Are these CAN filters really that good?

During bloom, can you smell ANY pot smell out the discharge side?

I would hate to waste all that hot air during the winter. Could I discharge the exit air to the rest of the house or atleast run it to the crawl space under the house rather than just blowing hot air into my backyard when its 20 degrees out side . It would really have to be clean air, I dont want to smell it in the living room.

Thanks

Yes they are that good. If all of the connections are sealed with duct tape properly you will not smell anything but fresh air coming through the filter. They last about a year before the carbon needs to be replaced, your nose will tell you when to change the carbon.
Yes you do not have to vent the exhast outside of the house. I would recommend that you not exhast back into your grow area.

Yeah they work good. Just let it recycle the air in the flower room. You'll probably have to leave it on 24/7 till done flowering. The stinkiest part is usually the hanging and drying.