Improve Venting for OTR Microwave

[SteveLeM]

Looking for opinions/advice on what i want to do to improve the ventilation through my OTR microwave.  Basic plan is this:

• Add 600CFM remote blower in attic with vent piping to microwave and out roof.
• Remove blower inside microwave to open airflow
• Extend microwave blower control wire to remote blower
• Add stainless "visor" extension on front of microwave to extend capture surface.
• 79% of original size (was 640x427) - Click to enlarge

Thinking is i can now suck more air, but still control vent from switch on microwave and allow microwave to automatically turn on vent if it signals for cooling.

Thoughts?

[SmokeyKitchen]

Resurrecting this as I've thought about this heavily. I have a small kitchen requiring an OTR microwave. Mine is a GE.
Here's a major factor that needs consideration:

The microwave body is under positive pressure. Even if you have good venting, the body is not sealed up which allows dirty air to escape every crack and crevice. If you had white cabinets, you'd easily see a film where this is air is escaping out the top of the device.

I've made an arduino shield for my furnace that piggy-backs onto my furnace that allows the 24V AC signals to be monitored and controller a booster fan. With a few changes to some resistors, it can be updated to handle different voltages. It goes through an opto-isolator. I've attached a pic of the fan motor wiring diagram and it says it's 120V.  It's not a big change to make that work.
Four wires come back to this board from a fantech blower:  10V pwr, Grnd, PWM speed command, Tach.
A transistor is toggled to control the speed. An interrupt reads the tach. This can all be adapted for this use case.

What I don't know is what goes out to the fan and if the fan line will stay on if there's no motor connected.  If it does work this allows for full control of the fan via the buttons on the panel. If there's some sort of open circuit protection, there might be an issue.



This is not a huge undertaking if anyone still has interest. I'd love to be able to buy an old fan on ebay, lop off the harness, into this module. 4 wires go out to an inline fan and we are done.

With some creative component selection, this could potentially be powered by the micro entirely with no additional power needed. I don't know that much about analog electronics so I'd be out of my element there but if we did it with a microcontroller, it would definitely work with a slight startup delay.

 

[SmokeyKitchen]

Forgot to add the note about the positive / negative pressure.

By removing the fan from the micro body, you're putting the whole micro under negative pressure via the downstream fan which will keep your kitchen cleaner and keep the exhaust air from escaping.