The VTX-2 is a closed cylindrical expansion tank suitable only for the closed circuit of the solar water heater. Featuring a brass threaded hexagonal ending at the bottom, so that it can be connected to the tank of the solar water heater. At the top there is another brass ending where you can place an 1.5 bar safety valve.
The heated water expands and applies pressure on the air that there is inside the closed chamber. In this way, the space of the tank, where the air is situated, decreases and the water space increases. Once we switch on the tap and decrease the temperature in our solar water heater, the amount of water contracts and as a result the pressure returns to its former state and the water that covered the expansion tank returns into the circuit. In case that we do not use our solar water heater for a long time the water starts expanding until the pressure reaches a decisive point. At this point, the pressure forces the valve to open .Initially the air existing inside the tank is released and then steam is released until the pressure falls back to its normal rates.