Blast Freezer Within Freezer

I am planning to install a blast freezer within a walk-in freezer. Someone has told me that there will be door issues since the blast freezer door is to be located inside the freezer.

I was told the inside door will most likely get stuck since the blast freezer temp will be at -40C while the freezer temp will be at -25C, and that door heaters normally can't handle below freezing temperature on both sides.

The blast freezer will also be run on an intermittent basis, so will I have to keep the heater on the door running even when it's shut?

Is there any way I can get around this door dilemma?

rickmor,

why you have to put the blast inside freezer room?what is the product load?here in manila i have yet to see installation like you have in mind.

I don't see any problem with the door heaters.
I even saw heaters on -80°C rooms in a -20°C room. This thread was on RE some years ago.

I have seen this done and done it myself on occasion.
Most of these did not use conventional doors. Just fairly tight fitting wooden ones.
At any rate moisture should not be much of a problem, since you are already at -25C.
We had a small blast with 5 foot wide Butchers Boy door made in the 1940s. We used no heaters. The floor sweep was a problem, so we just put a piece of foam pipe insulation under hte door before we started it. Crude but effective.

The doors could be problematic if the product itself carries moisture with it. But since the temp on the other side is -25, that problem is not very serious.