HVAC Equipment and Components

This is the hardware that moves the heat: cooling towers, boilers and furnaces, heat exchangers, condensers and evaporators (chillers and heat pumps), pumps/compressors/fans, coils, and energy-recovery devices. It's the single heaviest area on the HVAC & Refrigeration depth — the real problems run tough and the breadth is wide.

What the problems look like

Almost all calculation, and almost all performance: rate, size, or select a piece of equipment against a duty. The recurring shapes — heat-exchanger duty by LMTD or ε-NTU; a pump or fan operating point, power, and affinity-law scaling; cooling-tower range/approach and makeup water; a coil load split into sensible and latent; chiller/heat-pump COP and kW/ton. Expect multi-step problems (find a flow or ΔT → a duty → a power) and lots of curves and performance tables to read — with extraneous data mixed in.

By exam day you should be able to —

• size or rate a heat exchanger with LMTD and ε-NTU, and pick the right method for the data you're given (unknown outlet temps → NTU; counterflow vs. parallel-flow LMTD);
• find a pump's or fan's operating point on its curve, compute hydraulic vs. brake power, and scale flow/head/power with the affinity laws;
• compute cooling-tower range and approach and estimate makeup (evaporation + drift + blowdown, via cycles of concentration);
• compute a coil's sensible, latent, and total capacity from entering/leaving conditions;
• move between COP, kW/ton, and EER, and compute condenser heat rejection / evaporator load.

Where people lose points

• Using LMTD when outlet temps are unknown (needs ε-NTU), or grabbing the parallel-flow ΔT for a counterflow unit.
• ε-NTU with the wrong capacity rate — q = ε·C_min·(T_h,in − T_c,in); using C_max or the wrong stream.
• Confusing brake power with hydraulic power (divide by efficiency); forgetting fan power scales with the cube of speed (flow ∝ N, head ∝ N², power ∝ N³).
• Cooling-tower makeup: ignoring blowdown / cycles of concentration, or swapping range (hot−cold water) for approach (cold water − wet-bulb).
• Sizing tower/condenser duty off the cooling tons alone — a water-cooled condenser rejects the evaporator load plus the compressor work (≈1.25×).
• Dropping the latent term on a coil that's dehumidifying; using a dry-bulb-only ΔT.
• Boiler/furnace fuel input = output ÷ efficiency (multiplying instead of dividing).
• Chiller metrics backwards (lower kW/ton is better, higher COP is better; COP = 3.516/(kW/ton)) and unit slips (12,000 Btu/h per ton).

Have these at your fingertips

Know where the LMTD/ε-NTU, affinity-law, coil/psychrometric, and refrigeration-performance relations sit in the Handbook so you're navigating, not hunting under time. Keep the conversions reflexive: ton ↔ Btu/h ↔ kW, gpm × ΔT × 500 → Btu/h (water), cfm × ΔT × 1.10 → Btu/h (sensible air).

Going deeper

• Heat exchangers — LMTD & ε-NTU
• Pumps, fans & NPSH

Part of the HVAC & Refrigeration depth. Practice this area with exam-real problems — the tutor walks any one you miss. → Start your 7-day free trial — no card. Or take the free practice exam first.