Air to Water Heat Pumps for Domestic Use

Air source heat pumps absorb heat from the outside air. This heat can then be used to heat radiators, underfloor heating systems, or warm air convectors and hot water in your home.

An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can get heat from the air even when the temperature is as low as -15° C. Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat through heat exchangers to the heating and hot water circuits of the house.

Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.

 

Benefits of Heat pumps

·         Lower fuel bills if certain circumstances, especially if you are replacing conventional electric heating

·         potential income through the UK government’s Renewable Heat Incentive (RHI)

·         Capable of reducing running costs and CO2 emissions

·         no fuel deliveries needed

·         can heat your home as well as your water

·         minimal maintenance required

  • Helps achieve renewable energy targets
  • Easy to design, install and maintain
  • Fully scalable and can work independently or in conjunction with other systems

For every 1kW of electricity fed into a heat pump unit, you could get at least 3kW of heating energy. The overall system efficiency and energy savings will depend on the comparison with your current heating system, satisfactory system design and installation, and operational settings and how the system is set up and used

Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. During the winter they may need to be on constantly to heat your home efficiently. You will also notice that radiators won't feel as hot to the touch as they might do when you are using a gas or oil boiler.

 

Type of Air to Water Heat pumps

 

Mono Block

This system consists of outdoor heat pumps, which connects directly via water pipework to the internal hot water tank. From the tank water is then distributed to the hot water and heating circuits as per any conventional system.

 

 
   
  • Split Type

This system combines an outdoor Heat pump which is connected via refrigerant pipework to the heat exchanger located internally; this then connects to a Hot water tank in the same way.

 

How do I decide if I need a Mono Block or Split type?

1)    Capacity, Split type is available in larger sizes due to the heat exchangers been separate.

2)    If you use a mono bloc you need to run water pipework from inside to outside and to ensure the water within the system does not freeze. As there is a risk of damage if this happens. With a split type there is only refrigerant in the system and all water is contained in the internal heat exchanger, reducing the risk of freezing

3)     Mono Bloc are more common as they are easier to install and your local trained plumber can do this rather than requiring the services of an F Gas qualified refrigeration engineer to install the refrigeration pipework associated with a split type system

4)    Mono bloc systems take up more room externally.

Note:

It is legal requirement that anyone working on a Heat pump refrigeration circuit must have F Gas Certification.

 

Is an Air to Water Heat pump Suitable?

To tell if an air source heat pump is right for you, there are a few key questions to consider:

  • Do you have somewhere to put it? 
  • You'll need a place outside your home where a unit can be fitted to a wall or placed on the ground. It will need plenty of space around it to get a good flow of air. A sunny wall is ideal.
  • Is your home well insulated? 
  • Since air source heat pumps work best when producing heat at a lower temperature than traditional boilers, it's essential that your home is insulated and draught-proofed well for the heating system to be effective.
  • What fuel will you be replacing? 
  • The system will pay for itself much more quickly if it's replacing an electricity or coal heating system. Heat pumps may not be the best option for homes using mains gas.
  • What type of heating system will you use? 
  • Air source heat pumps can perform better with underfloor heating systems or warm air heating than with radiator-based systems because of the lower water temperatures required.
  • Is the system intended for a new development?
  •  Combining the installation with other building work can reduce the cost of installing the system.

Costs

Installing a typical system costs around £6,000 to £12,000 dependant on the sizes of the property. Running costs will vary depending on a number of factors including the size of your home, how well insulated it is and what room temperatures you are aiming to achieve.

Savings

How much you can save will depend on what system you use now, as well as what you are replacing it with. Your savings will be affected by:

  • Your heat distribution system.
  •  If you have the opportunity, underfloor heating can be more efficient than radiators because the water doesn’t need to be so hot. If underfloor heating isn’t possible, use the largest radiators you can. Your installer should be able to advise on this.
  • Your fuel costs. 
  • You will still have to pay fuel bills with a heat pump because it is powered by electricity, but you will save on the fuel you are replacing.
  • Your old heating system. 
  • If your old heating system was inefficient, you are more likely to see lower running costs with a new heat pump.
  • Water heating.
  •  If the heat pump is providing hot water then this could limit the overall efficiency. You might want to consider solar heating to provide hot water in the summer and help keep your heat pump efficiency up.