Controls laboratory
Boiler Plant Simulator
Two modulating boilers, a low-loss header and a secondary heating loop. Explore temperature control, staging and pump DP response.
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Water-side system
PRIMARY · BOILERS & DEDICATED PUMPS
Boiler outlets → primary supply → LLH
LLH return → boiler pumps → boilers
Primary flow —
Primary flow —
LOW-LOSS HEADER
Primary supply →—
LLH↔
→ HWS sensor—
← Primary return—
← HWR sensor—
—
Separate pumps, shared water. Arrow shows net internal bypass.
SECONDARY · CIRCULATION & LOAD
LLH hot outlet → circulation pump → HWS sensor
◉ —Flow —Load-circuit DP —DP SP —HWS SP —HWS − HWR —
↓ Load valve / heating load ↓
HWR sensor → LLH cool inlet
Requested load—
Delivered heat—
Unmet load—
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Trend log · select tags
Separate temperature, flow, pressure, percentage and heat axes. HWS sensor failure or no flow leaves a gap in measured HWS.
Loop diagnostics and staging timers
Event log
Latest 100 events · simulated time
Sequence, example scenarios & model assumptions
HWS_CO uses secondary HWS after LLH mixing to request heat. DP_CO controls only the secondary pump. PI gains use the displayed canonical °C/kPa units even when the input/display temperature or pressure unit changes. A zero integral gain gives biased P control. These are conventional PI loops using the documented simulator equations.
Start with 60 kW and Manual HWS SP 60°C. Increase demand to 150 kW to observe lag staging. Select Timed load scenario to apply 30 → 150 → 20 kW at the configured times. Changing to Manual demand overrides the schedule. Load-valve opening is an independent hydraulic disturbance.
Primary pumps follow their boilers and post-run. A boiler needs branch flow, valid secondary HWS feedback and run proof before firing. Minimum modulation and cycling differential can produce low-load cycling. Faults and plant/individual Off override normal minimum-run holds; Manual modulation still respects minimum off and modeled inhibits.
Restore injected faults, Apply settings, then Reset alarms. The HWS sensor alarm also requires reset after signal restoration. High-temperature reset is accepted only after the local outlet cools below its reset threshold. Pump post-run still operates while heat is inhibited.
Two identical boiler teaching models, ideal branch check valves, negligible LLH pressure loss, constant water properties, lumped boiler/loop thermal storage and a bounded aggregate heat sink. LLH mixing follows actual primary/secondary flows; no fixed HWS/HWR temperature difference is assumed. Burner combustion, fuel efficiency, DHW, freeze protection and manufacturer safeguards are outside this model.
Detailed sequence, equations and limitations