Keith
As much as I prefer to vent a central vacuum outdoors, however in my humble opinion I feel like it is better to have a central vac equipped with a ActiVac III HEPA exhaust muffler. Not only you won't pollute the air outdoors but also you won't have neighbors to hear the noise of your central vac while running and you won't have bugs or insects to crawl the inside of your exhaust piping. There was a moment or two when I wondered why there were dead wasps or yellow jackets inside the motor compartment of our Eureka central vac which is vented outdoors, didn't took long to figure out that there was a wasp nest built right up where the end of exhaust is coming out at. And that's definitely a fire hazard if you blocked or clogged the exhaust piping of your central vac.
Also regarding central vacs with thru-flow motors in it. I would highly recommend to use only genuine bags, not generic. And/or I would highly recommend to use cloth bags, not paper. Otherwise without multiple layers of filtration, you would most likely to have bearing noises. That's one of the reasons why I'm leaning towards on getting the MD Modern Day M715h for myself that uses a bypass motor over the MD Flo-Master F650t that uses a thru-flow motor.
[URL unfurl="true"]https://builtinvacuum.com/product/activac-iii-exhaust-hepa-filter/[/URL]
