Meet the Expert: Heat Pumps – How They Work, Savings & Costs

MNN Plumbing and Heating Limited shares his advice on heat pumps, how they work and possible costs and savings.

In recent years, the popularity of heat pumps as an alternative heating solution for Irish homes has been on the rise.

However, knowing if a heat pump is right for the home means understanding how they work, what the possible costs and savings are and what is required before installation to ensure a heat pump will work efficiently for a homeowner’s property.

Onlinetradesmen member, Michael Tracey from MNN Plumbing and Heating Limited in Dublin West has been very busy installing Heat Pumps over the past year.

This month Michael answers our questions on Heat Pumps as a renewable home heating solution.

Onlinetradesmen (OLT): What is a heat pump?

Michael Tracey: Heat pumps extract heat from the air, water or ground using the same technology similarly found in a refrigerator. However, unlike a refrigerator where warm air is extracted from inside the unit and vented outwards, a heat pump extracts heat from outside the unit and pulls it into water that circulates through a home’s radiators or underfloor heating.

OLT: What are the different types of heat pumps?

Michael Tracey:  There are 3 types of heat pumps:

• Geothermal
• Water-source
• Air-source

Geothermal heat pumps extract heat energy from the ground, which passes through a series of pipes filled with an antifreeze mixture. The heat pump then compresses this energy and pumps it to a higher temperature. The heat is then passed to the water that circulates through underfloor heating, radiators or hot water tanks.

The installation of a geothermal heat pump will depend on the subsoil and the size of your plot. Geothermal heat pumps are often perfect for rural locations and new builds where the site allows.

A water-source heat pump works by extracting heat from a water source like a lake or river. The operation and installation are similar to a ground-source heat pump – however, the big difference is that heat transfers better in water so a water-source heat pump has the highest efficiency of all heat pumps.

The most common heat pump installations in Ireland and the type we are currently busy installing are air-source heat pumps. An air-source heat pump transfers heat from the outside air and moves it to a warmer temperature for use inside the home.

OLT: Why have heat pumps grown in popularity in Ireland?

Michael Tracey: In 2008, Irish Building Regulations came into force, which required all new homes built to include at least one renewable energy source.

Because heat pumps offer high-energy efficiency standards and are regarded as a greener alternative compared to conventional heat systems, a high portion of new builds have had heat pumps fitted.

Demand has also grown for retrofitting existing heating systems and recent estimates indicate that at least 170,000 Irish homes are likely to swap out an oil boiler to a heat pump by 2023.

Homeowners are also keen to swap out or upgrade heating systems like oil-fired or gas boilers because of the availability of government grants, substantial electricity savings, environmental benefits, as well as growing confidence in heat pump technology.

OLT: How much can a homeowner save installing a heat pump?

Michael Tracey: A heat pump only uses electricity to power the pump as opposed to generating heat; therefore 4 units of heat produced will only require approximately 1kWh electricity compared with a typical domestic boiler, which requires approximately 30kWh of energy for the same output.

The efficiency of a heat pump means that a homeowner can save 40% or more on their existing utility bill. Some energy suppliers even offer special day and night rates for homes using heat pump systems.

OLT: What should a homeowner consider before installing a heat pump?

Michael Tracey: A heat pump home heating system is designed to operate at a set temperature, ideally between 20°C and 22°C.

If the heat level in the home constantly drops below a set temperature and a heat pump is working harder and longer to achieve this set temperature, then the homeowner’s electricity bills will inevitably be higher.

It should also be noted that running a heat pump at a higher temperature would also increase electricity requirements and utility bills.

So to ensure a heat pump’s efficiency, it’s really important that the heat produced is not lost through the walls, roof and floor of the home.

If a home was built before the 90s, chances are very high that the homeowner will need to reduce the amount of heat lost in the home by upgrading the home’s insulation before installing a heat pump.

OLT: Is a heat pump compatible with existing heating systems?

Michael Tracey: Yes, heat pumps can be integrated with existing radiators, underfloor heating, hot water cylinders and solar thermal systems.

When reviewing the installation of a heat pump, we review the heat output required and the size of the existing systems to meet heating requirements.

It’s always good to see how existing radiators perform before decisions are made to upgrade. In many cases, changing radiators will not be required following a heat pump installation. However, the key is to ensure that the radiators are correctly sized for the heat output required.

Underfloor heating often works very well with heat pumps, but if you have an older home, installing an underfloor heating system may not be practical.

OLT: How often will heat pump service and maintenance be required?

Michael Tracey: Typical service for a heat pump should happen once a year by a registered professional.

Service would include cleaning filters, coils and fans and ensuring airflow is good. Checks on refrigerant levels and pressure as well as any system leaks or electrical breaks will also be necessary.

With yearly maintenance, a heat pump should last 20-30 years or more.

OLT: How much does it cost to install a heat pump?

Michael Tracey: The costs for installing a heat pump will depend on the size of the house and the heat pump ratings.

A system can start from €8,000-€12,000 for the pump, tank and installation. If your home requires improved insulation, then this will also need to be costed.

While the cost to install a heat pump will be more expensive than replacing a current gas or oil heating system, payback will be quickly realised if you already have an inefficient oil or gas heating system.

If your system is relatively new and reasonably efficient, the expense may not be worth the heat pump upgrade – but it’s worth calculating the feasibility of the project and understanding the pros and cons.

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