The hybrid boiler (or hybrid heat pump)

We're big fans of the energy mix, and we've already told you about its many benefits in the Positive Energy magazine. With examples of combinations of appliances and energy sources, such as wood or pellet stoves and heat pumps. This time, it's the hybrid boiler, a "two-in-one" solution with a host of benefits. Find out more.

What is a hybrid boiler or a hybrid heat pump?

A hybrid boiler is a domestic heating system that combines gas and electricity. It is also known as a hybrid heat pump, or PAC hybrid. This type of system combines two appliance technologies : the very high performance condensing gas boiler  on the one hand, given that oil-fired appliances can no longer be installed, and the electric air/water heat pump on the other.

This type of equipment can provide heating and domestic hot water for the home.

How does a hybrid boiler work?

The operating principle is simple: depending on the conditions and parameters set by the user, either the gas boiler or the heat pump will be activated automatically at the time when it is most needed. For example:

- When the outside temperature is milder, priority is given to the heat pump, which draws heat from the air and transfers it to the indoor unit.

- Conversely, when the temperature becomes colder, or even negative, the gas condensing boiler takes over.

This intelligent real-time control requires no user intervention. The device automatically switches to the most appropriate system at any given moment.

What criteria does the system use to select the boiler or heat pump?

We said earlier that the outside temperature was a criterion in the choice of activating one unit or the other. That's true, but it's not the only one. Here are the three control parameters:

  1. Temperature: the heat pump's coefficient of performance (COP) comes into play. The COP is the ratio between the amount of energy consumed by the heat pump - electricity - and the amount of energy it produces. When this ratio becomes unfavourable to the heat pump, the system switches to boiler mode. This is the case when the outside temperature becomes more extreme and the heat pump has to consume more to provide the expected calories.
  3. Energy costs: this criterion takes into account changes in energy prices. Depending on prices, the system knows which energy is the least expensive for the user, and therefore which energy to favour. Since costs fluctuate, the data is updated annually by the technician when the system is serviced.
  5. Greenhouse gas emissions: this third criterion is simply based on the CO2 emissions of the two appliances, so that the one with the lowest emissions is preferred. This criterion is used less frequently because these two technologies have relatively low emissions.

"Gas when it's very cold, aerothermal energy when it's milder... Or how to intelligently combine fossil fuels and renewable energy. That's the principle - and the advantages - of mixed energy!


What does a hybrid boiler look like?

The system consists of two technical units:

- Inside the home, the gas boiler,

- Outside, the heat pump (PAC).

In terms of design and volume, both look like ordinary individual boilers and heat pumps! The two units are only connected by two pipes through which the refrigerant circulates.

The "brain" of this combined system, which controls the entire installation, is built directly into the indoor unit, in the boiler block.

The settings for the entire system (boiler + heat pump) will be made from a single interface: either the control screen on the boiler, the remote control or the smartphone application, as offered by some recent appliances.

The advantages of the hybrid boiler or hybrid heat pump

- The hybrid heat pump is eligible for financial aid.

- Flexibility = control = security. Few systems offer such adaptability. It's the choice of energy mix, so it's a long-term choice.

- There's no need to choose between electricity and gas: you can combine these two complementary energies and get the best out of both technologies.

- The hybrid heat pump features intelligent real-time regulation that optimises production and saves on energy consumption.

- The hybrid heat pump can be installed in both new-build and renovation projects (replacing an old gas or oil-fired boiler, for example). In the latter case, it is even possible to keep the old radiators in place, or the underfloor heating.

- The hybrid heat pump makes it possible to reduce the amount of fossil fuel in your energy mix. 

- With Outsteel, heat pumps located outdoors now benefit from an attractive, high-performance cladding and protection solution for perfect integration.