Cooling Fans

[astronut (John)]

My 12" Lightbridge has the factory fitted muffin fan mounted on the rear cell.
In the 5 years of operation it has worked well.
I leave it on all night without any concerns about vibration.
There are some occasions that the primary mirror will still show some slight fogging around the edges and what appears to be a very fine layer of moisture on the rest of the mirror.
I've read up on mirror cooling and found that larger fans won't necessarily make any difference.
Would a faster spinning fan, the same size as the original make a difference?
I'm open to suggestions.....HELP.....

[icytailmark (Mark)]

do you use a light shroud? Maybe you could buy dew heaters?

[mswhin63 (Malcolm)]

From my understanding of the fan is placed in the centre to extract the air but there is still a natural flow of air around the open areas of the rear cell.

I have a similar issue with my Sky–Watcher, so I intend to create a seal around the other exposed areas. This will allow the extraction fan to increase its airflow through the fan itself. I expect that I will create a solid aluminium plate and then place the extraction fan on to the plate. I believe most Astrographs work in this way.

It would be nice to know if anyone also experiences this problem and whether or not a full plate will actually work.