What is the reason for the slow warming of the water bath sterilizer cabinet? Troublesome people to point out one or two!

I am also operating a water bath sterilization cabinet, I do not know and I operate the same phase is not the same, the principle should be more or less the same, like you say this case, I am operating this way, the reason is that the cabinet pressure is too high, the steam can not go in, manually exhaust 1-2 seconds, the steam immediately go in, we began to start like you do not know why the steam can not go in, the warming is very slow to find the reason, and then it is to use this method! We started like you why the steam can not go in, the heating is very slow, can not find the reason, and then this is the solution.