A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave.
Some causes of cold intolerance are: 1  Anemia. 2  Anorexia nervosa. 3  Blood vessel problems, such as Raynaud phenomenon.  Chronic severe 1  illness. General poor health.  Underactive thyroid 1  (hypothyroidism) Problem with the hypothalamus (a part of the brain that controls many body functions, including body temperature)
Hot and cold symptoms can be incredibly disturbing. They may prevent you from sleep and cause you to feel like something is wrong. They occur during periods of intense anxiety, during anxiety attacks, or sometimes simply at night when your mind is too active.Only a doctor can diagnose the cause of your hot and cold symptoms, but these flashes are very often caused by anxiety.hey occur during periods of intense anxiety, during anxiety attacks, or sometimes simply at night when your mind is too active. Only a doctor can diagnose the cause of your hot and cold symptoms, but these flashes are very often caused by anxiety.