Enter your project conditions to compare conventional HVAC vs. TRICOIL run-around coil heat recovery.
ℹ How to Use This Calculator
▾
TRICOIL traces the cooling-coil air process on a psychrometric chart and calculates
the room sensible load, latent load, and coil performance. It is designed for single-zone systems
with any mix of outside and return air — from 0 % to 100 % OA.
STEP 1 — Set Outdoor Design Conditions
Type a city name in the Design Location picker and select a design frequency
(0.4 % / 1 % / 2 %). Click Apply to load outdoor dry bulb and wet bulb.
Use Cooling (DB/MWB) for most projects. Switch to
Dehumidification (DP/MCDB) when outside air fraction exceeds roughly
30 % or when latent load governs — labs, hospitals, school gyms, 100 % makeup-air units.
The dew point and mean coincident dry bulb fill automatically from ASHRAE 2017 Table 1;
verify against your project-specific tables before finalizing.
STEP 2 — Enter Airflows and Room Conditions
Enter Outside Air CFM and Return Air CFM
(supply = OA + RA). Set the Room DB and RH % —
75 °F / 50 % is a common starting point. The mixed-air state
(Point A) updates instantly as you type.
STEP 3 — Set Coil Leaving and Supply Air Conditions
Point C is the air leaving the cooling coil — enter DB and WB to match
your coil selection or target ADP. Point D is the supply air delivered
to the room — equal to C for a DX system; slightly warmer for systems with reheat or
fan heat downstream of the coil. Adjust the Coil Efficiency slider to position D
automatically, or drag it on the chart.
Reading the Psychrometric Chart
A — Mixed air entering the coil B — Apparatus dew point (coil process direction) C — Air leaving the coil D — Supply air into the room Room — Design room condition
The D→Room line is the Room Sensible Heat Factor line.
If D lies on the RSHF line through the room point, the coil is
correctly sized for both sensible and latent load simultaneously.
Drag to Explore
Each labeled point on the chart has a dashed-circle drag handle. Grab and drag: C — slides along its constant-RH curve (coil physics); adjusts latent capacity D — moves horizontally (constant humidity ratio); simulates reheat or fan heat Room — repositions the design room condition freely
The Live Load Box (lower-right of the chart) updates in real-time —
Total Cooling (tons), Sensible (MBH), Latent (MBH), and RSHF. Use this to confirm
the coil selection satisfies your load calculation.
Typical Design Workflow
Select location → Apply outdoor conditions
Enter OA CFM, RA CFM, room DB & RH
Set Point C to match coil leaving conditions
Scroll below the chart → press ▶ Calculate Performance
Confirm D→Room RSHF line aligns with room load
Check Live Load Box — Total & Latent satisfy load calcs
If latent governs, switch to Dehumidification design and repeat
All psychrometric calculations use ASHRAE IP equations at standard atmospheric pressure (14.696 psia / sea level).
Results are for design verification — always cross-check against coil manufacturer's certified data.
Design Location — ASHRAE 2017 Outdoor Conditions
DEHUMIDIFICATION DESIGN — Use when latent load governs: labs, hospitals, 100% makeup air, high-OA fraction systems.
Values pre-filled from ASHRAE 2017 Table 1 (approximate — verify against your project tables before finalizing).
WB computed from DP + MCDB
Cooling Season Inputs
Point A — Mixed Entering Air (Calculated)
Outside Air
Room Return Air
↓ mixed entering air ↓
—
Dry Bulb (°F)
—
Wet Bulb (°F)
—
Rel. Humidity (%)
—
Total CFM
Point C — Primary Coil Leaving
Point D — Reheat Leaving / Supply
TD = TC + ε × (TA − TC) |
Higher efficiency requires more coil surface area. 45% is the practical maximum.
Point E — Supply Air (After Fan)
TE = TD + fan heat rise | W unchanged through fan.
Heating Season Inputs
Outside Air Dry Bulb auto-fills from the city selected above in Design Location, at the Design % chosen here. You can still overwrite it manually for a specific project.
Psychrometric Chart
▶
Press the Calculate Performance button to populate this chart
Scroll below this chart and click ▶ Calculate Performance.
Point A updates as you type — the full A→B→C→D process path and load results require Calculate.
↓
Psychrometric States — Cooling Season
Property
A — Mixed Entering
B — After Precool
C — After Primary Coil
D — After Reheat
E — Supply (After Fan)
Performance Comparison
Cooling Season
Value
Unit
Heating Season
Value
Unit
Takeaway Summary
Calculate performance first to generate the takeaway.
