For HVAC plants, pump stations and heating substations, a "big PLC" is usually overkill while simple relay logic is not enough. Schneider Electric's Modicon M171/M172 series fills exactly this middle ground.
Modicon M171/M172 series — DIN-rail mounted, with and without built-in display
Key features
Purpose-built for HVAC and pumping — a dedicated engineering environment with ready-made function libraries for heating, cooling and pressure control
Compact with rich I/O — DIN-rail mounted, small panel footprint, display and blind variants
Proven in harsh conditions — years of service in heating substations through Mongolian winters
Affordable — professional-grade automation without buying a large PAC
Real deployment: Darkhan District Heating
We automated heat-distribution centres 7 and 8 in Darkhan on the M172. Pumps, valves and heat exchangers now track outdoor temperature automatically — a stable heating regime and lower operating costs. USUG's pump stations also run on M172.
SCADA display of heat-distribution centre 7: M172-controlled heat exchangers, pumps and VFDs with live values, alarms and trends
As the screen shows, every controller value — pressures, temperatures, pump load, VFD frequency — reaches the SCADA level in real time, enriched with alarms and historical trends. Proof that the M172 is "small but complete".
M171/M172 or M340?
The Modicon family: left — M171/M172 (HVAC, pumping), centre — machine-automation range, right — M340/M580 rack-based PACs
Rule of thumb: single facility, HVAC/pump-level control → M171/M172; multi-node, high-speed or redundant industrial processes → M340 and up (M580 ePAC when Hot Standby is required). Our engineers will determine the right fit for free.
