Find out how many minutes it takes to bring a wash, low wines or water to the boil and how many kilowatt-hours it uses. You can also compare times for heaters of different power.
What does heat-up time depend on?
On the amount of liquid, the temperature difference, heater power and heat losses. An uninsulated boiler loses up to 30% of the energy to its surroundings, so insulation noticeably shortens heat-up and lowers the electricity bill.
How do I shorten heat-up?
Heat at full power until the column starts to warm up, then reduce to working power. A second heater used only for heat-up helps, as does a thermometer with an alarm that tells you when the temperature is reached.
How we calculate
Heat Q = m × c × ΔT, where m is the liquid mass, c the specific heat (water 4.19 kJ/kg·K, wash approx. 4.0) and ΔT the temperature difference. Time t = Q / (P × efficiency).
Frequently asked questions
How can I shorten the heat-up time?
Insulate the boiler (mat or thermal jacket), use a stronger or a second heater for heating up, and reduce the power with a controller once the temperature is reached.
Can I heat on an induction hob?
Yes, if the boiler has a ferromagnetic steel bottom (a magnet sticks to it). An induction hob is about 85–90% efficient, similar to an immersion heater.
Why does heat-up take longer than the calculator says?
The most common reasons are lower mains voltage, scale on the heater, an uninsulated boiler or a cold room. Check the heater power in the power calculator and descale the heater.
At what temperature does a wash boil?
A wash of about 10–12% starts boiling at about 91–93°C, and 40% low wines at about 84°C. The more alcohol, the lower the boiling point.