I have 12 miners running on my bottom floor - almost a basement - but not. It is still in renovation stage. So, I have a place where two large windows are going to eventually go. I have 2 gable fans mounted on the wall where the windows will go to blow air outside with automatic gable shutters over them. In front of this, I built a cabinet with a division wall between the front of the miners and the exhaust side. The exhaust side encloses the 2 gable fans that blow outside. The front side is enclosed using 4 1"x16"x20" MERV3 air conditioning filters to filter the incoming air from the room. Then on the top of the enclosure - also pulling air out of the exhaust side I put 2 more gable fans that blow the air up. I then built a duct over top of these two fans that bring the air through a 2'x2' hole in the floor going into the main floor of the house (second floor). Next to this 2'x2' hole is another 2'x2' hole - all with side walls and chicken wire put over them so stuff cannot fall into them - including pets. This second 2'x2' area allows air from the main floor to flow into the bottom floor - creating a way for air cycling without having to use the HVAC system fans to try to move the air around. Besides that - the HVAC cannot match the air flow capacity of the gable fans. I have all 4 gable fans on smart outlets. I use an Ecobee 3 thermostat in the house. It can be used with IFTTT to turn on/off the two pairs of fans based on the house internal temp. However, I ran into issues where IFTTT alone was not switching all 4 fans at the same time - sometimes with a few minutes delay - not cool. So, I found the servie APILIO.com that allows deeper logic programming integration with IFTTT. So now, when the temp in the house goes below 69F in the house - IFTTT sets a boolean variable on APILIO to true. This triggers APILIO to turn off the 2 outside fans and turns on the 2 inside fans - this happens practically simultaneously - MUCH better then IFTTT doing it. And equally, if the inside temp goes above 69F, then the APILIO variable of set to false and then APILIO then turn off the 2 fans blowing inside and turns on the fans blowing outside.
With my 8 - S9's and 4 -L3+/++ units - in central - higher elevation WV (USA) I can heat our 1800sqft house down to about 12F outside temps. The 3000+cuft per minute of air flow from 2 gable fans cycles the air fast enough that it heats the house faster than out central HVAC system does. With the cabinet built as is and the ducting (about 8') horizontally away from being directly over the miners - the miner sound is really very mild.
I keep the Ecobee set to heat the house if the inside temp goes below 68 and to cool it to 70. So the house usually sits very nicely at 69 without the HVAC system comming on at all in winter and only to cool in warmer weather. As the miners are blowing outside in that case it works very well. The bottom floor usually stays in the 60's on its own - which actually help to cool the miners in summer. I allow outside air to come into the bottom floor as well so that it doesn't pull cooled air from the house when the HVAC is trying to cool.
The biggest issue I have had so far is Ecobee has been having problems for a while now where they are not pushing the house temp changes to IFTTT consistently - so, on occasion the house ends up at 75+ degrees with the HVAC trying to cool it back to 70 or the heat kick on on the HVAC because the miners are still having their warm air blown outside. I use Amazon Alexa and have setup routines there so that I can tell Alexa to send the miner heat inside or outside - but I cannot do it based on thermostat readings from there - at least that I have figured out yet. But still it is working much more than not - it has it's phases. Sometime this is working very well, other times there are days in a row where it is constantly messing up and has to be manually dealt with. Again - I currently believe Ecobee is 99.9% of the problem.
I am 95% done with a custom circuit design to take this logic over completely - including all temp sensors, fan relays, etc. All designed and coded - but need to get the PCBs made and then I can build it. Then the Ecobee problem goes away.
The 2'x2' holes in the floor are also temporary as this is in the location where a set of stairs will be built from the main floor to the bottom floor - probably this summer.
This has almost completely heated our home for last winter and this. Only a few times - while it is working properly - has the HVAC needed to kick in for lower temps that the miners could not handle on their own. We filled our propane tank before last winter and the gauge has barley moved since. We have a heat pump on the HVAC - but the miners have rendered it useless for heating as the heat well below its cutover point from heat pump to switching over to the propane aux heat. It does still handle the cooling though.
Once the reno is done - I will still blow the fans out of the installed windows and will be adding a duct from outside that can be blended with inside air so that when the weather get too cold for the miners to run - the air can be blended on the intake to warm it a bit. They don't like running near the freezing point. In my top duct into the main floor - I have a small opening there that allows some of the heat to go down there to help heat the bottom floor a bit. As it is still open to outside air - in the low 20's the air in the bottom floor will approach freezing - with this little opening - it keeps it in the low to mid 40's.
I'm really overall pretty happy with it - and will love it when my circuit is in my hands
These images are before I added in the top fans and duct to upstairs.