How do I calculate supply air temperature after heat recovery?

Enter outdoor air temperature, extract air temperature, and heat exchanger efficiency. Supply temperature = T_outdoor + ε × (T_extract − T_outdoor).

What efficiency should I use for MVHR?

Use the manufacturer's certified sensible efficiency at design flow and frost conditions — not brochure peak figures.

How does frost protection affect winter supply temperature?

Below ~−4°C many units defrost or pre-heat, reducing effective recovery. Check the unit's cold-weather performance data.

BuildFlo Design Guide · Ventilation · CIBSE / AM13

Heat recovery supply air temperature calculator

Calculate MVHR/HRV supply air temperature from heat exchanger efficiency. Free heat recovery temperature calculator.

What this calculator does

Heat recovery temp helps UK building services engineers with mvhr / hrv supply temperature, required η, or reheat duty from efficiency and air temperatures. The calculation follows CIBSE / AM13 methods used in everyday MEP design — enter your project inputs below for a first-pass result.

Whether you searched for "heat recovery temp", "heat recovery temp calculator", or "how to heat recovery temp", this page gives you a working tool plus the context to use it on a real job.

When to use it

Use this for early-stage sizing and sanity checks on UK building services work. It is not a substitute for issued calculations — verify against the project specification, drawings, and relevant standard before sign-off.

How to use it

1. Fill in the inputs for your scenario (defaults are starting points only). 2. Click Calculate — results include the method and assumptions where applicable. 3. Verify against the project specification and relevant standard before issuing.

Typical output unit: °C.

Tips

Defaults are indicative — replace with project-specific values from the architect, structural, or MEP spec.
For issued calculations, save results in your BuildFlo project and attach to the calculation folder.
Need the regulation citation? Open BuildFlo chat in the app and ask about heat recovery temp under UK standards.

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Frequently asked questions

How do I calculate supply air temperature after heat recovery?: Enter outdoor air temperature, extract air temperature, and heat exchanger efficiency. Supply temperature = T_outdoor + ε × (T_extract − T_outdoor).
What efficiency should I use for MVHR?: Use the manufacturer's certified sensible efficiency at design flow and frost conditions — not brochure peak figures.
How does frost protection affect winter supply temperature?: Below ~−4°C many units defrost or pre-heat, reducing effective recovery. Check the unit's cold-weather performance data.