I just installed my own pool heater and this makes me glad that I followed the directions. Everyone tried to tell me that I "should" be able to run a smaller size. I figured that the larger pipe size had something to do with demand for volume when it did kick on. That is what I think anyhow, how long of a run is it? I would say that even if you go back fifty feet and retie in with 1" it would make a diference, personally I would go all the way back though. I used the yellow plastic pipe like what the gas company uses now, you can buy compression adapters to go to male pipe thread for the ends. You have to go to a heating and air supply house or possibly a plumbing supply house for the material though, but it is not a hard job really. The digging is by far the worst of it.