Catalyzes the NAD(+)-dependent oxidation of formaldehyde and acetaldehyde. formaldehyde + H2O + NAD(+) = formate + 2 H(+) + NADH acetaldehyde + H2O + NAD(+) = acetate + 2 H(+) + NADH Binds 2 Zn(2+) ions per subunit. Homotetramer. Belongs to the zinc-containing alcohol dehydrogenase family.