# Water Heater Storage and Recovery Calculator — Ireland

> Relate a specified mixed-water draw to ideal storage and recovery power using an explicit temperature balance. EUR planning view; stated limitations apply.

Page: https://askcalculators.com/ie/water-heater-sizing/
Definition: https://askcalculators.com/ie/water-heater-sizing/definition.json
JSON Schema: https://askcalculators.com/ie/water-heater-sizing/schema.json
Version: 20.16.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/ie/water-heater-sizing/?unitSystem=metric&peakLitres=150&coldTemp=10&deliveryTemp=40&storageTemp=60&recoveryHours=2&efficiency=90&unitRate=0&laborCost=0&deliveryCost=0&otherCost=0&costMultiplier=1&spreadPercent=15&taxRate=0

## Inputs
- unitSystem: Measurement system; type=select; optional; default=metric; values=imperial|metric
- peakLitres: Mixed hot-water draw in the design period; type=number; required; default=150; min=0; max=1000000000000
- coldTemp: Cold inlet temperature; type=number; required; default=10; min=-5; max=50
- deliveryTemp: Required mixed delivery temperature; type=number; required; default=40; min=0; max=80
- storageTemp: Specified storage temperature; type=number; required; default=60; min=0; max=100
- recoveryHours: Allowed recovery period, hours; type=number; required; default=2; min=0.01; max=48
- efficiency: Recovery input-to-water efficiency; type=percent; required; default=90; min=0; max=100
- unitRate: Material price per quoted water-heater project; type=money; required; default=0; min=0; max=1000000000000
- laborCost: Total labor allowance; type=money; required; default=0; min=0; max=1000000000000
- deliveryCost: Delivery allowance; type=money; required; default=0; min=0; max=1000000000000
- otherCost: Other fixed costs; type=money; required; default=0; min=0; max=1000000000000
- costMultiplier: Material/labor multiplier; type=number; required; default=1; min=0.1; max=10
- spreadPercent: Low/high sensitivity around the entered total; type=percent; required; default=15; min=0; max=100
- taxRate: Explicit tax allowance; type=percent; required; default=0; min=0; max=100

## Outputs
- storedLitres: Ideal usable hot-water storage; format=number
- usefulKwh: Useful recovery heat, kWh; format=number
- inputKw: Required input power, kW; format=number
- materialCost: Material cost; format=currency
- laborCost: Labor allowance; format=currency
- deliveryCost: Delivery allowance; format=currency
- otherCost: Other specified costs; format=currency
- tax: Entered tax allowance; format=currency
- low: Low cost scenario; format=currency
- mid: Middle cost scenario; format=currency; primary
- high: High cost scenario; format=currency

## Formula
ideal stored volume = mixed draw × (delivery − cold) ÷ (storage − cold); useful kWh = mixed litres × 4.186 × (delivery − cold)/3,600.

Inputs are converted to canonical units before evaluating this stated formula.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: Illustrative defaults are not local quotes or verified legal rules. Dated reference components and user-entered assumptions are explicitly distinguished. Professional review is pending.