Apologize but I did not read the getting started suggestions before posting to a thread that was over a year old.
I have not been able to find information for my situation. I am upgrading from a 250 BTU Jandy lite 2 that has worn out. I had it professionally installed 12 years ago (permits etc) but was not attentive enough as to the requirements. I am running a two stage system now. It is a 2 psi Delivery from the gas meter with Mult. 1.07 in a 1" flex running for 150' down hill to the heater. I want to go up in BTUs to 400 if possible. Not that I need it to heat, but just to do it quicker. Gas company says it shouldn't be a issue. But for some reason I didn't hang up the phone after talking with them very confident. I do not want to kill a new heater by not having the volume I would need. From reading some discussions here in earlier posts, it sounds like some of you have some experience with what I am going through.
Can anyone reference a web page that I could look at which has the two stage calculations and distances? Or answer as to if I am capable with set up I have now in place to step up to above 250 BTUS without harming a new heater ?
Also I am looking at Jandy/ Hayward/ and Lochinvar so far if anyone has recommendation.