1. If the buffer water tank is not used, it will cause the host to start and stop frequently. Due to the limited amount of circulating water in the loop, then it will cause the host to reach the design temperature in a very short time, the host will stop working, and then in a very short time, the water temperature will reach the starting condition of the host, and the host will start again, so that the frequent start will greatly reduce the service life of the host and waste of electric energy. Not only is it necessary to buffer the tank, but the capacity of the tank should be a little larger.
2. Efficient defrosting, short defrosting time. When used in severe winter, especially between -3 and 5, the main engine frost is obvious, and the impact of defrosting on the indoor temperature is a headache. Because the unit needs to consume the heat in the pipeline during reverse refrigeration, if the water volume of the water system is small, the defrosting time will increase, and the water temperature in the pipeline will be low, and the defrosting effect will not be good. If a buffer water tank is installed, then in the process of defrosting, because there is a certain temperature in the water tank, the defrosting can be completed in a short time, and the heat consumption is also small, which avoids the fluctuation of indoor temperature caused by the defrosting of the main engine, and has a great effect on stabilizing the terminal effect of the system.
3. It can ensure the smooth flow of water in the system, complete the automatic exhaust, and avoid the failure of the unit. We know that when the water tank is placed in the return system, the circulating water enters from the upper part of the water tank and discharges from the lower part, so that the gas in the water will accumulate in the upper space of the water tank, and the pressure in the closed system will automatically force the gas to be discharged from the upper exhaust valve, so that the water outlet at the bottom of the buffer tank is connected to the suction port of the water tank because there is no gas, so it can not only protect the impeller of the water pump, but also make the system free of gas to ensure the normal operation of the host. If there is no buffer water tank, then the presence of gas will cause the main engine to sometimes have a flow switch failure and a high pressure alarm.
4. It can make the sewage discharge of the system more thorough and prevent the system from being blocked. In our system, there are a large number of impurities, which will slowly accumulate to the bottom of the buffer tank through circulation, and when they pass through the Y-filter, the water quality of the pump will become better, thus reducing the cleaning of the Y-filter.
Second, the size of the buffer water tank is selected.
Method 1: Buffer water tank capacity The amount of water required for system stability The actual water volume of the system.
Firstly, the water required for system stability is calculated, and the water required for system stability is set to m1, then m1 qt (c t), where q is the heating unit of the unit is kw; t is the defrosting time, the unit is seconds, c is the specific heat capacity of water, take 4187, t is the maximum allowable drop of water supply temperature, take 3.
The actual water volume of the system = the water capacity per meter of the floor heating pipe and the total length of the system pipe. If the end is a radiator, the water capacity of the radiator is also counted.
For example, a brand machine in Beijing, 150 square meters, with 7P low-temperature heat pump heater, heating 20kw, the water required by the system is 20 4 60 (4187×3）=382（l)。
The actual water capacity of the system: with the 20 pipes commonly used in the north, the water capacity of 20 pipes per meter is about 0314L, according to a square of about 5 meters of pipe, the actual water capacity of the system is about 235L.
Therefore, the volume of the buffer water tank needs to be 382L 235L = 147 (L), and 150L can be used for actual installation.
Method 2: If you are doing household heating for the first time, you don't know how to calculate, you can use 100L and 150L to match, that is, regardless of the size of the system, the buffer tank is equipped with 100L or 150L, and these two models are usually available, which is enough to meet the needs of most projects.