When the independent air source heat pump is used for indoor heating or cooling in each house, and it is also used as the domestic hot water source or the auxiliary heat source of solar domestic hot water system, the heating amount of domestic hot water can be calculated according to the following formula:
Where: QRS -- heating capacity of domestic hot water (kw);
VR -- domestic hot water storage volume (L), which is determined according to the amount of hot water used by sanitary appliances at the same time. When only one shower is considered, 70-100l can be taken;
C -- specific heat of water, 4.187kj / (kg ·℃);
ρ R -- hot water density (kg / L), which can be approximately taken as ρ = 1;
TR -- maximum temperature of heated water (℃), tr ≥ 40 ℃;
When the initial temperature of the water tank is 20 ℃, the temperature of the water tank is set at 10 ℃;
TR -- heating time (H), not more than 1 h
Model selection and installation 1： For air source heat pump units cooled in summer, the following coefficient of performance shall meet the requirements of current building energy conservation standards in Beijing:
1. The coefficient of performance (COP) of the chiller / heater unit under nominal conditions;
2. The comprehensive coefficient of performance (IPLV (c) of multi unit refrigeration system.
2： The heat supply performance of the selected air source heat pump unit shall meet the provisions of Article 1, 2 and 4 at the same time. When the unit is used as the heat source of the domestic hot water system, it shall also meet the provisions of paragraph 3.
1. The operating performance coefficient of heating design condition should not be less than 2.0.
2. In the area where the outdoor heating calculation temperature is equal to or higher than - 12 ℃, the unit shall be able to provide heat in an environment not lower than - 15 ℃. Low ambient temperature air source heat pump units should be used in areas where the outdoor heating calculation temperature is lower than - 12 ℃.
3. The outdoor temperature is the heating condition when the outdoor temperature is the local heating outdoor calculation temperature, and the maximum water supply temperature should not be lower than 50 ℃.
4. It should have advanced and reliable defrosting control, and the total defrosting time should not exceed 20% of the operation cycle time.
3： The setting of outdoor host of air source heat pump shall meet the following requirements:
1. Ensure that the inlet and exhaust air are unobstructed, and there is no obvious short circuit of airflow between the discharged air and the inhaled air;
2. Avoid the influence of dirty air flow;
3. The noise and heat emission meet the requirements of the surrounding environment;
4. It is convenient to clean the heat exchanger of outdoor main engine;
5. The defrosting water should be discharged in organization;
6. The upper part of the main engine should be protected from snow.
4： The design of air conditioning and heating water system shall meet the following requirements:
1. The closed system shall be equipped with expansion tank and safety valve, and water supply and pressure setting shall be carried out according to the following provisions:
1) The minimum pressure value should ensure that the highest pressure of the system is higher than the atmospheric pressure by more than 0.01Mpa; 2) The make-up water pressure should not be lower than the minimum pressure required by the system; 3) The opening pressure of safety valve shall not be higher than the pressure bearing capacity of system equipment, pipeline and accessories. When adding 2 - antifreeze solution into the main engine, the anti freezing device should be installed in the outdoor water circulation system.
5： The installation position of refrigerant water heat exchange device, water pump, expansion tank and other supporting equipment shall meet the following requirements:
1. When separated from the outdoor host, it should be installed in the room where the ambient temperature is not lower than 5 ℃, and should not be set in the bedroom and other rooms with higher requirements on noise standards.
2. There should be enough maintenance space around the equipment.
3. There should be drainage facilities on the ground near the installation location.
6： The length and height difference of refrigerant piping between equipment shall meet the product requirements.