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Heat Pump Sizing Calculator — Ireland

Translate an already assessed design load into a manufacturer-rating requirement at the local cold-weather performance point. EUR planning view; stated limitations apply.

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Inputs

Enter the values you know. Optional fields may be left empty.

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Optional
Required
kW thermal
Required
kW thermal
Required
%
Required
%
Required
EUR
Required
EUR
Required
EUR
Required
EUR
Required
Required
%
Required
%

Result

Updates as valid inputs change.

Calculated locally
Illustrative defaults are not local quotes or verified legal rules. Dated reference components and user-entered assumptions are explicitly distinguished. Professional review is pending.
Required rated heating capacity
—
Larger heating/cooling capacity requirement
—
Cooling-equivalent refrigeration tons
—
Material cost
—
Labor allowance
—
Delivery allowance
—
Other specified costs
—
Entered tax allowance
—
Low cost scenario
—
Middle cost scenario
—
High cost scenario
—

Saved locally, explained clearly

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Calculation steps

Follow what happened from the selected formula to the displayed answer.

Show substituted values and intermediate working
Calculate current inputs to see the working.
  1. 1

    Formula selected

    The calculator uses the following formula or method.

    rated heating capacity = design heat loss × (1 + allowance) ÷ capacity retained at design temperature.

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

  2. 2

    Values entered

    Your values are placed into the calculation.

    Enter values to see what is used in this step.

  3. 3

    Result calculated

    The formula or method produces the following result values.

    Results will appear after a successful calculation.

  4. 4

    Answer formatted

    Displayed values are rounded and formatted using each output’s configured precision.

Scenario comparison

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Data and privacy

How it works

Translate an already assessed design load into a manufacturer-rating requirement at the local cold-weather performance point.

This is the Ireland planning view, with monetary inputs and outputs in EUR. A currency label does not establish that a tax rate, construction price, coverage rule or legal limit has been verified locally. The inputs and limitations below describe the actual scope.

Input query strings and outputs

Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.

Input query strings

12
  • ?unitSystem= Measurement system

    Choice · Optional · Default: metric · Accepted values: imperial, metric

  • ?designHeatLoss= Professionally assessed design heat loss

    Number · Required · Default: 8

  • ?coolingLoad= Assessed design cooling load

    Number · Required · Default: 4

  • ?coldCapacityRetention= Rated heating capacity retained at local design temperature

    Percentage · Required · Default: 75

  • ?designMargin= Explicit design allowance

    Percentage · Required · Default: 5

  • ?unitRate= Material price per kW of rated thermal capacity

    Money · Required · Default: 0

  • ?laborCost= Total labor allowance

    Money · Required · Default: 0

  • ?deliveryCost= Delivery allowance

    Money · Required · Default: 0

  • ?otherCost= Other fixed costs

    Money · Required · Default: 0

  • ?costMultiplier= Material/labor multiplier

    Number · Required · Default: 1

  • ?spreadPercent= Low/high sensitivity around the entered total

    Percentage · Required · Default: 15

  • ?taxRate= Explicit tax allowance

    Percentage · Required · Default: 0

Outputs

11
  • requiredKw Required rated heating capacity

    Number · Primary output

  • selectedKw Larger heating/cooling capacity requirement

    Number

  • tons Cooling-equivalent refrigeration tons

    Number

  • materialCost Material cost

    Currency · Currency: EUR

  • laborCost Labor allowance

    Currency · Currency: EUR

  • deliveryCost Delivery allowance

    Currency · Currency: EUR

  • otherCost Other specified costs

    Currency · Currency: EUR

  • tax Entered tax allowance

    Currency · Currency: EUR

  • low Low cost scenario

    Currency · Currency: EUR

  • mid Middle cost scenario

    Currency · Primary output · Currency: EUR

  • high High cost scenario

    Currency · Currency: EUR

Formula

rated heating capacity = design heat loss × (1 + allowance) ÷ capacity retained at design temperature.

Calculations retain numeric precision internally. Displayed values are rounded for readability. Quantities that must be purchased as whole units are rounded up only where the formula explicitly requires it.

