Proper or Recommended setting for walk-in Mechanical Defrost Timer

Joined Feb 8, 2017
Not really sure where to post technical questions, hope someone can help.

First the question:  

Does anyone know the recommended settings or how to come up with recommended settings for the Mechanical Defrost Timer in the walk-in.  Currently it's set to turn on at 8:00am and 8:00pm for 30 minutes.

The Background:

We purchased our catering company a few years ago and while everything is working, like with any "used" purchase it's hard to tell if things were setup correctly even though they seem to be "working"  

So we recently had an issue with the Electronic Temp Control unit in our walk-in and when I went to replace it, I learned we had a Mechanical Defrost Timer.   

A brief review of the manual online and it appears any time we've had a power outage, I should have reset it to the correct time.

So here's the thing.  I don't think anyone has ever set it to the correct time before, except maybe 10+ years ago when it was installed.  That's a lot of power outages ago...

So I'm trying to figure out what the best time of day it should be set for based on what.  The manual is great for telling you how to make the settings, but not recommending them.   We don't have ice buildup so I assume the two "on" periods at 12 hour interval for 30 minutes is fine, but now that it's set for the correct time...   the unit is OFF and being "DEFROSTED" right when people are walkling-in and out of the unit the most.

We noticed that now that it's set to the correct time, it as expected loosed heat a lot faster because it's off at "peak" usage time for a little bit.

I'm thinking...  maybe switching it to 6am and 6pm as no one is really around at those times?  

Any thoughts? Input? Guidelines? Rules of Thumb?   I've googled the daylights our of the topic, but I just keep finding instructions on how to set it to what I want....  not how to decide what is best.

Thanks in advance
Joined Oct 10, 2005
Many timers go on a 20 min cycle every 8 hrs.  The reason for this is that the coil (that box inside the walk in) gets plugged up with ice.  Every time you open the door, warm air enters the box where  it invariably meets the coil.  warm air + cold air= condensation, + cold air= ice.  The more you open the door, and the warmer your ambient temp is outside the walk in, the more ice will form on your coil.  If the coil gets so plugged up with ice, it can't perform properly and the whole unit will shut down. 

So, what are your peak times in using the walk-in?  Lets say the prep guys are opening the door constantly from 9-11 am, then again from 12-1.  So a good time for the unit to shut down and defrost would be 2 pm -2:30 pm.  Again, peak time for the dinner guys would be 3-5, with occasional running in from 6-8, so the best time for defrost would be 9 pm - 9:30 pm.

Hope this helps
Joined Feb 8, 2017
Thanks,  that makes a lot of sense actually..  For the most part, ours is a swinging door from around 8:30am - noon, maybe a bit longer on some days so by 2pm we're generally quiet again.  Then if there is an evening event, somewhere between 10pm and 1am will be active for a bit as they put stuff away, so 2am would work.

As I said, the every 12 hour for 30 minutes has been fine for years, so I don't really wanna mess with what isn't broke.  Not sure why they ever set it at 8am and 8pm cause based on your description, that's kinda pointless for us.

By the way, the photo above is our actual unit.   

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