Wyeast 1056, American ale. From the Wyeast website,
"Very clean, crisp flavor characteristics with low fruitiness and mild ester production. A very versatile yeast for styles that desire dominant malt and hop character. This strain makes a wonderful “House” strain. Mild citrus notes develop with cooler 60-66°F (15-19ºC) fermentations. Normally requires filtration for bright beers."