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Load Calc Guru is an online calculator for HVAC contractors to perform residential Manual J load calculations and Manual S equipment verification, producing room-by-room loads and branded reports for bids, permits, and homeowner communication. It offers free unlimited basic Manual J calculations with smart defaults, plus a Pro plan that unlocks advanced inputs, blower door integration, custom design conditions, duct losses, branded PDFs, and full Manual S checks—accessible to start without a credit card. The tool uses ACCA Manual J methodology, accounting for envelope, windows, infiltration, internal gains, and climate design temps to size equipment and ductwork, unifying J, S, and (coming soon) D workflows for a complete design-to-commission process.
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