What type expansion tank is supplied in the hydrobox?
A bladder type of 2.6 gal (10 l) volume is provided in the hydrobox and comes precharged at 14.5 psi (1 bar) with dry nitrogen. Nitrogen has bigger molecules than air and is less likely to penetrate through the internal bladder in the expansion tank. It is highly recommended to use dry nitrogen when recharging or adding additional pressure to the expansion tank. Refer to installation instructions to calculate pre-pressure of expansion tank.
