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VAV Terminal Reheat Coil Sensible Heat Capacity Calculator

Calculate the sensible heating capacity a VAV terminal's reheat coil must provide for a given airflow and target temperature rise.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-27 · v1.1.0

Market
Imperial · sales tax

Required reheat coil sensible capacity

25917.41 BTU/hr

Check your inputs

This is a simplified sensible-heat sizing check using the standard-air 1.08 factor — it is not a substitute for full manufacturer coil selection, which also accounts for entering water/electric element temperature, coil rows, fin spacing, and actual air density (the 1.08 factor itself shifts at high altitude).

At the values currently entered, the required reheat coil sensible capacity works out to 25917 BTU/hr. Confidence is moderate: the method is sound, but real materials and site conditions vary. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Add the equipment this sizes

This result is a specification — 25,917.408 BTU/hr — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Q(Btu/hr) = 1.08 x CFM x deltaT, the standard ASHRAE sensible heat formula for air at standard conditions (60 min/hr x 0.075 lb/ft3 standard air density x 0.24 Btu/(lb*F) specific heat of air is approximately 1.08). This is a simplified sizing/balance check; full VAV reheat coil selection also accounts for entering water temperature, coil rows, fin spacing, and actual air density at altitude.

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Frequently asked questions

Where does the 1.08 factor come from?
It combines standard air properties: 60 minutes per hour x 0.075 lb/ft3 standard air density x 0.24 Btu/(lb*F) specific heat of air, which multiplies out to approximately 1.08 — the standard ASHRAE sensible heat formula for air at standard conditions.
What airflow should I use for a VAV reheat calculation?
Use the terminal's airflow rate at the reheat condition — typically its minimum (heating) airflow setpoint, since reheat is usually staged in at reduced airflow to avoid overcooling the space.
Is this enough to select an actual reheat coil?
No — this is a simplified sensible-heat sizing check using the standard-air 1.08 factor. Full manufacturer coil selection also accounts for entering water or electric element temperature, coil rows, fin spacing, and actual air density, which shifts the 1.08 factor itself at high altitude.