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.....
Podiatrists cite Plantar Fasciitis as being the most common cause of heel pain. Typical symptoms of this condition include sensations of pain, burning or heat in one or both heels.
Underpronation is also a factor of the most common cause of heel pain, which is plantar fasciitis. Along the bottom of the foot is a tough ligament called the plantar fascia. This ligament attaches to the heel bone and runs the length of the foot towards the toes.