BuildFlo Design Guide · Ventilation · BS EN 378
Refrigerant charge limit calculator
Check maximum refrigerant charge and minimum room volume per BS EN 378. Free calculator for split systems and VRF installations.
What this calculator does
Refrigerant charge limit helps UK building services engineers with maximum charge and minimum room volume per bs en 378. The calculation follows BS EN 378 methods used in everyday MEP design — enter your project inputs below for a first-pass result.
Whether you searched for "refrigerant charge limit", "refrigerant charge limit calculator", or "how to refrigerant charge limit", 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: kg.
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 refrigerant charge limit under UK standards.
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Frequently asked questions
- What is the maximum refrigerant charge for a room?
- BS EN 378 sets charge limits based on refrigerant type, room volume, and floor area. Enter the refrigerant, charge, and room dimensions to check compliance.
- Do A2L refrigerants like R32 have different limits?
- Yes. Flammability classification changes the allowable charge density. Always use the current BS EN 378 tables for the specific refrigerant.
- What if the room is too small for the charge?
- Increase room volume (dedicated plant room), reduce charge (multi-split with smaller circuits), or apply engineered mitigation per the standard.
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