Gerard the taps are listed as 1/4 BSP both ends. I can't imagine that both taps would have a duff thread at the outlet? Are you sure that the threads in your union nuts are not damaged/stretched? Can you try the tank end of your old taps in the union nut before you set too with a 1/4 BSP die. Ron

email (option): ronpier@talk21.com

I had to run a die down both output threads to clean them up. The off thing was there was no visual issue or damage - but it's all good now.