Customer
Our client is a French company specialising in the design and manufacture of thermal comfort solutions and is the market leader in Europe.
Tested product
Mechanical thermostat
Mechanical thermostats are devices for temperature control of automated systems. They establish or not a contact when the measured temperature exceeds a threshold.
Objective
Check the temperature thresholds on several thermostats simultaneously when the temperature rises and falls.
Problematic issues
The bench must be able to control up to 10 thermostats at the same time and the hydraulic circuit must be closed loop. The system shall be able to set optimised temperature ramps, smooth enough to obtain an accurate measurement of the switchover temperature and fast enough to allow rapid testing of the thermostats over a large number of cycles.
Solution and result
The LF Technologies teams have designed a cyclic temperature test loop that can control the heating or cooling ramps of 10 mechanical thermostats simultaneously. The bench performs tests according to the NF EN 257 standard (Mechanical thermostats for gas appliances). This bench allows the operator to carry out a series of programmable cycles via a PC, on which the switching values of the thermostats are automatically archived in the form of an exploitable Excel spreadsheet.
The software will also list the faults identified during the test (edges, temperature ranges out of tolerance, etc.).
The hydraulic circuit, pressurised to about 1 bar, contains a very small volume of water (≈ 3 l.) to optimise thermal inertia, and a circulator is present in the circuit to ensure temperature homogeneity. A heater provides heating, while a heat exchanger and a chiller provide cooling for the test loop. The closed circuit has the advantage of avoiding any hot water splashes.
The cyclic temperature test loop can also be used to control and test electronic thermostats or PT 100 temperature sensors.
