ENGINEERING TRAININGGuest-room HVAC · Four-pipe fan coil

LOADING 3D MODEL

ENGINEERING TRAINING · GUEST-ROOM HVAC

Inside the Fan Coil Unit

A four-pipe, vertical recessed fan coil — opened up, explained part by part, and brought to life with live airflow and water flow.

01/ 12

TECHNICIAN CHECK

THERMOSTAT · BY ENTRY DOOR

80°

SETPOINT

72°

SATISFIED

MODE

FAN

AUTO FAN WHEN SATISFIED (DEADBAND)

ROOM LOAD (WEATHER & SUN)

SIMULATION SPEED

UNITS

AIR AT UNIT (RETURN)

—

ROOM AVERAGE

—

SUPPLY AIR

—

FAN

—

CHW ACTUATOR (NC)

CLOSED

HW ACTUATOR (NC)

CLOSED

CHW SUPPLY → RETURN

—

HW SUPPLY → RETURN

—

AIRFLOW

0CFM

CONDENSATE PAN

0% full

Sequence of operation: the thermostat by the entry door calls for cooling at 1 °F above setpoint and stays on until it reads 0.5 °F below it; heating starts at 1 °F below and stops at setpoint, so the whole room gets there, not just the air at the unit. After a cooling call ends, heating is locked out for 30 minutes (and vice versa) so the unit never hunts between the two. It energises one normally closed on/off actuator at a time. In Auto, the fan runs Low with the valve call, Medium at 2 °F from setpoint and High at 3.5 °F, dropping back 20 % below each switch point. Values are illustrative; your plant and thermostat settings will differ.

Access doorOpen or close the service door

X-raySee through casing, duct and wall

Fan sled outSlide the fan out for service. Needs the unit service switch OFF first

Bathroom exhaust & make-up airContinuous exhaust above the toilet, fresh air from the grille above the hallway

Corridor door air gapTiny flow under the corridor door toward the exhaust

Temperature tagsLive readings at the unit, mid-room and the thermostat

Floor temperature mapSoft glow on the carpet: blue cooler, red warmer than setpoint

AirflowRoom air → filter → coils → fan → grille

Clear piping (see-through)Shows the branch piping and risers as clear tubes so you can watch the water inside

Water flowChilled and hot water through the coils

EXPLODED VIEW

CAMERA

Tip: drag to orbit, scroll or pinch to zoom, right-drag or two fingers to pan. Tap any part for details.

TRAINER CONTROLS

Set up a fault

Switch faults on, hand over the tablet, and let the trainee find it with the thermostat, the terminal strip and the multimeter. Status shows only what a technician would see.

Hide diagnosticsHide the Simulate readouts and the terminal-strip labels during an exercise

Tip: run at ×120 so a clogged pan trips the float in seconds. The float resets automatically once the water drops below about 60%.

ROOM TEMPERATURE

ON/OFFAUTO
MODEAUTO
FANF/C

Buttons under the screen, left to right: ON/OFF, MODE (Auto → Cool → Heat), FAN (Auto → Low → Med → High), F/C. Arrows change the setpoint (circled). To open the installer menu, hold the left and right buttons together for 10 seconds (on a touch screen, hold both; with a mouse, use the button above).

BREAKER → UNIT SERVICE SWITCH (120 V) → TRANSFORMER 24 V → FLOAT SWITCH → TERMINAL 1 · AND → FAN MOTOR

UNIT TERMINAL STRIP · INSIDE THE ACCESS DOOR · FROM THE THERMOSTAT ↑ · TO THE UNIT ↓

Power: LINE–N ≈ 120 V = breaker on (0 = breaker tripped). L–N ≈ 120 V = service switch on (LINE 120 but L 0 = switch off). FAN–N ≈ 120 V = motor powered on the active speed. 24V–COM ≈ 24 V = transformer good (0 with 120 V in = fuse or transformer). 24 V out but 0 on terminal 1 = float switch open. Strip: meter on V~, black probe on 2 (COM). 1–2 ≈ 24 V = power. 3–2 ≈ 24 V = cooling actuator open (0 = closed). 4–2 ≈ 24 V = heating actuator open. 5 = damper, not used. 6/7/8–2 ≈ 24 V = fan on LOW/MED/HIGH; ≈ 6 V = bias, not running on that speed.

VAC

Pick a probe, then tap a terminal.

Representative four-pipe vertical recessed fan coil. Always confirm against your unit's submittal and nameplate.