My mother recently had a combi boiler installed after having a traditional hot and cold water system previously. What concerns her is the steam which escapes from the vent outside. When the engineer left she noticed that the temperature was set at 90 degrees! She had someone alter this and now I'm wondering if the pressure is set wrongly?
I suspect what you call the vent is in fact the flue, on a condensing boiler it is quite normal for a lot of steam to come from this, there is nothing to worry about.