Had three 50-gal American Standard water heaters installed Dec. 2009 Two upstairs in attic, one downstairs at ground level. Attic location used because heaters being replaced were up there. Upstairs units are both Mod. GR-50T2-3-6-Nat. Have had continuous problems of pilot lights on upstairs units going o out. Plumbing co. that installed them has had to come out and re- light since I am physically unable to climb into attic, then lay down to see if pilot is lit. Installer said in summer (when all pilot-light trouble was en= countered each year) hot, stagnant air gave signal to unit to shut off pilot light due to insufficient air. Said I would have to provide more ventilitation to keep air moving more in attic during summer. Suggested some kind of electric roof vent fans. This was not mentioned at time of sale/installation; installing company re- fuses to take further responsibilty for solving problem. Attic has extra-high ridge with space enough for a second story, so volume of enclosed air in attic is much larger than normal.