The topic of boiling heat transfer in miniscale geometries focuses the ever increased interest of researchers in recent years. However, most of the works are related to mini- and microchannels and much less to minigaps. Meanwhile, the minigaps allow for more comprehensive experimental studies, i.e. flow visualizations due to flat, two-dimensional configuration of flow. The results of experimental investigations of a model plate heat exchanger, composed of a single plate with a heat exchange surface of 0.1 m x 0.2 m, made of brass are presented. The working fluid is pure ethanol. Between the plate and the cover of the exchanger, a 0.5 mm and 1.0 mm thick minigaps are arranged. Minigap 0.5 mm has been compared with an equivalent minichannel structure (a set of 50 parallel minichannels) with an equal cross-sectional area (rectangular 1 mm x 1 mm). The section cover was transparent in order to make simultaneous registration of flow structures along with the measurements. The heat is supplied using a water circuit, where the temperature and flow of the water can be regulated in the constant temperature water tank. The flow configuration of the exchanger is countercurrent, with the vertical flow of ethanol from the bottom to top. The inlet and outlet manifolds are arranged as trapezoidal (Z-type design). Authors have analysed the efficiency of heat transport and pressure drop depending on the system operation parameters. Attention was paid to the issue of even distribution of the working medium (flow maldistribution). The visualizations have been thoroughly analysed in order to better understanding of the process. The main advantages of the presented work are: a) direct comparison of minigap and minichannel structures while standardizing all other parameters, b) simultaneous visualization made with the use of fast shutter speed camera for better understanding of the process.