This application focuses on the integration of dual-parameter sensing within groundwater heat pump (GWHP) systems. It details the technical requirements for monitoring aquifer drawdown and source water temperature to maintain thermal efficiency and protect high-value submersible pumping assets.
- Integrated Dual-Output Sensing: Simultaneous measurement of hydrostatic level and Pt100 temperature within a single 26.5 mm submersible housing.
- Regulatory Compliance: Construction materials certified to DVGW W 270 and UBA KTW standards for potable water safety.
- Signal Integrity: Dual 4-20mA analog loops designed for high noise immunity over extended 65-meter cable runs to central heating plant controllers.
- Asset Protection: Real-time level monitoring to prevent pump cavitation and dry-running in narrow borehole installations.
Efficient operation of open-loop geothermal systems, specifically groundwater heat pumps, relies heavily on the precise monitoring of the “source-side” hydrology. In this application, three separate extraction wells reaching depths of 35 meters require constant surveillance to ensure the sustainability of the heat exchange process. The primary challenge involves managing the fluid dynamics within a narrow borehole where space is shared between the riser pipe, the submersible pump, and power cabling. By monitoring the hydrostatic head, the system can prevent dry-running conditions that lead to pump cavitation and premature motor failure. Simultaneously, tracking the temperature of the incoming aquifer water is critical for calculating the thermal delta across the heat exchanger, ensuring the system operates within its designed coefficient of performance and detecting potential thermal breakthrough or freezing risks.
Integrating measurement instrumentation into these environments requires a focus on mechanical footprint and signal stability. Using the LMP307T dual-function transmitter allows for the consolidation of level and temperature data into a single instrument body with a diameter of only 26.5 mm. This slim profile is particularly advantageous in deep-well casings where cable nesting and entanglement can occur during installation or maintenance. Because the heating plant’s control architecture is located up to 30 meters away from the wellhead, the total cable run for each sensor reaches approximately 65 meters. Utilizing 4-20mA analog current loops ensures that the signal remains robust against electromagnetic interference over these distances, providing a reliable feed to the plant’s PLC or building management system without the voltage drop issues associated with other signal types.
For groundwater applications, material compatibility is not merely a matter of longevity but also of regulatory compliance. Since these wells interact with local aquifers, all media-wetted components must adhere to strict drinking water standards. The selection of 316L stainless steel for the housing and diaphragm, combined with EPDM seals, ensures the LMP307T probe does not leach contaminants into the water supply. Furthermore, the use of TPE-U cable jackets provides the necessary durability for long-term submersion while meeting DVGW W 270 and UBA KTW certifications. This technical approach simplifies the installation by reducing the number of individual probes required per well, lowering the risk of mechanical interference with the submersible pump, and providing a high-resolution data stream essential for the automated management of geothermal energy resources.
LMP307T Groundwater Dual Level and Temperature Transmitter Probe
- Part No: 456-4001-000×30-1-1-1-1-3T-3-F-065-000
- Sensor Type: Level and Temperature
- Level Sensing Range: 0 to 40 mH2O
- Reference Type: Gauge / Vented (atm to +P)
- Temperature Sensing Range: 0-30C / 32-86F
- Output Signal: 4-20mA, 2 wire
- Accuracy: 0.35%FS above, 0.5% FS below 4mH2O (11-12bit res)
- Installation Type: Submersible probe with flush diaphragm and detachable nose cone
- Housing Material: Stainless Steel 316L
- Diaphragm Material: Stainless Steel 316L
- Media Exposed Seals: EPDM
- Cable Type: TPE-U (70degC max)
- Cable Length: 65
- Cable Length Units: Metres (m)
- Optional Extras: Drinking water certificate (DVGW W 270 / UBA KTW)