2020 google nest thermistat and no C wire for floor boiler heat

I think I have read all and still an issue. I purchased a 2020 google nest wifi thermistat for my floor boiler in the basement (it only has R, W, Y, C, G and OB). The existing only has two connections a W and R as just for heat. The new requires a C. I tried a 24 volt transformer hooked up to the R and C wire, disconnected the current R wire, and W. This configuration worked to run the thermistat but did not operate the boiler when above room temp. I did try one leg of the transformer to C and keep the R and W. This showed no power on the nest. I did see someone have the red and transformer wire both in R. I am concerned this may not be best for the Navien boiler. Any advise would be appreciated.
Best regards,
GE