How can a price ceiling make consumers better off?  Under what conditions might it make them worse off?

If the supply curve is completely inelastic a price ceiling will raise consumer surplus.  If the demand curve is inelastic, price controls might result in a net loss of consumer surplus as consumers willing to pay a higher price are not able to purchase the price-controlled good or service.  The loss of consumer surplus is greater as compared to the transfer of manufacturer surplus to consumers. If demand is elastic (and supply is relatively inelastic) consumers in the aggregate will enjoy a raise in consumer surplus.