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View Full Version : Freezer Pressure Relief Ports



slctech
07-21-2009, 03:42 PM
Working on a large walk-in freezer. It has two pressure relief ports about 25ft up on either end of the freezer back wall. Both ports are wide open to the outdoors without any flappers, screen, or heaters. Customer says that due to the fact frost accumulates quite excessively around these openings, they stuffed them shut with insulation. Now obviously every time the two large evap units kick on after defrost, the shell about bursts and doors go flying open.
Now I got up there to look at these ports (removed insulation) and they are factory portals, however, I do not see that at anytime flappers or even heaters have been installed. No power has been run to that area to even operate a heater.

The original manufacturer Lowry Refer Box is no longer in business. Freezer is 75ft wide by 75ft deep and 35ft tall. There are two unit coolers pushing a total of 31,000 CFM @ 1066 FPM.

Do any of you guys know of a company that sells replacement parts, dampers, or heaters for commercial pressure ports?
How do you usually like to see these operate/installed in low temperature freezer applications?

I'll be the first to tell you that I am not familiar with the concept and theory behind the proper operation of these. I seriously haven't paid much attention to them over the years, and never had a reason to give them much thought.

Dowadudda
07-21-2009, 07:20 PM
barometric reliefs.

Refrigeration Hardware Supply. Everyone forgets to wire them. Someone took those out if they are not there.

They usually have either a flapper type design, or a plastic ball something or other that acts like a check valve kinda. And the heat is there to keep them from icing up.

kim
07-26-2009, 03:08 AM
See it all the time. Electrician is suposed to wire them up, but don't. Ussually the heater is in there.

crackertech
07-26-2009, 10:53 AM
http://www.totalrefgaskets.com/ they have lots of walkin parts.