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.
Plantar fasciitis is probably the most common cause of heel pain. Symptoms come on gradually and are often worse first thing in the morning. The plantar fascia is the tissue under the foot which forms the arch.