Roll Up Rapid Door gets sucked on defrost end

[georgedvf]

Hello my friends.
I'm having this odd problem, we installed a big freezer (3,600m3) at -20°C whit one rapid roll up door (2.50mx4.80m) that is getting "sucked" into the room when electric defrost ends. I have installed two pressure relief valves with a capacity of 7,300lts/min (calculated on formula Q=k*dT*vol).

I have no clue on what is creating this effect, please advice.

[Magoo]

Possible that the coil chill time period before fans restart is too long and creating a rapid air density change when fans do start. Alternatively if you have multiple evaporators, stagger the defrosts, not all at once
I had the problem of blowing rapid doors out, never really had them sucking in.

[georgedvf]

I'll try setting up less chill time to see how it works.

[benijoseph]

Hello my friends.
I'm having this odd problem, we installed a big freezer (3,600m3) at -20°C whit one rapid roll up door (2.50mx4.80m) that is getting "sucked" into the room when electric defrost ends. I have installed two pressure relief valves with a capacity of 7,300lts/min (calculated on formula Q=k*dT*vol).

I have no clue on what is creating this effect, please advice.

dear friend,

u got excellent sealing of doors , this problem is because pressure inside unit reduced due to low temp, I faced similar problem we solved it by putting one way valve into the cabinet,

regds.

[khaled hilaly]

please reduce maximum defrost time and maximum temp for defrost ending

[lhill]

you need to install more "equalizing valves" or make shure the ones you have are working

[smpsmp45]

We also faced similar problems. We placed pressure equalizer valve just above this roll up door & till date this issue has never been noticed again.

[georgedvf]

We already had two equalizer valves working above the door and still had the problem.

What we did was programing auto open events on the PLC, so those auto-opens works for releasing pressure.

Thank you all.

[Magoo]

Still cannot understand why the room pressure drops and sucks in the flexible doors. OK I have had rooms over pressurizing and blowing doors out and sliders being blow off runners.
Possibly the condensate draining is so high and pipe is too small and velocity is high and dragging air from room/enclosure even with a P trap in drain. A bit like taking plug out of a bath full of water. Velocity sucks air.

magoo