I know the charts don't support this and I did it more as a test than anything... I have a 100,000 BTU hayward running on 50' of 1/2" od line. teed off of a 1/2" black pipe line feeding my grill. I have clocked the heater at the full !00,000 BTU several times. Not sure of my line pressure but, I have never asked for an upgrade.