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.
Heel pain is an extremely common complaint, and there are several common causes. It is important to make an accurate diagnosis of the cause of your symptoms so that appropriate treatment can be directed at the cause. Plantar Fasciitis. Plantar fasciitis is the most common condition that causes heel pain. Plantar fasciitis is due to irritation and inflammation of the tight tissue that forms the arch of the foot. Common symptoms of plantar fasciitis include heel pain with prolonged walking and standing.