On Miller MG2R furnaces some contractors are finding the following.

During a service call, water leakage was observed between the secondary heat exchanger exit plate and the heat exchanger face plate. The face plate has a large cut-out and is sandwiched between the secondary plate and outlet header box when the header box is secured with fasteners. The outlet header box gasket overlaps the edge of the faceplate, allowing contact with the secondary heat exchanger plate. The gasket design has since been revised by the manufacturer to prevent this issue. If desired, the servicing contractor can apply a bead of high temperature silicone sealant between the secondary plate and face plate when replacing the outlet header box. But hopefully the issue has been taken care of on future units. We do not currently have a date ranges when these were affected.

MG2R-045

MG2R-060

MG2R-072