When focusing on ecological heating solutions, it is worth paying attention to heat pumps that are becoming more and more popular as the most ecological way of heating. Heat pumps for heating a building use renewable energy, accumulated in the ground, water or air. Its principle of operation is based on the typical physical changes that occur in the device: evaporation, compression, condensation and expansion. Heat pumps significantly reduce the consumption of fossil fuels and reduce the emission of pollutants into the atmosphere and reduce the heating costs of a building. Due to the fact that they work in an automatic manner, their use is very convenient. The installation of a heat pump is one of the methods of heating a house with renewable energy. In Poland, heat pumps are not very popular yet because most people are convinced of the high costs of installing such a system. Nothing could be more wrong for a heat pump installation to be more profitable than a gas or oil boiler room. The cost of installing a system based on a ground-source heat pump at home, which is inhabited by a family of four and an area of 200 m2, is approximately 64.5 thousand. Golden. The construction of a gas boiler room for the same space costs 54 thousand. PLN, while the oil boiler room is 74 thousand. zł. The most expensive elements of a heat pump system are: the purchase of a pump with the construction of a heating node, a hot water tank and the execution of the connection of the lower vertical or horizontal collector. Prices of wells are constantly falling, thanks to which the vertical collector is only a few percent more expensive than the horizontal collector. As a result, we save the plot area and obtain a guarantee of a stable energy source. The most common heat pumps are brine-to-water heat pumps, but there are two more types: air-to-water and water-to-water.
Water-water pumps use underground watercourses as the bottom source. The pump draws water from one well and dumps it into the other, min. 15 m towards the watercourse. Such a solution requires above all the availability of underwater streams of adequate efficiency. The watercourse efficiency can not change over the period to which the pump is intended to operate, ie 25-30 years. The water flowing through the pump is mineralized, which causes rapid corrosion is another disadvantage of this type of pump. There is no phenomenon that is characteristic of a central heating installation in which the same water circulates all the time, which quickly precipitates minerals and becomes neutral for the elements of the installation.
Air-to-water pumps use outdoor air as an energy source. This type of pump is easy to use because it does not require the construction of an expensive lower heat source such as vertical probes or a horizontal collector in the ground.
However, the brine-to-water water heat pump is the most effective. In this solution, solar energy accumulated in the ground is supplied to the pump. There are two types of so-called exchangers: vertical and horizontal. Brine-water pumps use the fact that the ground temperature below 1.5 m is approximately constant and amounts to 7-80C. This allows you to obtain the temperature of the circulating agent which is most often glycol solution at around + 40C, which is very effective for the pump. The pump with the help of a compressor raises the temperature to + 350C with very good efficiency. At the moment, brine-to-water heat pumps are the most efficient and stable devices that use renewable energy for heating purposes.
It is not true that:
The Heat Pump is very expensive – a well-installed heat pump allows heating bills at home to be significantly reduced and the outlays incurred for investments are quickly returned. For this to happen, it is recommended to use pumps with underfloor heating (where the required water temperature is between 35-40 ° C) or with a fan convector (the water temperature must be between 40-45 ° C). And because heat pumps are an ecological solution, there are subsidies for ecological heating. Heat pumps in low temperatures are inefficient
In the case of air / water heat pumps. For example, when the temperature drops below -5 ° C, and the heat demand in the building can not be fully ensured by the heat pump, as its power gradually decreases as the outside temperature drops, then additional heating is activated through the built-in electric heater. Thanks to the latest technology, heat pumps have achieved effective functioning at temperatures as low as -20 ° C. Land heat pumps use deep water, water that is deep below the surface, where the temperature is practically constant throughout the year, in contrast to external temperatures, where there are significant fluctuations. In Poland, the temperature of groundwater at a depth of more than 6m has an essentially constant temperature, which is about 10 ° C, regardless of whether it is winter or summer (you can expect changes in the range of 7-12 ° C).
Heat pumps are used only for heating. There are heat pumps that have a cooling function by reversing the cycle, they constitute a complete unit with the possibility of switching from heating to cooling. Cooling takes place using fan convectors and is recommended. The water temperature therefore contributes to the exchange of heat between the refrigerant and water, both during heating and cooling, which leads to the highest COPs. The higher the water temperature, the higher the COP value when heated, which also affects the cooling performance.
Heat pumps are very loud The first heat pumps having old compressor technologies have a higher noise level of 76 dB for the outdoor unit. The sound power level of the outdoor unit during heating is 54-57 dB, depending on the size of the pump. The acoustic pressure is between 35-38 dB at 5m and between 29-32 dB at 10m, if the outdoor unit is in the front of the building. These values are reduced by 3 dB, provided that the outdoor unit is self-sufficient. At corner mounting, the sound pressure values increase by 3 dB. The sources of noise are fans and compressors. In recent years, there have been significant changes in compressor technology, and noise levels have dropped significantly, especially for scroll compressors compared to piston compressors that were used at the beginning.
Heat pumps can be used only in new buildings are a perfect solution for thermo-modernization of existing buildings. The most important aspect is choosing the type and capacity of the pump. The following issues must be considered: heat distribution devices, operating temperature, building insulation and the availability of an appropriate heat source for the heat pump. Air-to-water heat pumps are recommended in homes, and ground pumps are suitable for new constructions because they require a drill change. Another recommendation is that in the case of old constructions it is necessary to assess the thermal losses that may result from faulty insulation or leaking windows and may have an indirect effect on the efficiency of heat pumps.
Heat pumps take up a lot of space and occupy more or less the same space as a gas condensing boiler. In both cases, a boiler room with a cubature (minimum 6.5 m3) is required for a heat source up to 30 kW with a closed combustion chamber and air supply from the outside.
Heat pumps require frequent inspections. Heat pumps are devices with a very low failure rate. However, we must remember that they contain mechanical components that are subject to exploitation. Just as gas furnaces require annual inspections, heat pumps should be inspected before the heating season, so in August / September they allow, among others, control the degree of their consumption and check other elements that affect the performance and the operation of the device.
Important parameters to be considered when selecting a heat pump:
area of heated rooms
demand for hot water
type of heating
thermal demand of the building
Advantages of heat pumps:
low operating costs
no need to build a chimney and ventilation
zero emission of pollutants
high reliability of the device
Disadvantages of heat pumps:
high purchase price for the pump and system components
decreasing performance with age system