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.
The most common local causes of heel pain include: 1  Plantar fasciitis â Plantar fasciitis is a painful inflammation of the plantar fascia, a fibrous band of tissue on the sole of the foot that helps to support the arch. Plantar fasciitis occurs when the plantar fascia is overloaded or overstretched.