Exterior combo door freezing shut
Hey GBA im having issues with my exterior combo door freezing shut at the seals,
Im located in canada climate zone 7, as it drops below 0 celcius my outer door freezes around the seals
My home is new construction, extremely air tight , ICF walls , close cell spray foam attic. Hrv controls the humidiy in the house and we adjust it to keep condensation from forming at the bottom of the windows
My original thought was that an improperly balanced hrv was causing a positive pressure inside the house, pushing warm air out the door seals. I had the hrv balanced to neutral and still had the same issue, now i have tried adjusting the hrv to be slightly negative pressure and im still having the freezing issue
this if a few other things ive tried
– leaving the window on the outer door open
-putting plastic window film on the inside window of the exterior door ( this helped with the freezing but didn’t solve it )
Any thoughts or ideas?
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Replies
Your "interior" door--the insulated, exterior door--is keeping heat from the house from reaching your storm door. But air and moisture will still leak past the door seals and the moisture is condensing on the storm door. The simplest solution would be to remove the gaskets from the exterior door; it will still cut down on wind and protect the insulated door. Or invest in a higher-quality, European-style insulated door and get rid of the storm door.
I'd check those seals -- both sets -- to see if they have any leaky spots. I think moisture is leaking in there, condensing out around the seal, then freezing.
I've not had this happen with a door to a house before, but I have had it happen with doors to greenhouses (which tend to be very, very humid by design). What I did with the greenhouse was to design a special type of heat tape that was integrated into the door frame and then powered by 24V AC. Around 150 watts or so was used to keep the door frame slightly warm, which eliminated the freezing issue. This is not a particularly green way to go, since it's a constant use of energy, but it was the only thing that worked after we had already tried various seals and insulating panels.
You may be able to put a heat tape into that interstitial area between the doors. You don't need it to be "warm", you only need it to be a tiny bit above freezing to avoid issues if you try this.
Edit: I really like Michael's idea to remove the seals on the outermost door. That's very simple, elegant, and cheap too! Doing that would allow the humidity level in the interstitial space to be roughtly equal to outdoors, which is going to be very dry in the winter. No moisture means no icing. In the greenhouse example I mentioned above, the VERY humidy greenhouse air would leak out around the door, which is a much more severe situation than what you're dealing with.
Bill
Thankyou bill and michael , ill try it and report back!
Even with the HRV set to slightly depressurize the house, it could easily be overpowered by wind pressure effects that pull air out the door depending on which direction the wind is blowing. I suggest testing the seals of both doors for leaks. Test each door individually with the other open and all bath and kitchen exhaust fans running.
thankyou guys for your input, i agee it would not take much wind to push/pull air out the door.
happy to report back removing the weather stripping on the exterior door has solved the issue, these types of doors should not be sold in my climate,