As a standard immersion heater is 3KW, so it would take 2 hours to heat 100 Litres of water. After an hour and a half, it will only have reached about 53 degrees.....
Another common cause of heel and calf pain is Achilles Tendinitis. Symptoms are frequently described as an aching pain in the back of the lower leg and just above the heel. This sensation is typically worse after exercise and upon first waking up in the morning.
(See Anatomy of the Foot and Ankle). Gait abnormalities can cause inflammation of the structures attached to the heel bone, resulting in heel pain. Inflammation of the plantar fascia, called plantar fasciitis, is the most common cause of heel pain.Plantar fasciitis often causes pain that is more severe following a period of rest (e.g., after sleeping).eel pain also is relatively common in active children and adolescents between the ages of 8 and 13. Pediatric heel pain frequently occurs on the bottom rear of the heel or the sides. Heel pain occurs in both heels (bilaterally) in less than 30 percent of cases. The left heel is commonly the first to be affected.