LEFOO LFH20 Room Temperature & Humidity Transmitter
Indoor temperature and humidity transmitter with 4–20 mA, 0–10 V or Modbus RS485 output options.
Manufacturer: LEFOO
Technical Overview
| Measurement | Humidity and temperature |
|---|---|
| Family / model | LFH20 Room Temperature & Humidity Transmitter |
Official Source
Manufacturer source and technical documentation →
Verify current manufacturer datasheet and exact ordered option before using or specifying this model. A manufacturer family page may cover several hardware configurations.
LFH20 — indoor RH and temperature mapping
LFH20 combines temperature and RH feedback with configurable analog or RS485 interfaces in the manufacturer’s range. Commission the two engineering-unit values separately, checking whether a selected suffix includes the desired 4–20 mA, 0–10 V or Modbus connection. Wall placement away from direct sun, heating devices and cooling discharge materially affects reading representativeness. No standard LFH20 Ex classification should be inferred from related LFH71 models.
LFH20 — separate temperature/RH outputs and supply requirements — engineering details
Hardware output variants, sensor channels and the original maker’s rated operating environment must be matched with the actual supplied part number.
| Technical parameter | Original manufacturer data | Application consequence |
|---|---|---|
| Humidity | 0–100%RH; ±3%RH at 20 °C / 20–80%RH | Accuracy outside reference RH/temperature conditions not guaranteed. |
| Temperature | Digital ±0.3 °C at 20 °C; passive RTD/NTC variants depend on order code | A passive RTD/NTC output is not an active RS485 temperature measurement. |
| Measuring ranges | 0–50 °C or −20 to +60 °C ordered temperature spans | Temperature range and passive sensor class can differ. |
| Signal choices | 0–10 V, 4–20 mA or Modbus RS485, optional LCD | Order RH and temperature output combinations separately. |
| Current-loop compliance | Current variant 9.5–35 V DC unloaded; 19.5–35 V DC for 500 Ω burden | The powered current loop is a different supply condition from voltage/RS485 versions. |
| Voltage/digital supply | 15–35 V DC or 24 V AC; isolated transformer for AC supply | Observe BACnet/Modbus grounding, loop interference and surge protection. |
| Application | Indoor rooms, warehouses, IT rooms; IP30; −20 to +60 °C operational environment | IP30 is not outdoor humidity sensor sealing. |
Commissioning and maintenance
Commission RH and temperature as separate units and actual sensor codes. Direct 4–20 mA input scaling for 0–100% RH is not the same as a passive 10k NTC resistance measurement. A 500 Ω load impacts transmitter supply minimum; undervoltage can cause artificial sensor failures. Avoid placing a wall device near sunlight, supply-air diffusers or heating pipes. In a chemically aggressive storage area sensor exposure may cause long-term RH drift, even with a sensor described as precise.
Original manufacturer source: LEFOO exact model product specifications. Exact variant documentation must govern installation and certification.
AirAlign product-level technical review — 25 October 2026. Independent safety/Ex/product warranty validation still pending.