Farbulous Creations did a great video on exhausting through the roof, but there is a lot of great info even if you are not going through the roof. You can find the video at the end of this article.
There are some important considerations when exhausting your Thunder laser:
Do not connect the exhaust output of this laser to any existing exhaust systems. Please consult a qualified HVAC or industrial mechanical professional.
Even if you have great exhaust flow out, you must have the same volume of air coming in. A vacuum is not what you are looking for. This can be realized easily if you are in a somewhat airtight area like an interior room in your home or business. The negative ambient pressure is created by the laser sucking 400 CFM out of the room. If the incoming air into the room and the laser is not sufficient, the fumes will not escape.
You want negative pressure throughout the exhaust system itself. If you are forcing the exhaust through the duct system and it can be ejected through holes in the ducting, gaps in fan housings, loose connections, etc... this blows it forcibly back into the room.
The best solution is to mount the fan right at the exit (or as close as humanly possible) so it pulls the exhaust though the ducting. Some mount their fans outside and have a true negative pressure system. We should clarify that mounting the blower on the exterior is only for fans that are sheltered and/or rated for outdoor use.
Here is one setup where the fans and exhaust systems are easily accessible for inspection and maintenance. The fan outlet is less than 24" from daylight. The left one is a Cloudline S6 and the one on the right is a 4" S series. The components in this article were used in this installation:
And, restrictions of any kind can cause major issues. 6" diameter minimum on all ductwork. Use the shortest runs possible. The helix reinforced cloth flex ducting is plasticized but it can still be permeable if under pressure. Rigid ducting is recommended for long and/or complex runs.
The exhaust ports on most Thunder Lasers are Ø5.7" (145mm). The exhaust blower fan, 2 6M (19.5') sections of flexible cloth-reinforced ducting, and 3 hose clamps are included with every machine. The nearest standard venting size in the US is Ø6" (152.4mm). We recommend a 6" weighted damper exhaust vent hood for exhausting through a wall. Like the one below:
It is important to get a vent hood with a damper to keep the outside air from entering the laser, especially in the winter. Cold air from the exhaust system can affect the tube temperature.
If conditions are below freezing this could be an issue. In colder climates, it may be beneficial to leave the lid up on your machine to help equalize the ambient temperature inside the machine.
A spring-loaded damper may be more efficient at remaining completely sealed but if and when the spring fails, the damper is rendered largely ineffective.
A weighted damper is less prone to failure. The exhaust system must also be periodically inspected, cleaned, and maintained for optimum performance and safety.
You may also want to add one of these for good measure if its super cold:
You will need one additional 6" hose clamp (I think) and some duct tape to terminate the connection of the ducting to the vent hood. The difference in diameter makes the exhaust duct a very tight fit but it will adequately engage the rigid ducting.
Also, watch out for the wire in the ducting as it is very sharp. Trust me on this :).
More information on preventative maintenance can be found here: Preventative Maintenance Checklist
The Mini 60 and the Nova 24 come with an axial inline fan and is pretty quiet.
Specs on the Nova 24 and Mini 60 stock fan: W150 Inline Exhaust Fan Specs
The Nova 35, 51, & 63 come with a cap start centrifugal fan which moves a lot of air but is a bit noisy.
Specs on the Nova 35, 51, and 63 stock fan: CZ-TD550 Exhaust Fan Specs
Farbulous Creations did a great video on exhausting through the roof, but there is a lot of great info even if you are not going through the roof. Awesome job Ron!