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.
Plantar fasciitis. Overview. Plantar fasciitis Plantar fasciitis is an inflammation of the fibrous tissue (plantar fascia) along the bottom of your foot that connects your heel bone to your toes. Plantar fasciitis can cause intense heel pain. Plantar fasciitis (PLAN-tur fas-e-I-tis) is one of the most common causes of heel pain.