This resets every field and clears the calculation. If a project is open, its hot water section is removed from the report. It can't be undone.
Tap the ⋮ menu (bottom right), then Guide, for the full method, sources, manufacturer guidance, and customer talking points.
AHow much hot water?▾
Optional — used if higher than beds + baths
Default 10°C for UK
BHow big a cylinder?▾
Leave blank to use calculated minimum.
CHow long to reheat?▾
Lesser of heat generator output at DHW flow temp or coil rating
Cost to reheat
Select what reheats the cylinder and enter the fuel price to see running costs.
Check current Ofgem price cap or homeowner's actual tariff
Select what reheats the cylinder
Between 1.0 and 8.0
Shown on the report
AD L 2021: gas 92%, oil regular 91% (ErP)
Shown on the report
✓Summary▾
+Additional Considerations▾
Outlet hot water use — mixing equation
How much stored hot water does a specific outlet actually use? Enter the outlet details below.
Temperature at the tap/shower
Target reheat time — what P is needed for the entire cylinder?
If the client wants the entire cylinder (V_cyl) reheated within a specific time, this calculates the minimum heat input required.
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References: CIPHE (2025) | CIBSE DHDG (2026) | MCS MIS 3005-D (2025) | BS 8558:2015 | AD L 2021 5.11