The Poland international was signed on a season long loan spell from Genk on transfer deadline day, he was brought in to take the place of Mark Bunn who moved on to Norwich City.
Jake Kean is also looking to better himself so there is now competition for the place between the sticks.
"I want to make a pressure for every goalkeeper here," said Sandomierski to reporters.
"I respect everyone but I will do my best in training and will look to get my position as soon as possible."