Can I buy a heat pump before reconstruction?
The less energy is needed to create a pleasant indoor environment, the better. Therefore, reconstructions leading to a reduction in the need for thermal energy are always useful. This applies to all heating systems, not just heat pumps.
Sometimes, however, the renovation of a building is not feasible in a short time. Fortunately, the houses do not need to be extensively renovated in order to use heat pumps. Of course, the operation of the heat pump is more efficient, the lower the heat loss. Of course, our wallet and the environment benefit from the lowest possible use of thermal energy.
Before the installation of the pump itself, it is definitely worth correctly calculating the heat loss of the object.
However, for the use of heat pumps, the required temperatures of the heating circuit are decisive. In many old houses, heat transfer systems are oversized. This means that when replacing the heating system, it is usually possible to lower the set temperature at the outlet in the system and operate the heat pump more efficiently. In many other cases, renovation steps have already been taken, such as replacing windows. This is also often enough to efficiently use the heat pump.
Efficiency can be positively influenced with the help of additional, relatively inexpensive measures that can be carried out in a short time. This includes, for example, the replacement of individual radiators. Modern radiators can transfer the same amount of heat to the room at a significantly lower temperature of the heating circuit. Such simple renovation measures can often be the first step in a medium-term renovation plan, which can later be used to achieve further efficiency improvements.
Another common prejudice is that heat pumps can only be used with underfloor or wall heating. However, this is a misconception. Radiators do not necessarily require "very high" flow temperatures. A field study was conducted in which the average temperature of the heating circuit reached above 45 °C only for a handful of air/water heat pump systems that were equipped exclusively with radiators. In most systems, temperatures were even below 40 °C.
Is it possible to warm existing buildings pleasantly with heat pumps?
The most important for residents is surely the question of whether the room temperature will be pleasant, even if it is very cold outside? The first two weeks of February 2021 were quite cold. A very recent evaluation of 20 air/water heat pump systems in which the measured values are continuously recorded showed the following: The average temperature of the outside air for heat pumps evaluated during this time was -3.6 ° C (As cold as it is, the fact that in the last 50 years there have been only 5 months with average temperatures below -3.5 ° C) shows.
The SCOP of the 17 systems (the top three in fully renovated houses were not taken into account) during this time was 2.3, with a range between 1.6 and 2.8 – that is, even in such cold weather, it was possible to produce more than twice as much heat could be generated from the surrounding air. The system with the lowest efficiency had to work with the lowest average outside air temperature of -10.2 ° C. Heating rods were used in only five systems and were taken into account when determining efficiency. The required heating was provided by all systems.
The fact that heat pumps can be successfully used even at very low outdoor temperatures is also shown by the fact that they are already widespread in countries with significantly harsher winters, such as Scandinavia. There are products on the market that can work even at -25 ° C without a heating element.
In addition to the air/water system, there are also geothermal solutions, that is, earth / water. Geothermal solutions are mistakenly perceived as very expensive. In fact, it is a more efficient technology than air / water and, in addition, it really does not have to be more expensive. But about this in the next article.
What happens if the heat pump is installed before renovation?
With regard to renovation, the following question is often asked: What happens if the heat pump is installed first, and later the building undergoes renovation? Would the heat pump then be oversized? The subsequent renovation will primarily bring an increase in the efficiency of the heat pump. Heat pumps provide the required heat both in mild autumn and in frosty winter, which means that they must be able to respond very flexibly throughout the heating season. Therefore, oversizing (except in extreme cases) is not a big technical problem.
In addition, heat pumps with inverter technology have now become almost standard, allowing the heat pump to control its performance and thus provide a flexible power range with high efficiency.
It is therefore clear that heat pumps can reasonably be used even in existing buildings. In principle, it is always better to renovate first, but it is not strictly necessary. In the vast majority of cases, a good heat pump solution can also be implemented without renovation (or slightly renovated). There are many companies that specialize in such cases.