I replaced a old room fan last year because it was noisy and sounded like it was going to stop. This year I fired it up after a huge cleaning and the new fan sounds great. After 30 to 40 minites the Fan starts to cut out some. Like its dropping voltage or something. I tried several different times with same results. I did change some piping over the summer to get it away from the house some but nothing major. I switched back to the old fan to see if the new fan had issues. Same results after the stove came up to temp. Any ideas or Thoughts?