I recently upgraded my greenhouse by installing a flue for my wood burner, and surprisingly, it was much easier than I expected. If you plan on doing something similar let me give you some reassurance and confidence you CAN do it too. Here’s a quick rundown of how I did it:

The Process

To cut the hole for the flue, I used a sharp Stanley knife and a steel drill bit. First, I drew a circular outline where I wanted the hole, using the metal frame from the flue flash kit. I then marked a cross in the middle, dividing the circle into four quarters, which helped guide my cuts. 

By doing this I was also able to hold the sheet from within the center while cutting the outer circle, ensuring the whole sheet didn’t pop out of the frame.

• I started cutting down along the cross first, as it aligned with the polycarbonate lines inside the sheet, making it the easiest cut first.

•I carefully worked my way around the circle, making small incisions along the edge to get a clean, precise cut.

Challenges and Tips

Since my greenhouse was already set up and the back was against a wall, I couldn’t access both sides of the sheet. To make the job easier, I positioned the flue near a roof window, allowing me to access the sheet from both inside and outside. This was useful for being able to hold the sheet for the first couple of cuts. If you’re installing a flue, this setup is much easier if you can access the area from both sides or if you plan ahead during the initial build.

Why This Upgrade Was Necessary

Before, I was using the wood burner in a roof window, but it created drafts, and smoke would sometimes blow back into the greenhouse. Now, the flue is safely installed, ensuring continuous heat without risking damage to the polycarbonate.

Immediate Results

Within 20 minutes of using the wood burner, the greenhouse temperature increased by 10°C, making it perfect for extending the growing season and creating better conditions for plants.

Takeaways

• Plan Ahead: If building a greenhouse, install the flue before the sheets are in place.
• Use a Guide: Mark your cut with a felt-tip pen to ensure accuracy.
• Position Carefully: Make sure you can access the area from both sides or use a roof window.
• Be Precise: Small incisions along the edge of the circle ensure a cleaner cut.

This upgrade has transformed my greenhouse heating, and I’m thrilled with the results. If you’re considering a similar project, feel free to reach out for tips or advice!