The energy transition requires efficient space heating appliances. In that context, it is common that thermodynamics laboratories are asked to conduct experimental investigations on those appliances to establish or verify their performance. This paper aims to offer and report an example of a very simple test rig that allows for controlling both the space heating water flow rate and the space heating return temperature. Space heating depart temperature thus depends on those two controlled parameters as well as the heat transfer rate provided by the space heating appliance, based on its settings. The test rig described in this paper has been used to conduct experimental studies on residential Solid Oxide Fuel Cells used as micro-cogeneration units. It has the advantage of being reproductible or reused with other residential space heating appliances. It can easily be adapted for refrigeration appliances testing or even heat exchanger characterization Also, the test rig controlling the space heating flow rate and working temperature implies an approximative cost of only about 1 k€ (with 2021 hardware prices, without the space heating appliance to be tested).