Dempsey netted an injury-time equaliser last night.
He said: "It is always good to get four points against United in a season. It's nice to get the point tonight when we were looking at a defeat, but their goalkeeper [David De Gea] made some great saves in the first half.
"We take a lot of confidence from this point because we had a lot of possession, a good number of chances that we created and shots on goal. It keeps us on a good run of form with three tough games coming up. We have three away fixtures and it's about getting the right results in those matches."