Simple ways to save with a Heat Pump Boiler

Switching off gas completely in an existing home all at once is a step too far for many people. Most people would like to reduce their gas consumption, but taking out the entire central heating system is usually a bit much to ask. A complete switch from gas to a home heated comfortably by a heat pump system requires a large investment and a lot of installation work.

For those who prefer to start smaller, there is the heat pump boiler. This device provides  the necessary hot water for bath, shower and kitchen, helping to reduce gas consumption by at least 20% for most homes. In itself, this does not necessarily mean that you save energy, because instead of gas, electricity is used to produce the hot water: so it is primarily just a shift from one energy source to another. But thanks to the fact that heat pumps are so much more efficient than gas boilers at producing heat, the amount of electricity required is a lot less than the equivalent amount of gas. This alone will reduce your energy bill by hundreds of euros per year.

But for people with solar panels there is also another financial incentive to purchase a heat pump boiler. By controlling the device in such a way that it mainly uses electricity when the solar panels are working, the share of self-consumption can be increased. This means that less electricity is consumed and less excess solar energy is returned to the grid. With the feed-in costs that energy suppliers now charge, this means a significant additional saving on the annual bill.

As you can see: there's reason enough to get yourself one. But what exactly does it involve?

How does a heat pump boiler work?

In a heat pump boiler all the different parts are put together in one compact device (source: Vaillant)

Heat pump boilers consist of three separate parts. The heart of the device is the actual heat pump: a device that produces hot water using electricity and warmth from the outside air. The second part is the air supply and exhaust: the outside air is sucked in with a fan and led to the heat pump, and the (colder) air that the heat pump emits is blown out. The third component is the boiler: an insulated vessel with a capacity of e.g. 200 liters, which stores the hot water until it's needed in the home.

The great thing about the heat pump boiler is that these three parts are all in one compact device. Other heat pump systems often involve a separate outdoor unit with a large fan that is placed e.g. in a garden or on a roof, and which is connected to an indoor unit via pipes filled with coolant. Such a system requires a lot more installation work. A heat pump boiler is far less complicated: everything is combined neatly together in a single device.

Still, the outside air has to be supplied to the device and released back. Air vents must therefore be mounted with a hole through the wall or roof to the outside. The supply and exhaust should preferably not be too close to each other, because then the colder expelled air may be accidentally sucked back in, which reduces efficiency.

More than 100% efficiency, how is that even possible?

Regarding that efficiency: a heat pump is often said to have an efficiency of around 300% or higher. But how can a device be more than 100% efficient? That's because the efficiency is calculated on the basis of power consumption and not on the consumption of heat from the air. A normal boiler with an electric coil for heating has an efficiency of, for example, a maximum of 90%, because only electrical energy is used as a basis for the hot water. However, a heat pump can produce much more hot water with the same amount of energy, because in addition to electricity, heat from the outside air also serves as a source. This is how they get to those high efficiency values ​​of well over 100%.

The boiler tank is connected directly to the water pipes in the home. The input is cold water, and the output goes to the existing gas boiler input. Since the water from the boiler tank is already hot, the gas boiler does not switch on when hot water is needed for the tap. The gas boiler will only step in if at any time more domestic hot water is required than the boiler has in store.

Installing a heat pump boiler consists of the following steps: placing the device in the right place; connecting the water pipes and filling the boiler tank with water; installing the vents for air supply and exhaust, including the holes through the wall or roof; and of course plugging the power into a socket.

Smart control

Our installers will modify the settings using the display on the device

For people with solar panels, the final step is of course configuring the smart control based on solar power. We use the 'SG-ready' connection on the device for this. Our technicians program the heat pump boiler in such a way that at times when there is plenty of sunshine, the temperature in the boiler tank is set about 10 degrees higher than usual (for example 60 instead of 50 C). A control device such as the Sunny Home Manager or the Homewizard controls the SG-ready connection: our service department takes care of the correct configuration. Sounds pretty straightforward, doesn't it? We put this into practice at our colleague Joris's home 6 months ago: time to see how exactly that turned out.

The savings in practice

Joris lives in a terraced house with his wife and two young children. The heat pump boiler has reduced their gas consumption by approximately 170 m3 in the first six months of the year: on an annual basis this would be approximately double, so 340 m3. With a gas price of about € 1.45 per cubic meter this would result in € 493 of savings in one year. But of course the heat pump boiler has consumed quite a bit of electricity. We measured exactly how much power the device consumed using a smart socket: in the first six months it was 550 kWh, so on an annual basis that would be approximately 1100 kWh.

If all that electricity came from the grid at an electricity price of 30 cents per kWh, the hot water supply would cost approximately 1100 x 0.30 = € 330 per year. Compared to gas, this already means annual savings of € 493 - € 330 = € 163.

But of course not all of that power came from the grid. In fact, thanks to smart control by the Sunny Home Manager, the heat pump boiler managed to get about 70% of the required power from the solar panels on the roof. That percentage differed considerably between winter and summer: for example, in February the device only drew 35% of its power from the sun, while in June that percentage was no less than 90%.

We can therefore disregard 70% of the device's electricity comsumption, because it came from the solar panels and was therefore more or less 'free' (which is admittedly not entirely correct, because if that electricity had been fed into the grid, it would still have been worth something). If we calculate this way, the heat pump boiler only needs 30% of 1100 kWh of grid power in a year, i.e. 330 kWh, which would cost € 99. So then we're looking at a saving compared to gas of € 493 - € 99 = € 394 per year!

Hundreds of euros per year

Via the SMA Energy app or via Sunny Portal can see the heat pump boiler power consumption, plus what percentage was supplied by the PV panels

It turns out that a heat pump boiler, if controlled intelligently, can indeed save hundreds of euros per year for an average family. And it does this without any sacrifice in terms of comfort: Joris assures us that there is always delightfully hot water available from every tap in the house.

We have to be honest however; a heat pump boiler including installation is still quite an investment. If we compare the investment with the annual savings, it's not as if the money suddenly comes pouring in. But the fact remains that you can save a lot with the relatively simple installation of a compact heat pump boiler:

• You save a lot of gas consumption in the home, and
• You save a significant amount of money on your annual energy bill, and
• You save the environment by emitting fewer greenhouse gases

Our experience at Joris's home has made us enthusiastic about the product, leading us to include the heat pump boiler in our range and to offer it to our existing and new customers. Curious about the possibilities at your home? Please contact us, we'd be happy to see if it might be something for you!