What would be a good heater.?

We have a detached garage out behind the house which we converted to a rec room. we have an air conditioner for the summer months, but we've been struggling with heaters for this winter.

the first electric one didn't do the job, so we bought a bigger electric heater one of the guys recommended to us. after about 45 minutes, we could barely feel the difference unless we stood right beside it. So, we turned that one in, also.

try number 3. we got a kerosene heater. it works well, BUT it is so LOUD that one cannot enjoy music, TV, or anything else out there. And when we turn it off, the heat doesn't last.

I only asked in this section because I didn't see a legitimate category for this question from my given options and I thought I met get more replies here.

Anyone have any other suggestions?