Heat Pumps

As we all become much more aware of our carbon footprint an increasing number of people are turning to an alternative way of heating their home. Rather than burning precious fossil fuels such as gas and oil there is a relatively new technology that is taking Britain by storm - heat pumps.

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How do heat pumps work?

Most home heating systems either burn fuel or convert electricity into heat. Heat pumps are different because they don’t actually generate heat. Instead they harness existing heat energy that is already present in the environment, such as from the air, the ground, the sun and groundwater, and moves it into your home through a unit called a heat exchanger. Because they capture heat, rather than burn fuel, they emit no carbon dioxide.

They do use electricity in the process, however the quantity of heat delivered into your home is much greater than the quantity of electricity used to power the heat pump system. If you’d like to see more detailed, technical information about how they work check out the Energy Saving Trust website.

How much does a heat pump cost?

The cost of installing a heat pump is currently more expensive than the traditional gas boiler but, like anything, as they become more popular then the cheaper they will become.

There are three things to consider when opting for a heat pump as a heating system for your home:

Installation Cost

  • The installation of the heat pump system only needs to be done once. When the pipework is in place, it’s only the heat pump units that need to be replaced in the future and they last for 20-25 years.
  • A heat pump system heats the home at a lower temperature than a traditional boiler, so you may need to invest in larger radiators or maybe consider underfloor heating.
  • Your home may also need additional insulation - heat pump systems are not very efficient in draughty, poorly insulated properties.
  • To go completely off-grid and avoid all heating bills, you may want to consider solar panels or a wind turbine to power your heat pump. This is purely an optional extra and would obviously increase the installation cost considerably.
  • As with gas boilers you will need to use an appropriately registered or accredited installer to install such a system and you should obtain a comprehensive quote before going ahead.
  • The typical cost to install an air-source heat pump in a 4 bedroom house is around £10-13k but this is very general, depends on a lot of factors and will continue to come down as more pumps are fitted.

Running Costs

  • The only running cost for a heat pump is the electricity used to run the pump. Because the unit has to be located outside you could find that more electricity is used when the outdoor temperature drops during the winter months.
  • However, compared to your boiler, which could operate at around 90% efficiency, a heat pump could be over 300% efficiency, an example of this would be producing 3kW of heat from 1kW of electricity.

Maintenance Costs

  • As with anything mechanical, a heat pump will need regular servicing in order to keep it safe and running efficiently. Scroll down to see what’s involved in a heat pump service by Carters Plumbing and Heating.

Low Flow Temperature

Lower flow temperatures help to optimise the efficiency of a heat pump. Flow temperatures in the range of 35 to 50 °C have proven to be compatible with a radiator system linked to a heat pump.

To allow the heating system to operate with lower flow temperatures, it might be necessary to enlarge the heating surfaces. Since radiant heat is effective even at low temperatures, radiators with sufficiently large radiant surfaces are decisive when it comes to heating in the temperature range below 50 °C. This will also increase the cosy feeling of warmth.

Prior to installing a heat pump existing radiators should be checked mathematically in each individual case, taking into account the lower system temperature, and replaced if necessary. Even if some radiators are sized sufficiently, their age and condition should be considered. Moreover, hydronic balancing is an important factor as this ensures an even heat distribution in the pipe network and guarantees that every radiator receives the required amount of hot water.

Do I need permission to install a heat pump?

Before installing a heat pump, it’s important to check whether you need to apply for permission from your local planning authority. Most heat pump installations are considered ‘permitted developments’, which means that no permission is required. However, there are exceptions and it’s best to check with your local planning department before proceeding, especially if you live in a listed building or conservation area.

You are required though to register your energy device with your Distribution Network Operator (DNO), the company that is responsible for bringing electricity to the property where you are installing the device. To determine your relevant DNO, please visit the Electricity Network Association’s (ENA) website and enter the postcode of the installation site.

Which is the best type of heat pump for me?

Air Source Heat Pumps

An air source heat pump is relatively easy to install, as long as there’s a suitable place outdoors to position the unit. A heat exchanger will be installed and cables and heating pipes will be put through the wall of the house to connect it to the heating system.

There are two types of ASHP’s (air source heat pumps):

Air-to-Air - This is the most popular heat pump in the UK. In these systems, the heat is transferred into a conventional ‘wet’ heating system and this set-up gives you hot water and central heating.

Air-to-Water - A minority of UK ASHP’s are ‘air to air’. These transfer the heat into the air, which is distributed around the home, however they don’t provide hot water.

Ground Source Heat Pumps

The earth absorbs and stores heat from the sun year after year and just a few feet under the ground, there is a constant average temperature of 4-12 degrees Celsius. If you have some land to your property you may be able to opt for a ground source heat pump.

