PD619063 - Expansion Valve Kit - TXV - 4 Ton4 Ton Expansion Valve Kit (TXV) The Type CBBI Thermal Expansion Valve is a balanced port valve with integral check valve assembly. The CBBI valve is designed for use on residential and small commercial heat pump systems which require a check valve. Features Balanced port Internal check valve Straight through or angle configurations Mesh insert strainer For residential air conditioning and heat pump installations For light commercial air conditioning