Generator Shed Sound Test #3 - (Full sound insulation, side baffles, and muffler)

This is the third sound test of my Suncast shed, which I am turning into a generator shed/quiet box. This time, I have added the Rockwool insulation to the walls, Kilmat sound deadening vinyl to the lid, side baffles to the air inlet/outlet, and my FrankenMuffler to the exhaust. The FrankenMuffler is a 20 gallon galvanized trash can that has a perforated pipe running down the middle and an outlet on the bottom. The rest of the can is filled with mineral wool insulation, which is excellent at sound absorption and is fireproof to over 2000 degrees F. The exhaust shouldn’t get above a couple hundred degrees. As you can see in the video, this muffler did an Excellent job of deadening the sound! While the rest of the ideas for the shed were dug up from other videos and forums, I haven’t seen anyone take this approach to quieting a generator exhaust.
Links to the 3 sound tests, and the final project results (below)
Generator Shed Sound Test #1 - (No Sound Insulation):
• Generator Shed Sound T...
Generator Shed Sound Test #2 - (Sound Insulation Installed, Side Baffles, but no muffler):
• Generator Shed Sound T...
Generator Shed Sound Test #3 - (Full sound insulation, side baffles, and muffler):
• Generator Shed Sound T...
Final Project video:
• DIY Generator Shed Bui...

[@jerryhall4678]

Curious where you live and what kind of temperatures you've experienced? I have the Generac 17500 it's a beast with a fairly large lifetime 6 ft 3.7 in. x 3 ft 7.5 in. x 5 ft 9.4 in (75.7″ x 43.5″ x 69.4″ ). I used several bags of the Rockwool for sound proofing and it works great. I did a propane conversion kit along with about 200 gallon of non ethanol storage and 230 gallons of propane. My goal is 15 days minimum without power. With hard start kits on my 5 ton and 3.5 ton the generac will handle that easy along with 3 refrigerators and 3 freezers. Initially I was concerned about sound but now that my neighbors have installed 24KW's I realize in an emergency the sound won't matter as much as the AC :-). My problem is the internal temperatures. Initially I had 2 6x6 intake vents and a 10x10 coupled with 2 Hessaire gable fans from HD. I had 1100 CFM and 300 CFM. When I reached 130 degrees the 1100 CFM shut down. Since that time I replaced the 10x10 with a 22x22 and added another 900 CFM for a total of 2400 CFM. Yesterday I ran it for an hour and still reached 118 degrees and that was on a cool day in Houston only 85 degrees. With the rockwool I can reach 120 degrees in July and August on the inside of the shed without having it running. If not for the 160 feet gas line run I would should have just invested in a 24KW trust me my cost is comparable at this point. I really like the detail you've put into this genset and would welcome your opinion. I'm very concerned that if I over heat the fans this thing could melt burn down if it was running overnight. Would like to chat offline to pick your brain. I'm using about 30 inches of walker 1 1/2 inch flex exhaust pipe similar to you however it exits into a dry vent that's mounted to the shed. I wrapped the pipe with header/exhaust heat tape and I'm considering wrapping that in a 4 inch dryer pipe stuffed with rockwool or perhaps going with a longer exhaust pipe like you've done to get that heat away from the structure.. I realize exhaust can run 600 degrees but I have to find a way to keep the temperature down. I apologize for the long winded comment.

[@ernestkanu1247]

These measures worked for me:
1. Adding a thermoflex reflective shield (smart shield is the brand I bought) over the rockwool. It adds an additional layer of heat reduction and sound deadening.
2. I found that adding a horsemat on the floor (Harbor Freight sells them at a bargain) not only reduced the decibel coming out of the shed but surprisingly and unexpectedly reduced the temp inside the shed by 4 deg F. I did not expect it to lower the temp, my intention was to lower the noise!
3.Mounting the inlet vents as low as you can, mine is 5 inches from the base, allows the cooler air on the ground.
4.Mounting the exhaust fan higher and opposite the inlet vents for cross ventilation allows for the hotter air which naturally rises up, to be moved out easier.
5.Finally, I wrapped the exhaust flex pipe with 1inch of ceramic fiber blanket before wrapping it up with heat tape .After wrapping with heat tape, I then sprayed the heat tape layer with "HI-TEMP silicone coating”.
I recently completed building my generator wood shed (54ins L x 52ins W x 48ins H). Without the gen running, I measured the inside shed average daytime temperature at 74F and Nighttime in the lower 60s, with outside daytime ambient temperatures of 80 to 90F in the Pacific Northwest. I have been lazy to move the generator ( Westinghouse 12000DF ) from the garage where it stays when not in use to the shed, to measure what the temperature is when the gen is running. I Should try that soon obviously. So far I am impressed with the result without a running gen in the shed. Good luck!