Thank you for your question on the model RVK1A roof cap kit. The four inch metal duct connector from the RVK1A is not available as a parts item. To use the 636AL roof cap, the duct work does not actually get connected to the roof cap. The duct work goes up through the roof and the 636 fits over the top of it. For further assistance, please contact our Technical Service Department at 800-637-1453.
Date published: 2013-10-23