Solution - HVAC with Blower Speed
Description
HVAC with Blower Speed Control
HVAC with blower speed control covers heating, ventilation and air conditioning units where the fan operates at several fixed speeds.
The PIERRE Controller manages the HVAC unit based on the measured room temperature. Each controller output is connected to a relay, and each relay controls a specific HVAC function, such as unit ON/OFF switching or selecting the required blower speed.
The Controller determines the required operating state and activates the corresponding relay outputs to switch the HVAC unit and select the appropriate fan speed.
Configuration
To add an HVAC unit with blower speed control:
- Open the desired Controller.
- Navigate to Outputs.
- Assign one Controller output connected to a relay for switching the HVAC unit ON/OFF.
- Assign one Controller output connected to a relay for each supported blower speed.
- Select the temperature sensor used for measuring the room temperature.
- Configure:
- Name
- Role
- Image
- Submit and save the configuration.
Blower Speeds
Each blower speed requires a separate Controller output connected to a relay.
For example, a three-speed HVAC unit requires:
- one output + relay for ON/OFF control,
- one output + relay for low speed,
- one output + relay for medium speed,
- one output + relay for high speed.
Only one blower speed relay should be active at the same time. Always verify the correct wiring method and switching requirements in the HVAC unit manufacturer's documentation.
Covered Equipment
This configuration can be used with any HVAC equipment that supports external switching of the ON/OFF state and blower speed selection.
Typical applications include:
- fan coil units,
- air conditioning units,
- ventilation units,
- heating and cooling units with multi-speed fans.
The important requirement is that the HVAC unit accepts external relay-based control for power switching and fan speed selection.
Automation Applications
Examples of possible automation scenarios:
- Running the HVAC unit only when the room temperature differs from the target temperature.
- Limiting the HVAC unit to the lowest blower speed during nighttime.
- Stopping the unit when a door or window contact detects that it is open.
- Automatically selecting the required fan speed based on heating or cooling demand.
Technical Notes
- Each HVAC function requires a separate Controller output connected to a relay.
- The number of required outputs depends on the number of available blower speeds.
- A temperature sensor configured on the same Controller is required for temperature-based regulation.
- The HVAC unit's own control panel may need to be configured for external control mode.
- Verify that the relay contact rating is suitable for the connected HVAC control circuit.
- The relay outputs are used for switching the HVAC control signals and must be wired according to the HVAC manufacturer's documentation and the PIERRE wiring diagram.
Schemes
HVAC with blower speed - Electric schemes
Cables
| Position | Wires | Diameter | Type | Comment |
|---|---|---|---|---|
| From relay to HVAC with blower speed | 6 | 1.5 mm² | NYM-O | valve |
| DC and Signal | 5 | 0.75 mm² | H07V-K | VALVE, SPEED 1, SPEED 2, SPEED 3, N, PE |
| From Temperature sensor to PIERRE | 3 | cat.5 | UTP | +5V, GND, SIGNAL |
FAQ
If the power goes out, smart devices will retain their last state and resume functionality when power is restored. For critical devices, battery backups can be used to maintain operation during an outage.
No, a classic thermostat is not necessary. Instead, a temperature sensor integrated with the PIERRE system can monitor the room’s temperature and manage the heating/cooling devices accordingly.
Yes, PIERRE offers its own smart thermostats, which can be found in the thermostat product category.
Yes, you can replace an old thermostat with a PIERRE display, as long as the display includes a temperature sensor for temperature monitoring.
Heat meters with an M-Bus interface are read through an Intesis M-Bus to Modbus gateway connected to a PIERRE Pro controller. The meters are wired to the gateway's M-Bus (a shared two-wire bus) and the controller reads them over Modbus RTU.
Yes, you can control the temperature room by room.
The circulation pump’s operation is based on automation, so if the valve in any apartment’s floor heating system is activated, it simultaneously activates the circulation pump. If separate control is needed, it can only be handled locally within the apartment.
Each apartment measures its own temperature and humidity and controls the valves on its distribution manifold. The circulation pump of the floor (or of the building) is switched on by automation whenever any manifold valve on that floor is open, and off again when all valves are closed.
Yes, per manifold: an automation opens the valve when the room temperature drops below the set point and starts the pump once the valve is open (or after a short delay).
The heat pump can be controlled by PIERRE in two ways: • Potential-free contacts: one contact switches winter/summer mode, another starts and stops the heat pump. • Modbus RTU: consult the manufacturer or distributor in advance about the Modbus register addresses and documentation for the heat pump model.
The motorized valves for underfloor heating zones can be controlled without any issues by the PIERRE system, whether they are On-Off or 0-10V valves. In the mechanical room, the PIERRE system handles the following controls: winter-summer mode switching via a potential-free contact, circulation pump control, hot water circulation pump control, and 0-10V mixing valve control with supply water temperature measurement.
