Workshop Ventilation

We're in the dog days of Summer, making the workshop unbearable to work in. The original builder of this house decided to run only 30 amp 220 volt service to the workshop. To replace the service, I would have to cut a trench across 20 feet of asphalt driveway. With air conditioning not an option, I decided to try and exchange the air at night when the temperature drops. I purchased a 1000 CFM ventilation fan and mounted it in a window opening to push hot air out of the shop. The workshop size is approx. 6600 cubic feet. At the other side of the workshop, I created two, one way vents to allow air into the shop when the blower runs.

As a bonus, the system will try to warm the workshop during the winter.

To control the fan, I'm using my existing Garden Sprinkler Arduino. I had an extra relay available and merely added a few lines of code to accommodate the fan:

if (topic == "workshop/fan") {

//Serial.println("incoming: " + topic + " - " + payload);

if (payload == "1") {

digitalWrite(ventPin, LOW);

} else { digitalWrite(ventPin, HIGH);



Here's the new setup:

The PVC contraption contains the MCP9808 sensor.

Here's the fan mounted behind my 1930 Boice-Crane bandsaw.

This one way air valve allows makeup air to enter the workshop when the ventilation fan is running. The very thin piece of plexiglass is mounted at an angle of around 10 degrees so gravity keeps it shut. I call it my gravity spring. The "hinge" is some Tyvek tape left over from another project. It remains to be seen how long the tape will last.

The Node Red dashboard:

Red = Outside Temperature, Blue = Inside Temperature, Yellow indicates when the ventilation fan is activated.

If you're interested in importing this flow into your Node Red installation, click HERE to download a ZIP file containing a text document.