Heat pumps are growing in popularity, with more and more people choosing them over oil or gas heating systems. Although they have higher installation costs than conventional fossil fuel heating systems, heat pumps offer an energy-efficient way of providing heating for your home. They are a greener solution too. If you are considering upgrading your system and installing a heat pump, here’s what you need to know.
How do heat pumps work?
Heat pumps are electrical devices that extract heat stored in the air or the ground and transfer it into your home. Heat-pump technology might seem new and complicated, but they are actually very simple. “We are all using this technology in our homes already with our fridges,” says Fergal Cantwell of Envirobead Retrofit.
A heat pump works exactly the same way as a fridge but in reverse. The system is made up of a compressor, an evaporator and a condenser. Heat pumps prioritise hot water, so you will have hot water on demand. This is one of the big benefits of heat pumps over conventional fossil-fuel heating systems.
What are the main types of heat pumps?
There are two main types of heat pumps: air to water or air to ground.
An air-to-water pump comes in two systems. One is a monobloc, where all of the kit is in the outside unit, which runs back to a standard hot water cylinder inside the house.
The other is a split system, with an indoor unit and an outdoor unit. The indoor unit, about the same size as an American fridge-freezer, has a super-insulated thermal store for hot water. You do not need a separate hot water cylinder with a split system. If you are tight on space, the monobloc is a good option as you won’t need to sacrifice space for the internal unit.
Air-to-water heat pumps are the most popular systems in Ireland at the moment. “Ninety per cent of the heat pumps we’ve installed this year are air-to-water and 10 per cent are air-to-air,” says Cantwell.
The reason for their popularity is the ease of installation. Air-to-water heat pumps have also improved in efficiency and have nearly caught up with ground-to-water heat pumps.
Ground to water heat pumps work by collecting the heat stored in the ground by heating water in a network of tubes buried underground. They are more efficient than air-to-water systems but are more expensive to install as they require excavation and a good bit of space.
Are there any brands that are better than others?
There are established brands in the market, the main two being Daikin and Mitsubishi. However, many of the fossil-fuel boiler manufacturers are starting to produce heat pumps, as oil and gas boilers will be phased out over the next few years.
When it comes to choosing a heat pump, it’s important to do your research. Compare the specifications of each unit and note any differences in efficiency. Always check with your installer to get their advice on the most suitable system for your home. The cost of a heat pump doesn’t vary much between suppliers. You can typically expect to pay between €10,000 and €12,000 for a new system.
How insulated does your home need to be?
To maximise the efficiency of your heat pump, it is important your home is very well insulated and draught-proofed. If you are applying for the single grant measure from SEAI for a heat pump, you will need to have a technical assessment done to establish whether your home is sufficiently well insulated to run a heat pump efficiently.
This assessment measures the heat loss in your house. SEAI will not provide grants for homes where heat pumps won’t run efficiently. “The potential of a heat pump is up to 400 per cent efficiency, so the better insulated your home is, the more chance you will have of realising that potential,” says Cantwell.
If you are successful in securing the grant and choose to proceed with installing the heat pump, you can claim €200 back from SEAI for the cost of the technical assessment on top of receiving a grant of €3,500 for the heat pump.
Can you use your existing radiators?
If your radiators are 15-20 years old, it’s likely they will need to be replaced. A heat pump will work with steel radiators. “Often it’s the sizes of the radiators that are not compatible,” says Cantwell. “When designing your system, you may find you need to change the size of one or two radiators, or you may need to replace them all.”
Heat pumps typically work best with underfloor heating or large radiators because of their lower operating temperature requirements. It’s important to size radiators and your heating system before installing anything; otherwise, you risk having a system that is overworking or underperforming. Your installer will carry out a survey of your existing system to check its compatibility.
In a retrofit situation, most people will locate the new internal unit either where their existing boiler is or where their hot water cylinder is. This is where the existing pipework is located, making it less costly and disruptive to install. You can put them anywhere, but these two locations are the most straightforward.
- Denise O'Connor is an architect and design consultant @optimisedesign