The origin of heat pumps can be traced back to the 19th century. After a long period of practical development, both the types of heat pump technologies (such as water source heat pumps, ground source heat pumps, air source heat pumps, etc.) and the application fields of heat pumps (large commercial, small household, hot water, heating and cooling, etc.) have become very mature abroad. Especially in Europe, the birthplace of heat pumps, the development of heat pumps is relatively advanced. Let's introduce the classic engineering system diagrams of heat pump heating in Germany and Sweden and see how their heat pump heating systems work.
Heat pump heating project drawing in Germany
Multi-source coordination of solar energy, heat pumps, etc., with separate bathing water and heat pump water
Highlights:
1.Multi-source configuration: There are both solar energy and heat pumps, and even backup electric assistance.
2.The water for solar energy and the water for heating are both exchanged through water-to-water heat exchange, and the water is strictly not mixed.
3.The bathing water and the heat medium water are also exchanged through water-to-water heat exchange, and the water is strictly not mixed.
4.The heat medium water in each location is circulated daily by a small pump instead of being replaced by a large pump.
5.The recirculation of bathing hot water is essential to avoid water waste.
It can be seen that there are many valves, sensors, expansion tanks, etc. on the engineering diagram. It should be noted that this is just an ordinary household heating system. Many domestic consumers, dealers, and even heat pump manufacturers think it is simply unnecessary. The requirements for heat pump heating in our country emphasize good quality and low price, and savings are made wherever possible. This truly reflects the rigor of the Germans.
From the above heat pump heating engineering diagram, we can understand that in fact, every German family is built according to the standard of a heat energy station. This may also be the future development vision of domestic home systems - the home energy station, combined with home big data, to analyze where cooling is needed, such as refrigerators, water dispensers, air conditioners, and fresh air treatment, and send it there; where heating is needed, such as heating, drying, laundry, and bathing, and send it there, while recovering the cooling heat for standby use! But this is a very ambitious vision with a long way to go.
Heat pump heating project drawing in Sweden
Pump and three-way valve switching system, separate bathing water and heating water
Highlights:
1.The heat pump is the main heat source and is equipped with electric assistance.
2.The buffer water tank is standard, and there is a very clear calculation formula for size and capacity.
3.A three-way valve is used to switch the heat demand for bathing and heating.
4.The bathing water and the heat medium water are exchanged through water-to-water heat exchange, and the water is strictly not mixed, as in the German system.
5.This solution shares one water pump.
Two-pump system, separate bathing water and heating water
Highlights:
1.Multi-source configuration: There are both solar energy and heat pumps, and even backup electric assistance.
2.The water for solar energy and the water for heating are both exchanged through water-to-water heat exchange, and the water is strictly not mixed.
3.The bathing water and the heat medium water are also exchanged through water-to-water heat exchange, and the water is strictly not mixed.
4.The heat medium water in each location is circulated daily by a small pump instead of being replaced by a large pump.
5.This solution uses two pumps to meet the hot water and heating demands respectively.
Heat pump combined with wall-mounted gas boiler for radiator heating system
Highlights:
1.The heat pump is the main heat source and is also equipped with a wall-mounted gas boiler or electric auxiliary heating.
2.A three-way valve is used to switch the heat demand for bathing and heating.
3.The bathing water and the heat medium water are exchanged through water-to-water heat exchange, and the water is strictly not mixed, as in the German system.
4.This solution shares one water pump.
5.The radiators are all installed in parallel to reduce water resistance.
Two points can be summarized from the above heat pump heating diagrams:
1.Air source heat pump heating is very mature in Europe. Especially, heating with heat pumps and radiators is also mature abroad.
2.Regardless of whether it is the heat pump heating solution in Germany or Sweden, there are multi-source supplies, and domestic water and heating water are processed separately without water mixing.
Many Chinese people think that the bathing hot water should be hotter, preferably 50 - 60°C. How can water-to-water heat exchange achieve such a high temperature? In fact, when Europeans do water-to-water heat exchange, one is to ensure the reliability of the system; the second is that the water in contact with the body is very strictly required; and the third is that as long as the pipeline has good insulation and a perfect recirculation of hot water, the bathing hot water above 45°C is sufficient.
In addition, the load value of heat pump configuration abroad is basically 40 - 60 watts/square meter (w/㎡), which is simply not feasible in China. The main reason is that the building insulation in many places in China is poor. Although the country has raised the building energy-saving standards in recent years, the insulation situation of houses in rural areas, urban-rural fringes, and old urban areas has not changed. Especially for heating customers in the south, in the eyes of Germans, it is equivalent to no insulation!