Systemair
SAVE Heat Recovery Ventilation for Energy-Efficient Buildings
Systemair (Skinnskatteberg, Sweden) is a leading European HVAC manufacturer — the SAVE series heat recovery ventilation (HRV) units are widely used in Scandinavian, German, and Dutch energy-efficient buildings (Passive House, BREEAM Excellent). Modbus RTU interface enables straightforward KNX building automation integration.
Role in our panels
How we use Systemair
SAVE VTC 700 M (commercial, 700 m³/h): Modbus RTU on RS485 (9600 baud, 8N1, unit ID 1). Registers: 4001 (supply fan speed, rpm, read), 4002 (extract fan speed, rpm, read), 4003 (supply air temperature, 0.1°C), 4004 (extract air temperature, 0.1°C), 4005 (outdoor air temperature, 0.1°C), 4006 (exhaust air temperature, 0.1°C), 4007 (operation mode, read/write: 0=off, 1=auto, 2=manual speed 1, 3=speed 2, 4=speed 3/boost), 4010 (boost mode enable, write: 0=normal, 1=boost), 4016 (heat recovery efficiency, %). SAVE VSR 300 HRV (residential, 300 m³/h): same Modbus map, unit ID 1. KNX integration: MDT Modbus Gateway polls SAVE every 30s for temperatures, 10s for fan mode. KNX group objects: DPT 9.001 for temperatures, DPT 5.001 for fan speed (%), DPT 1.001 for boost trigger. KNX CO2 sensor (Elsner KNX CO2-T-UP): when CO2 > 1000 ppm (DPT 9.008 threshold in KNX logic block), write Modbus reg 4007 = 4 (boost). SYSCONTROL: optional Systemair BMS module for IP-based control — alternative integration path via REST API for systems without Modbus gateway.
Systemair SAVE HRV units communicate via Modbus RTU — KNX Modbus gateway reads temperatures and fan status, and writes operation mode and boost commands for CO2-triggered demand-controlled ventilation.
Used in these project types
Systemair products
Key components we install
SAVE VTC 700 M commercial HRV
Commercial 700 m³/h heat recovery unit with Modbus RTU for KNX building automation integration
SAVE VSR 300 residential HRV
Residential 300 m³/h balanced ventilation with heat recovery and Modbus RTU interface
SAVE VSRA 500 premium HRV
Premium residential HRV with integrated electronic control panel and Modbus RTU
VHR residential balanced ventilation unit
Compact residential balanced ventilation with heat recovery for apartments and smaller homes
Systemair FAQ
What is the Modbus unit ID on SAVE units?
Default is 1. Check the SAVE service menu (hold arrow button 5 seconds) to confirm or change the unit ID if multiple units share the same RS485 bus.
Can KNX control SAVE fan speed directly?
Yes — write Modbus reg 4007 (values 0-4 for off/auto/speed1/speed2/speed3-boost) from a KNX Modbus gateway to control fan speed from KNX group telegrams.
What is the maximum RS485 bus length?
1000m for Modbus RTU at 9600 baud — sufficient for most building installations including rooftop-to-panel runs.
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