This is usually more expensive to install because of the additional labour. The ground will need to be dug or drilled so that pipes or bore holes can be inserted.

You will need to ensure that you have good access for diggers and other large pieces of equipment, as well as the right amount of space to lay the pipes - the bigger the home, the more pipework will need to be laid.

Water Source Heat Pumps

Water source heat pumps (WSHPs) are an extremely efficient way of heating water if you live in close proximity to a lake, river, stream, well or borehole.

As the name suggests they work by extracting heat from a body of water and turning this into energy that can be used to heat your home and supply you with hot water. As heat transfers better in water, homeowners typically find that they are more efficient than ground and air source pumps.

Hybrid Heat Pumps

There is also a hybrid ASHP available which can often be combined with an existing central heating system and traditional boiler.

With a hybrid ASHP system the heat pump provides a ‘base load’ for the day-to-day heating and hot water, with the boiler only firing up to provide hotter water or a quick heat boost during a particularly cold snap.

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Advantages

  • Heat pumps generate a highly efficient source of heat and hot water
  • They are environmentally friendly and can produce zero carbon if used with a renewable tariff
  • They can closely match the running costs of other home heating systems
  • Installation cost can be offset by the Boiler Upgrade Scheme, a scheme which the government offers £5-6000 towards the cost and installation of a heat pump system.
  • Heat pumps require low maintenance and have a long service life
  • Some systems can provide cooling in the summer
  • Retro-fitting is possible

Disadvantages

  • Heat pumps generate a lower output temperature than conventional boilers
  • In older properties they may work best as part of a hybrid system with a conventional boiler
  • You will need some outdoor space to house the unit
  • They can be expensive to install but the government’s Boiler Upgrade Scheme can help with a £5000 grant toward installation.
  • Some heat pumps can be noisy, however Viessmann’s pumps feature Advanced Acoustic Design, meaning that all components of the heat pump are designed to minimise noise.
  • They require additional electrical power to run them in extremely cold weather
  • Existing radiators and pipework may need to be replaced to get the best from your heat pump.

Heat Pump Servicing

Most heat pumps these days can last 20-25 years but to keep them in top condition it is recommended that they are regularly checked in line with manufacturers’ service instructions.

An annual service ensures that the pump is running efficiently and will improve its lifespan. Your heat pump could lose some efficiency over time, so a properly maintained pump could save you money too.

The list below details what is involved with a heat pump service. In some cases, failure to maintain the system to these recommended checks could result in the warranty becoming null and void.

Service Cost: £210 inc VAT

Mechanical

Mechanical

  1. Check the casing, pipe insulation and heat exchanger for damage and that the drain holes are not blocked.
  2. Check for signs of water pipe and refrigeration leaks.
  3. Check the air discharge space and check for fan and pump vibration.
  4. With the water supply turned off, remove the screen from the strainer in the combination inlet valve and clean off any dirt.
  5. With the water supply turned off and the hot water taps open, check the expansion vessel charge pressure and top up as necessary.
  6. With the water supply turned on, open the temperature relief valve and then the expansion valve to check unrestricted discharge into tundish. Check valves for freedom of movement and confirm that the water stops and both valves reseat correctly. Check at a full bore discharge from either valve that there is no back up or discharge over the tundish.
  7. Check that the correct outlet pressure is being maintained by the pressure reducing valve.
  8. Check and clean the buffer tank.
  9. Open the primary/heating system safety valve and check that it discharges safely.
  10. Drop the primary/heating system pressure to zero - check and, if necessary, top up the air side of the expansion vessel.
  11. If necessary, top up the concentration of the heating system inhibitor.
  12. Re-establish the primary/heating system pressure and disconnect the filling loop.
  13. Check the primary/heating system pressure does not rise above 2.5 bar and the safety valve does not drip when the system is at full temperature.
  14. Check and release any air from the primary/heating systems.

Electrical

Electrical

  1. Check condition of electrical isolated, that cables are tight and all connectors on PCB are secure.
  2. Visually inspect, checking for the presence of supplementary bonding and that it is being maintained.
  3. Check all electrical connections especially contactors and breakers.
  4. Check operation of flow switch
  5. Check that temperature sensors in tank are secure and check tank temperature.

Controller

Controller

  1. Check for the correct operation and temperature setting of the thermostats.
  2. Check the operation of the motorised valves.

Funding for Heat Pumps

You may be able to obtain funding for a heat pump through the government’s Boiler Upgrade Scheme.

Please call us for details: 01243 210246

Contact

01243 210246

hello@cartersheating.co.uk

Carters Plumbing & Heating, 83 Whyke Road, Chichester, PO19 8HU

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