Louvers on Evaporators

[Blueboy]

Has any one seen anything like this:-

I have a coldroom-with a pitched roof. The evaporators are located at the bottom of the pitch as it were. They have louvers front and back which close on defrost for some reason! has anyone ever heard of this before!

Because of the louvers fitted to standard evaps we are having problems, airflow related i think, maintaining temperature. I would like to get rid of them. Does any one know any reason why not >?

[desA]

Do you perhaps have a picture?

[US Iceman]

These are probably very old. The louvers are supposed to close during defrost so that the coil can be cleared quickly. Supposedly, the dampers also reduce the amount of heat/water that could leave the coil during defrost.

Seems like a lot of excess contraptions to just defrost a coil.

Was the room ever able to maintain temperature, or was this something that just started?

[smpsmp45]

I had seen such things. It must be very old installation. The basic reason was to maximise defrost effect by closing the louvers at the time of defrost. Infact Thermoking truck refer units has similar systems even now a days. But actually closing / opening louvers becomes more problematic over a period of time.

[sedgy]

the solution could be to disconect the louvers leave them fully open and fit a hold off stat, so when the unit has finished a de-frost the new stat holds off the evap fans untill the evap gets down to 0c or -5c whatever you think apropreate for the job,the stats sensor to be inside the evap casing

[Oregonbythesea]

I have had to change some of these types in the past. I remove the lovers and put a time delay on the fan motors. The louvers will reduce the air flow and cause a cavitation that disturbs the air flow causing some amount of air to short circuit.

[Blueboy]

The problem is that this freezer must stay below -21 . It does usually below the evaporators but not above due to little or no air movement and lights generating heat . There are two rooms back to back with and apex roof. So each room has half of the apex. So a high wall and a low wall with a slanted roof.

The Evaporators are located on the low wall. The room actually just about maintains temperature. Each room has two evaporators capable of 100% of the duty. Run in Duty and Standby.

The room is around 3-5 years old. The evaporators are modern Techniblock 1000 A4523 fan evaps- the louvers are an add-ons. The condensing units have the same model number!?!

The issue is that we feel the louvers are hindering the operation of the room by directing the airflow in a straight line and reducing the circulation effect from the fans. I would like to remove to louvers but, I need to be sure that the is no advantage to keeping them.

Yes they close on defrost, but does that make them work better or keep th room cooler or make them more efficient. Is this just the folly of a mis-guided designer who got carried away with theories of no substance?

Your thoughts gentlemen please!