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Hydronic BTU / GPM / ΔT

Solve for any one from the other two. The quickest sanity check on whether a coil is actually doing its job.

Free tool · BAS Field Fundamentals

Works offline. Every calculation runs on your device, no signal needed. Install the BAS Field Reference app to keep it on your phone.

How to use it

  1. Measure supply and return water temperature and the flow rate.
  2. Leave the field you want calculated blank, or just change the other two.
  3. A coil showing good flow and almost no ΔT is usually a valve passing when it should be closed, or a coil that is fouled.
  4. For glycol mixes, set the fluid factor — water is 500, and glycol carries less heat per gallon.

Background reading: Chapter 1 — reading points in context →

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More where this came from

This calculator comes out of BAS Field Fundamentals — the meter tests, the maths and the failure modes for every sensor, drive and control loop in the building, plus 20 field cases and a browser simulator to practice on.

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