A cold room vent comprising: a housing mountable to a cold room structure, said housing having a first pressure exhaust port and a second pressure exhaust port ; a gravity biased first pressure exhaust valve mounted to said first pressure exhaust port having a first weight which allows the opening of said gravity biased first pressure exhaust valve at a first air pressure level, the first pressure exhaust valve comprising a first mounting stem extending through a valve mounting hole of the first pressure exhaust port , the first pressure exhaust valve further comprising a head, the first weight comprising one or more weights coupled to the end of the first mounting stem , wherein the one or more weights gravitationally bias said first pressure valve towards a closed position; and characterized by a gravity biased second pressure exhaust valve mounted to said second pressure exhaust port having a second weight which allows the opening of said gravity biased second pressure exhaust valve at a second air pressure level greater than said first air pressure level, the second pressure exhaust valve comprising a second mounting stem extending through a valve mounting hole of the second pressure exhaust port , the second pressure exhaust valve further comprising a head, the second weight comprising one or more weights coupled to the end of the second mounting stem , wherein the one or more weights gravitationally bias said second pressure exhaust valve towards a closed position, whereby the gravity biased first pressure exhaust valve opens the first pressure exhaust port at the first air pressure level and the gravity biased second pressure exhaust valve opens the second pressure exhaust port at the second air pressure level. a housing mountable to a cold room structure, said housing having a first pressure exhaust port and a second pressure exhaust port ; a gravity biased first pressure exhaust valve mounted to said first pressure exhaust port having a first weight which allows the opening of said gravity biased first pressure exhaust valve at a first air pressure level, the first pressure exhaust valve comprising a first mounting stem extending through a valve mounting hole of the first pressure exhaust port , the first pressure exhaust valve further comprising a head, the first weight comprising one or more weights coupled to the end of the first mounting stem , wherein the one or more weights gravitationally bias said first pressure valve towards a closed position; and characterized by a gravity biased second pressure exhaust valve mounted to said second pressure exhaust port having a second weight which allows the opening of said gravity biased second pressure exhaust valve at a second air pressure level greater than said first air pressure level, the second pressure exhaust valve comprising a second mounting stem extending through a valve mounting hole of the second pressure exhaust port , the second pressure exhaust valve further comprising a head, the second weight comprising one or more weights coupled to the end of the second mounting stem , wherein the one or more weights gravitationally bias said second pressure exhaust valve towards a closed position, whereby the gravity biased first pressure exhaust valve opens the first pressure exhaust port at the first air pressure level and the gravity biased second pressure exhaust valve opens the second pressure exhaust port at the second air pressure level. <EOS>