Read the inputs before calculating

  • Professionally assessed design heat loss: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
  • Assessed design cooling load: Enter the quantity described by the label. The measurement selector converts this physical quantity; it does not change the underlying scenario.
  • Rated heating capacity retained at local design temperature: Enter the quantity described by the label.
  • Explicit design allowance: Enter the quantity described by the label.
  • Material price per kW of rated thermal capacity: Zero means unpriced, not free. Enter a current, scoped supplier quote.
  • Total labor allowance: Enter the quantity described by the label.
  • Delivery allowance: Enter the quantity described by the label.
  • Other fixed costs: Enter the quantity described by the label.
  • Material/labor multiplier: Use a verified regional index only when supplied. 1 is an unadjusted scenario, not a researched index.
  • Low/high sensitivity around the entered total: Enter the quantity described by the label.
  • Explicit tax allowance: Enter the quantity described by the label.

Reproducible worked example

The following is a fictional arithmetic example, not a local quote, a verified claimant or a market forecast. Its values are included so the formula can be checked. The form does not automatically confirm any verification checkbox.

InputExample value
Professionally assessed design heat loss (kW thermal)8
Assessed design cooling load (kW thermal)4
Rated heating capacity retained at local design temperature75
Explicit design allowance5
Material price per kW of rated thermal capacity0
Total labor allowance0
Delivery allowance0
Other fixed costs0
Material/labor multiplier1
Low/high sensitivity around the entered total15
Explicit tax allowance0
OutputCalculated result
Required rated heating capacity11.2 kW thermal
Larger heating/cooling capacity requirement11.2 kW thermal
Cooling-equivalent refrigeration tons3.1847
Material costEUR 0
Labor allowanceEUR 0
Delivery allowanceEUR 0
Other specified costsEUR 0
Entered tax allowanceEUR 0
Low cost scenarioEUR 0
Middle cost scenarioEUR 0
High cost scenarioEUR 0

Interpreting a changed assumption

Start with one complete scenario and change only one input when diagnosing a difference. Recheck units, the period of every rate, whether an amount is recurring or one-off, and whether a cost is already included elsewhere. A larger calculated benefit is not evidence that an assumption is more likely to occur.

Limitations

  • Material is unpriced. A zero material price is not evidence that the material is free.
  • Prices and the tax allowance are user-entered planning assumptions, not a verified local quote. Low/high outputs are sensitivity scenarios, not market confidence limits.
  • The multiplier applies only to material and labor; delivery and fixed costs are not multiplied.
  • Cost is priced per kW of rated thermal capacity in either unit system. A supplier must verify actual model capacity, defrost, backup heat, minimum modulation and refrigerant/electrical requirements.

Frequently asked questions

What does this Heat Pump Sizing result represent?

Translate an already assessed design load into a manufacturer-rating requirement at the local cold-weather performance point. It applies the displayed formula to your inputs; it does not infer omitted facts.

No. Numeric defaults are illustrative unless an input or dated reference explicitly identifies a researched component. Currency is EUR; local quotes, eligibility and unsupported rules must be entered and verified separately.

What must I check before relying on the result?

Check the input units, supplier or authority evidence, the stated model exclusions and the period used for costs. This arithmetic does not supply missing site-specific design or local legal rules.

Can I compare or share different assumptions?

Change one assumption at a time and use the browser-local project or share controls. A shared URL contains the encoded input values; do not include information you do not wish to disclose.

Sources and reference scope

  • DOE energy-use arithmetic — retrieved 2026-09-24. Energy consumption versus power; not a local tariff or an approval of this implementation.
  • PVWatts: site-specific solar estimation — retrieved 2026-09-24. External site-yield model. AskCalculators uses your entered yield; it does not call or reproduce PVWatts.
  • DOE insulation overview — retrieved 2026-09-24. Insulation and thermal resistance concepts; not structural or code approval.

These references support only their stated scope. They are not evidence that every local rule or price needed by the master expansion has been loaded.

Sources
Limitations
  • Illustrative defaults are not local quotes or verified legal rules. Dated reference components and user-entered assumptions are explicitly distinguished. Professional review is pending.
  • Inputs are converted to canonical units before evaluating this stated formula.
  • Material quantities are estimates. Confirm site dimensions, product coverage, waste, and local requirements before ordering or construction.
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