HTHOMETALLYTHE PRACTICAL HOME GUIDE

Heating/ CALCULATOR

Heating buffer tank volume

Estimate the water volume needed to absorb surplus heat for a chosen minimum heat-source run time.

Use the delivered heat output at the operating condition, not electrical input or fuel rating.
Use the heat accepted by the smallest zone or operating condition that causes cycling.
Confirm the appropriate minimum run time and cycling limit with the equipment manufacturer.
Use only the temperature range that the heat source, controls and emitters can actually use.
Include only connected water that participates during the short cycle.
Heat that must enter storage

8.0 kW

Heat stored during target run

2.7 kWh

Required participating water volume

229 L

Estimated additional buffer volume

149 L

Run time supported by existing water

7.0 min

Water is treated as 1 kg/L with specific heat 4.186 kJ/(kg·K). Heat-source output, active load and temperature swing are constant, and all stated water participates uniformly. Tank stratification, pipe and tank loss, control deadband, defrost, minimum flow, hydraulic separation and manufacturer minimum-volume rules are excluded. Final selection must follow equipment and safety requirements.

FROM ESTIMATE TO ACTION

Use the result, not just the number.

01

Verify the inputs

Measure or document each input. If a value is only an estimate, record its source and test a conservative alternative.

02

Keep the calculation traceable

Save the input link or copied result together with the date, units and assumptions. A number without its inputs cannot be checked later.

03

Confirm the decision

Compare the estimate with the related guide, current product data and requirements that apply at your location before buying or building.

Inputs to verify

Heat-source output during the cycle (kW)
Use the delivered heat output at the operating condition, not electrical input or fuel rating.
Minimum active heating load (kW)
Use the heat accepted by the smallest zone or operating condition that causes cycling.
Desired minimum run time (min)
Confirm the appropriate minimum run time and cycling limit with the equipment manufacturer.
Usable buffer temperature swing (°C)
Use only the temperature range that the heat source, controls and emitters can actually use.
Existing usable system water volume (L)
Include only connected water that participates during the short cycle.

Continue your calculation

Explore all calculators