Gas pipe size needed for pool heater

The size of the heater and distance of pipe are the big factors. Here is the manual for my Jandy heater.

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I know this is an old post, but I was wondering something...i currently have the JXi260, and I may need to replace it now. Based on the chart, is it possible I could move up to the JXi400? If i'm reading this correctly, it looks like you need less distance for the larger BTU unit? If it was possible to upgrade, I would only consider it if the jump in price is not significant. Again from what I understand, higher BTU unit means heating up the water faster so I figure why not get the higher BTU unit if the cost increase isn't significant.
 
"Less distance" means you cannot run it as far. If your pipe is spec'd out for 260k BTUs the gas plumber would test the output to make sure it will be able to deliver the larger volume that the 400k BTU needs. If it is not able to, they would either replace the line with larger line or could also install a high pressure valve on your gas meter to be able to deliver more gas in the existing line. My 400k BTU heater is run from a high pressure port on the meter.
 
I know this is an old post, but I was wondering something...i currently have the JXi260, and I may need to replace it now. Based on the chart, is it possible I could move up to the JXi400? If i'm reading this correctly, it looks like you need less distance for the larger BTU unit? If it was possible to upgrade, I would only consider it if the jump in price is not significant. Again from what I understand, higher BTU unit means heating up the water faster so I figure why not get the higher BTU unit if the cost increase isn't significant.
The distance in the chart is the maximum length of the pipe allowed to be of that diameter. So it depends on what size pipe was used and how long it is.
 
In Ontario, gas line work must be performed by individuals who are certified and licensed under the Technical Standards and Safety Authority (TSSA). This requirement is outlined in Ontario Regulation 215/01: Fuel Industry Certificates. e-Laws | Ontario.ca

You need to have a certified and licensed individual assess your situation to give you the answer you need.