I have a 36x18 inground pool with a 21 yr old heater that worked great for most of that time. I'm replacing the Laars Lite 325K nat gas pool heater with a Raypak 266k or 336k nat gas heater. The Laars 325k and Raypak 366k are basically the same size with plumbing and most connections the same. Is that a safe assume the Raypak 336k heater would use the existing Laars gas line without issue or should I down size to Raypak 250K?