sub-zero walk-in frosting

[Aircooled81]

My walk in is not dehumidifing quick enough. I put in a new evap and condenser for a 0 to -10 walk in freezer about 6 weeks ago. I resealed the walls while the temp was up, and gasketed the walls. I'm still working on the door lining/gasketing. Infiltration of heat is now much less then what it used to be.
The kitchen staff blocked off the evap last week, temp climbed to 8 degrees and I got called back. I had about the top 3rd of the evap coil Iced-up. This freezer by the way enters from a walk-in frig (35-41). I had no choice after trying to reset the defrost schedule (electric strip) and it wasn't able to melt all the ice down over a day and a half - to taking a heat gun and manually thawing it out. Well, all the steam in the room had no where to go, and It iced up again 4 days later. I checked the equipment for running conditions, I have a full sight glass up at the condenser, 8 degrees sh at the evap, and 24 degrees comp sh when the unit is thawed. I set the defrost sched to 6 defrosts at 30 min a piece in hopes to ring out more moisture.
Am I on the right path?

[rayr]

Yes. Butttttttttttttttt, make sure the time delay for the fan is working keeping it off till the coil is cold. Also, what is the composition of the box??????

[tjc76]

like rayr said, check the fan delay and termination. check to make sure all the defrost heaters are working (put your amprobe around each heater). make sure that the time clock is working and keeping proper time. make sure that the unit pumps down when the liquid line solenoid is deenergized. does the box ever reach temperature? is x hooked up to the timeclock? what is the clock failsafe setting? is the termination/fan delay a klixon, or is it adjustable? also, manually turn the timeclock into each defrost period and make sure that defrost energizes(do this with x disconnected) in each period. i have had 8145 clocks that do not energize defrost with every pin.

[Aircooled81]

fan does de-energize when the unit goes into defrost (i don't know how soon or for how long), and has a delay before they come back on once the llsv opens. I haven't checked every pin on the defrost timer, and will do so on thursday. Composition of the box? - It's 6wx8hx10d, 3 inch walls, filled with 3 shelves of basic kitchen meats, ice creams, fruits and vegetables (bagged), and is opened quite regularly throughout the day.
I amped out both heaters today, they are both running fine. The box does not reach temp during the day, only in the early am and in the evening, it does hang out around -8 to -2 throught the day and climbs to 45 on a 30 minute defrost ( damn!). the pins are 15 minute incraments. this temp climbing above 32 may be the cause for the moisture level climbing so quick.
i don't know the timeclocks termination setting. I can check that on thurs.
this morning it was -2 in the box, it had gone through defrost 2 hours prior, and the coil was frosted, but the puddle of ice at the top had not reapeared.
russell had recomended 4 defrosts at 30 minutes, I currently have 6 at thirty minutes to try better dehumidification, what do you think about multiple 15 minute defrosts.
thank you for your replies.... good stuff to check.

[r404a]

unit oversized? Don't think so if it only pulls down in am. How about drainline trapping?

[r404a]

unit oversized? Don't think so if it only pulls down in am. How about drain line trapping? Could this be causing issues?

r404a

[Slatts]

Does the unit pump down on defrost or does it drop the compressor and LLSV at the same time? You'll get a better defrost if you do it this way. By leaving the refrigerant in the evap it helps to distribute the heat from the defrost heaters. 30 minute defrost for an electric defrost seems very excessive to me.
When you defrosted the evap did you shine a light through the coil to make sure the core was clear?

[Aircooled81]

i hope to get back out there on thursaday,
i like the idea behind the evap holding a charge to distribute the heat in defrost, it is currently a pump down system.
the drain has no trap, the pan however does not pool up to a full pan, it just has minor puddles and still drains. the heater for the drain line is new and works fine too.
the core was clear, i shined a light through the fins, and could see it on the other side, I did however have water drops dripping down which I chose to only wipe off the face of the coil and fan blades, but couldn't dry the whole coil inside and out.

thank you for the ideas, I'll be glad to try alot of these out tommorow and give you guys a good recap

[Slatts]

i hope to get back out there on thursaday,
i like the idea behind the evap holding a charge to distribute the heat in defrost, it is currently a pump down system.
the drain has no trap, the pan however does not pool up to a full pan, it just has minor puddles and still drains. the heater for the drain line is new and works fine too.
the core was clear, i shined a light through the fins, and could see it on the other side, I did however have water drops dripping down which I chose to only wipe off the face of the coil and fan blades, but couldn't dry the whole coil inside and out.

thank you for the ideas, I'll be glad to try alot of these out tommorow and give you guys a good recap
Air if you look at the drawing I attached to the last post you'll see the system is still a pump down system except on defrost.
A bit of water on the coil won't hurt. If the fan delay is set up properly it'll freeze before they start.
I'd advise fitting a trap external to the room to stop moisture being sucked up the drain

[local 832s]

If the drain isn't trapped, infiltration is going to be a problem.

[town]

like rayr said, check the fan delay and termination. check to make sure all the defrost heaters are working (put your amprobe around each heater). make sure that the time clock is working and keeping proper time. make sure that the unit pumps down when the liquid line solenoid is deenergized. does the box ever reach temperature? is x hooked up to the timeclock? what is the clock failsafe setting? is the termination/fan delay a klixon, or is it adjustable? also, manually turn the timeclock into each defrost period and make sure that defrost energizes(do this with x disconnected) in each period. i have had 8145 clocks that do not energize defrost with every pin.
What is the basic TIME CLOCK set ? please Sr.