1. Because of water pressure instability or tap water pressure is too large, making the hot water heater does not come under;
2. First observe the hot water valve switch is not open large, or the cold water valve off small; if still can not increase the water supply valve to increase hot water outlet pressure, or the water heater bold;
3. If this phenomenon occurs in winter, the outdoor pipeline may be frozen and it is necessary to check if the electric heating cable is started or failed.