Machine Gun Furnace - Humorus, but doesn't do its job right.

I have a furnace-like object I made. What it does is you put 2 items in and it compressed them together creating a new item. I used the furnace template available in the software, however there are 2 errors.

1. It does not compress unless it is open.

2. It compresses stuff super fast, like 30 items a second, and as a result of this, could result in ear bleeding.

It was funny the first time it was coded, but now its not annoying. I'd like to change it to where it works while not being opened, as well as a way to slow it down.