Tank Heating Time Calculator
Estimate how long an electric or steam heater takes to heat a tank of liquid from one temperature to another, taking heat loss to ambient into account, or the heater power needed for a set time.
- m × c = 8,380 kJ/K
- t = (mc ÷ UA) × ln[(P − UA(T₀ − Ta)) ÷ (P − UA(T₁ − Ta))] = 3.545 h (212.7 min)
Heat Up Time Formulas
No heat loss: t = m × c × (T₁ − T₀) ÷ P
m is the liquid mass, c its specific heat, P the heater power delivered to the liquid, UA the tank heat loss coefficient (U × surface area) and Ta the ambient temperature. The liquid is assumed well mixed and the tank wall heat capacity is ignored; add the steel mass × 0.5 kJ/kg·K to m × c for heavy tanks.
Worked example
2000 kg of water heated from 15 to 60 °C by a 30 kW heater with UA = 20 W/K takes about 3.55 h; without losses it would take 3.49 h, because the loss is under 1 kW.
Frequently Asked Questions
What is UA?
The heat loss per degree of temperature difference between the tank and ambient, the sum of U × A over all surfaces. It is in W/K.
Does this work for steam coils?
Yes, enter the coil duty as heater power. Coil duty falls as the liquid approaches steam temperature, so use an average value.
Why is mixing important?
Without agitation the liquid stratifies, and the temperature sensor may read the hot or cold layer.
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