Examined Booster Heater unit. found manifold gas pressure at 6in wc. adjusted gas valve to 8in wc. couldn't adjust pressure any higher. gas company will need to make adjustment if sooting persists. prv opening. water pressure high. removed and replaced prv and regulator. customer stated roll out tripped many times. will order new roll out switch and return. 5/8/18 Removed and replaced roll out hi limit on heat exchanger. unit heated. good to go.