operate at a higher efficiency when used with a lower flow temperature distribution system. Some heat pumps can only be efficiently used with underfloor heating. We use heat pumps that operate efficiently at low and high flow temperatures.

Q. Can a heat pump work with radiators?

Our heat pumps can achieve high flow temperatures in excess of 55 degrees. This means that our heat pumps can be used with both radiators and underfloor heating.

Q. Do I need to increase the size of my radiators?

Most installed radiators have been naturally oversized, this means that often a retrofit of a heat pump into an existing property doesn’t need any modifications to be made to the existing radiators. This is especially when insulation levels have been upgraded after the heating circuit was fitted, ie subsequent filling of cavity walls. You should ask your consultant about your specific circumstances.

Q. My existing boiler has a much larger power capacity that what you have advised for a heat pump, will it do the job?

Most conventional boilers are massively oversized because extra boiler capacity costs very little. To be cost effective it is much more important that a heat pump is sized properly. We will calculate the actual heat input required for your home and not base the size of the heat pump on your current boiler capacity.

Q. How much will I save on my fuel bills?

Studies have shown that switching from mains gas will save approximately 25% of your heating costs. Switching from oil or LPG could save more than 50%. Over sizing radiators or using underfloor heating can often reduce running costs for heat pumps.

Q. Do air source heat pumps work in winter?

Yes, our air source heat pumps will give high outputs down to -20 degrees external temperature.

Q. Does the heat pump need a back up?

Our system can give the rated output down to -20degrees external temperature, therefore a back up system is not required.

Q. Am I at risk of legionella related illness with a heat pump?

Legionella bacteria cannot survive at temperatures over 60 degrees. Our normal control systems and immersion heater will raise the temperature of the hot water cylinder to over 60 degrees periodically to pasteurise the tank. To save electricity we time this so that the immersion heater only needs to raise the tank the final 5 degrees (from 55 to 60 degrees).

Q. Will the heat pump need a refrigeration engineer for servicing?

Some heat pumps have refrigeration pipes running between the indoor and outdoor units. This type of pipework and system legally needs to be serviced annually. We typically use monoblock heat pumps that do not have any external refrigeration pipework. This means the service requirement is more akin to a conventional refrigerator, i.e. very little.

Q. How often will the system need to be serviced?

Our air source heat pumps need an annual inspection up to 3 years in age to maintain the 3 year warranty.

Q. Does a heat pump need planning permission?

The government plans to make air source heat pumps permitted development in the future. This means they will not need planning permission and a home owner that is not in a conservation area or a listed building will be able to proceed without permission. However, currently air source heat pumps do technically require planning permission and we can assist you with this process.

Q. Do I need a three phase electricity supply?

Generally speaking, properties larger than a 6 bed detached home may require a 3 phase electricity supply.

Q. Can the heat pump heat our hot water cylinder?

Yes, our heat pumps can achieve flow temperature in excess of 55 degrees. Domestic hot water at your taps needs to be at around 40 degrees.

Q. How long will an installation take?

Air source heat pump installations may take 2-4 days.

Q. How big is the heat pump?

Our heat pumps have indoor units that primarily contain the water cylinder so occupy similar space to a fridge freezer. The outdoor unit is similar to a typical air conditioning unit.

Q. Can an air source heat pump be fitted indoors?

Our air source heat pumps need a good flow of fresh air so therefore need to be fitted outside.

Q. What is a heat pump and how does a heat pump work?

The heat pump uses a refrigeration cycle to move heat from one place to another. The process also upgrades the low grade heat from outside to much higher temperatures in your home. It works like a fridge but in reverse.

Q. How can the efficiency be greater than 100%?

To calculate the system efficiency we divide the amount of heat output by the amount of electricity that the system runs on and multiply the result by 100. So if the system generates 4kwh of heat and uses 1kWh of electricity the system efficiency is 400% (COP of 4). The reason the efficiency is greater than 100% is because we do not include the heat from outside in the equation, we consider this as completely free, which it is.

Q. What is a Coefficient of Performance (COP)?

The COP is the same as the system efficiency. A COP of 4 is the same as a system efficiency of 400%.

Q. Does your price include connection to my existing/new heating system?

Yes, we include the connection to your existing heating system unless there is a specific reason for us not to. We are often surprised by how many of our competitors want to install a heat pump but not connect it to your heating system. They expect the customer to employ another contractor to complete this, the potentially more difficult part, of the installation. We will normally leave your property with your heating system running with no other trades people to employ.

Q. Does your price include the required electric works?

Yes, we include the required electrical works in your property unless there is a specific reason for us not to. We are often surprised by how many of our competitors want to install a heat pump but connect the power to the unit. They expect the customer to employ another contractor to complete this. We will normally leave your property with your heating system running with no other trades people to employ.

Q. Does a limited range of compatible hot water cylinders mean that I cannot have solar panels and a heat pump?

No, unlike our competitors we do not usually use a 'packaged' hot water cylinder. Packaged cylinders are the default offerings from manufacturers which attempt to 'pigeon hole' customers into a very limited number of groups. This often means that there are no solar thermal option available. IES have cylinders made to our specification. This enables to us to fit solar panels with heat pumps. We also can supply a solar compatible cylinder for a possible future upgrade.

Q. Do I need a buffer vessel with an air source heat pump?

This depends on the specification of the heat pump, inverter driven heat pumps usually do not require buffer vessels as they are able to modify their heat output to closely match the heat demand of the building. Heat pumps without inverters consume more electricity to start up so therefore will use less electricity if the number of startups can be minimised. A large tank of heating water in the distribution system (ie the buffer tank) enables the heat pump to run for longer with less startups. IES usually fit air source heat pumps with inverter control and hence do not normally require a buffer tank.

Q. Do I need to change my hot water cylinder with a new heat pump installation?

Given that the heat pump operates at a lower water flow temperature than a conventional boiler we would normally recommend that the hot water cylinder is upgraded to maximize the efficiency of the heat pump. However, in circumstances where the hot water demand from the heat pump is low we may be able to utilise the existing cylinder. This would include hot water cylinders that have third party heat sources such as a solar thermal system or an IES ImmerSun (solar PV boosted hot water). Very large cylinders may also be accommodated by the integration of a high efficiency external plate heat exchanger.

Please note that these answers are designed to be appropriate for typical installations. The exact specification for your system will be detailed in your personal proposal.

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