Those who have radiators in their home often hear that the heat pump is not for them. And so many give up from the start, convinced that they need to redo the entire system or install a traditional boiler again. In reality, the latest generation technologies are able to work at high temperatures and take advantage of existing radiators without having to install a different heating system. Why is it possible to use a heat pump in renovations today without having to completely change your heating system?
Because it has always been said that the heat pump does not work well with radiators
For years it has been repeated that the heat pump is only good with underfloor heating and that with radiators a heat pump does not heat enough. These statements were correct, in fact the first heat pumps for residential use were designed to operate at low temperatures, between 35 and 45 °C. Traditional heating systems were and still are coupled with radiators, often made of cast iron. If they are made with this material, radiators are able to effectively transfer heat to the rooms only if the water inside them is at a temperature between 60 and 70 °C, which in the past could only be achieved with traditional boilers.
In practice, connecting a technology created for low temperatures to a system sized for high temperatures resulted in ineffective heating and high consumption. Today, however, the situation can change thanks to some technological improvements such as high temperature heat pumps.
How does a heat pump work and what changes with radiators?
The heat pump does not heat the water by burning a fuel like traditional boilers, but transfers energy from a source outside the home to the inside of the house. In the best known case, the heat pump takes heat from the outside air and returns it inside our home thanks to a refrigerant gas which is compressed and expanded depending on the operating mode. Heat pump technology allows you to obtain up to 3 or 4 kWh (kilowatt hours) of thermal energy, i.e. heating, for every kilowatt hour of electricity consumed. The heat pump, in fact, only needs electricity to function, and its efficiency in transferring heat is expressed by the COP (Coefficient of Performance) or by the SCOP (Seasonal COP).
When the heat pump is coupled with radiators, the critical point of the heating system is the temperature of the water leaving the heat pump. In the past, in fact, the increase in the temperature of the outlet water was slower than the increase in the electricity consumption of the heat pump. In other words, a higher water temperature increasingly worsened the efficiency of the heat pump, leading professionals to advise against combining it with radiators, designed to work with water between 60 and 70 °C. The old heat pumps also had a limited operating range, that is, they were physically unable to heat the water beyond a certain temperature. This limitation of their operation occurred if the external air conditions were particularly unfavorable, especially in the case of very low air temperatures and very high humidity.
R290 and high temperatures: because today radiators are no longer a problem
New generation heat pumps use R290 (propane) gas as the refrigerant. Thanks to this gas they are able to overcome the two main critical issues of previous generation heat pumps. The use of R290 gas allows you to produce water at higher temperatures than traditional heat pumps, reaching levels comparable to a gas boiler. Furthermore, the greater performance of R290 heat pumps allows for an increase in the operating range and allows the limits imposed by very harsh climatic conditions to be overcome. To give a practical example, there are some heat pumps, such as the EDGE PRO or EDGE F models from Clivet, which reach a water temperature of 80 °C and 75 °C respectively even with external air temperatures below zero. These new generation heat pumps manage to improve efficiency by 40% compared to older technologies even when heating water to temperatures comparable to gas boilers. For these reasons, the new generation of heat pumps is suitable to be coupled with existing radiator systems. In most cases it is therefore possible to reuse the radiators already present in our homes, even cast iron ones, avoiding invasive interventions such as demolishing floors to install an underfloor heating system.
The advantages of R290 heat pumps are greater when comparing their installation with that of a latest generation condensing boiler. This type of boiler reaches maximum efficiency only when it produces water at around 45°C. Their operation requires the recovery of the heat contained in the exhaust fumes, but if the boiler must produce water at 60°C to be coupled to the radiators, this recovery cannot occur. As a result, the efficiency of the boiler decreases and the system does not work in ideal conditions, making R290 heat pumps a generally more suitable solution.
The advantages of renovation with a heat pumpAnd
By coupling a new heat pump operating with R290 refrigerant gas to the existing heating system, several advantages are obtained:
- Greater thermal comfort: by exploiting the greater efficiency of heat pumps, it is possible to constantly maintain the temperature in the radiators at levels slightly lower than those of gas boilers, at around 55°C. Radiators no longer work with alternating on and off phases, as happened with gas boilers, but continuously transmit heat throughout the day, increasing thermal comfort in the room. In fact, peaks of heat or cold are avoided and a constant temperature is maintained throughout the day.
- Using the house as a heat storage: by leaving the heating system always on, you use your home as a heat storage, preventing the temperature from rising or falling too much. In this way, although the heat pump remains on for longer than a gas boiler, the cost of the bill decreases or, in the worst case, remains unchanged. This happens because the heat pump has a much higher efficiency than the gas boiler and by using the house as a thermal storage it is able to work in the best possible efficiency conditions.
- Use for cooling: Heat pumps can reverse their operating mode and be used for cooling in summer. This is possible in combination with suitable environmental terminals.
- Use for the production of domestic hot water: heat pumps can also be used to heat the water we use for showering, washing hands and for all what are technically called sanitary services. In fact, like gas boilers, heat pumps can be used not only for the heating system, but also to produce all the hot water needed in the home.
- Interruption of the gas supply: When forms of electric cooking are present, the installation of a heat pump allows you to eliminate the gas user and the related fixed costs. Furthermore, by not using gas at home, no combustion gas emissions typical of the boiler are produced, given that the heat pump only uses electricity.
- Possibility of coupling with a photovoltaic system and storage battery: the heat pumps work only via electricity and can be coupled to a photovoltaic system to reduce the cost of energy, keeping in mind self-consumption.
