Oliver is right. To vent is to give free expression to strong emotions, such as anger or frustrations. In your sentence the house heads in normal English would mean heads of house, who would be the leaders of the units of an organisation, such as a boarding school. These leaders had a chance to express their anger/resentment/frustrations freely before things went out of hand. There are the following mistakes in the sentence you quoted: 1. "Vent" is transitive: it must take an object, such as anger. We cannot simply say "They could vent". 2. "Could - went" verb agreement for the conditional.

It seems to be the verb "to vent" = to give free expression to (a strong emotion).

To let it all out!

Vent means cool down, or create some kind of breeze, depending on what are you trying to mean, but what you might be looking for is cool down, hope that helps :)