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.
Symptoms & Signs. Pain in the heel can result from a number of factors. Abnormalities of the skin, nerves, bones, blood vessels, and soft tissues of the heel can all result in pain. Because of walking and daily movement, we are always at risk for injury or trauma to the heel area. Common causes of pain in the heel include blisters and corns.