The most common household vacuum tube solar energy on the market is a non-pressurized natural falling water heater, where the tank normally works at 0 pressure, meaning that the pressure inside the tank is equal to the atmospheric pressure, and once this condition is broken, the tank will deflate or crack.
Solar water heaters in the use of the tank deflated or cracked mainly for the following two reasons.
(1) Blockage of the exhaust port
After the exhaust pipe blockage, when the water tank on the water, the internal air can not be discharged immediately, the pressure increases, higher than the external pressure, resulting in the tank up broken; and water, the external air can not be instantly replenished, the internal pressure of the tank is reduced, lower than the atmospheric pressure, resulting in the tank deflated. If the tank is empty after the sun, the air temperature inside the tank is very high, if the water, the internal air temperature decreases, the pressure decreases, the pressure difference between inside and outside is not balanced, which will also cause the tank to deflate.
Causes of exhaust pipe blockage are as follows.
1.1, the regional winter temperature is too low caused by: winter cold areas at night the temperature is too low, easy to frost, and frost condensate beads in the tank when discharged by the frost body intercepted to form a frozen body attached to the inner wall of the exhaust pipe, to a certain thickness will block the exhaust pipe. Therefore, it is recommended that the exhaust pipe should also do a good job of anti-freeze insulation measures for such areas. 1.2, incorrect installation: mainly incorrect installation of the exhaust pipe diversion, snowflakes are easy to accumulate to the upper end of the orifice to form a freeze blockage, this failure is prone to occur in northern areas after continuous overcast snow; or installers in the installation did not pay attention to the road exhaust pipe on the "keep open, strictly prohibited Clogging" signs, after the installation is completed, there will be no exhaust pipe on the plastic protection wire removed will also form exhaust pipe blockage, etc. will cause the tank to deflate.
1.3, the user's private modification leads to: the behavior destroys the principle that the upper end of the exhaust pipe must be kept open; or add an elbow up. The overflow pipe used is a plastic hose, deformation caused by the blockage, so that the tank can not exhaust also cause damage.
(2) tank insulation layer of secondary foam
Solar water heater tank insulation material for polyurethane, using high-pressure foaming equipment, and after constant temperature, foaming, maturation, curing four processes, a one-time overall foaming, closed-hole rate of 98%. Some small manufacturers or small workshops in the production of water tanks, the use of unqualified raw materials, or process parameters are not strictly controlled, not after high-temperature curing process, once the water temperature rises, the insulation layer will be the second foaming, so that the tank in the process of use, resulting in deflation (liner extrusion deformation) or outer skin up broken
