Control Transformer VA Calculator

Add the current of every coil, valve and control on the secondary.

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Formula

VA = V × I

Example calculation

24 V × 1.6 A = 38.4 VA → 40 VA transformer.

Practical HVAC use

Prevent blown fuses and overheated transformers when adding accessories like humidifiers or zoning.

Common mistakes

Ignoring inrush VA of contactors and zone valves.

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