Just installed the Recpro Houghton 9.5 btu to replace the horribly noisy Coleman Mach 13.5. It is SO quiet!!! We have never used the Coleman because of the noise. We ordered it with our TT not knowing it was a waste of money. At least I should be able to get something out of it on Craig's list.
The new unit was $1150. 9.5's are a bit more expensive that the Recpro 13.5 but it is lighter and less power requirements. The unit is about 1/2 the size of the Coleman with a much lower roof profile and 3/4 the weight. With the lower power requirement, I was able to run it off the house 20amp/110 plug as a first run test. It lowered the TT inside temp 15 degrees in under 2 hours and the TT has been heat soaking for weeks. Outside air temp was 91.
Like Granit I installed the roof flange with butyl tape followed up with XTRM sealant around the edges. The inside ceiling mount also did require some Dremel work at the corners to allow for sloppy roof frame welds.
Looking forward to some summer camping, but most of our trips are Fall, Winter, Spring. Now my DW wants me figure out how to quiet down the furnace!