Hey Ryan,

We are located in Minnesota and primarily install our radon systems with fans in the house or garage attic. All piping in unconditioned spaces is wrapped in R6 insulated flexible ducting. I don't believe these systems are very susceptible to freeze-up, as we have never received a call about one being frozen.

We have been including an option for heat cable for the last few years for our customers where an external system is the only feasible solution. The homeowners with the heating cable don't seem to have freeze-up issues.

Here are a few videos we have about frozen radon systems.
Heat cable experiment- https://youtu.be/BunkB3zGgUw
Permanent heat cable install- https://youtu.be/ooWqGVEQEtY
Signs your system has frozen- https://youtu.be/huaZcBEjAxc

We have since changed to having the heating cable hard-wired with a switch rather than having a cord to plug in.

I believe fan manufacturers say to leave the fan running in the event of a freeze-up, but you may want to check with them.

I have heard that some mitigators disconnect the discharge piping above the fan during freeze-up conditions.

We also have noticed that critter guards tend to cause icing issues, so we only install them if there are trees that may drop debris down the discharge or if the homeowner has squirrel issues.

Using 4-inch PVC piping on external systems and on the discharge of internal systems also seems to help, as the system would take longer the freeze compared to a 3-inch system.

I hope this help!
Jesse

Thanks for the post, Colin! I'd love to chat with you about how you calculate the design pressure. That's something I've always wondered. I'd also be interested in your spreadsheet.

Thank you!
612-474-1004 ext. 3

Here's a link to the Professional Contractors Guide https://carst.ca/resources/Documents/Reducing%20Radon%20Levels%20in%20Existing%20Homes%20A%20Canadian%20Guide%20for%20Professional%20Contractors-E.pdf

We have received a handful of freeze-up calls in the last week. The lows here in Minnesota have been in the teens below zero and the highs around zero for the last week or so.

I have never really like the idea of telling customers to wait until it warms up, so we decided to try a few experiments to fix the freeze-up issue.

We installed roof deicing cable on two houses with frozen external systems—one on Thursday and another last night.

The first one can be seen in this video we posted to YouTube. https://youtu.be/BunkB3zGgUw

The second install wasn't so easy as we had to take the pipe off the house, run five gallons of hot water through it, and then fish the heating cable through with a sewer camera.

I am happy to report both systems have returned to their initial static pressure.

I am hoping this system can be improved upon and hardwired.

Do you have any thoughts on this?

Have you found a better way to prevent system freeze-ups?