# Walk-In Cooler Help



## mgraw (Jan 14, 2011)

Wirescraper said:


> The following is an e-mail I just sent to manufacturer, maybe I can get an answer from one of you guys first. THX.....
> 
> I'm wiring a few of your units, and have a couple questions. Are the Evaporator (In Cooler), and Condenser/compressor (On roof) typically fed from the same circuit? you've sent out a three phase 240v compressor (RLA 9.17) and the evap. is 1-phase 240v (7.8 fla). maximum fuse on comp. nameplate says 25a, and minimum ampacity of 20 . My plan is to drop off two phases of a 20 amp three phase circuit at the evaporator, and continue 3 ph circuit up to roof for comp./cond.. I assume 20a circuit should be enough to run these loads and I assume you calculate your max OCPD (fuse size) based on this Calc: Compressor 9.2 rla x 1.75 = 16.1 a .....16.1 a + 7.8 fla (evap coil) = 23.9 amps..........hence, max ocpd 25 for two pieces of equipment on same circuit. Is that correct? and should a 20 a breaker hold (25 amp breakers are hard to come bye).


Does the evaporator coil have some type of defrost? What other components does the condenser have? Typically I would use a separate circuit for the evaporator unless there is a reason to interconnect the evaporator and condenser.


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## aftershockews (Dec 22, 2012)

The first and only walk in cooler I wired years ago, I got with the HVAC guy and he drew me out 2 diagrams for me that I used to wire the coolers up.
Separate circuits for the compressor and the fans, a contactor above the walk in.


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## Wirescraper (Nov 27, 2011)

mgraw said:


> Does the evaporator coil have some type of defrost? What other components does the condenser have? Typically I would use a separate circuit for the evaporator unless there is a reason to interconnect the evaporator and condenser.


The freezer does have a defrost time clock currently located in the compressor unit on roof, Refrigeration guy who I cant get a hold of, mentioned moving timer into walk in freezer instead, to save me trouble with # of wires between units. Not knowing whether any of the wiring will intermingle between the two units, I almost feel like I should use same circuit, but real reason is breaker space in kitchen panel. Proj Mgr failed to remember that I have a high leg out here when ordering panel, not enough space. I believe the timer just shuts down the evap and starts defrost heater in some manner and condensing unit shuts down by a Pressure switch in its line that controls contactor coil once all that happens, not sure why timer would be in cond unit in the first place, maybe just cuz in cooler it's cold, icy, etc.. I'm no refrigeration guy, just want to pull wire now and not wait for refrigeration guy to show back up who knows when.


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## mgraw (Jan 14, 2011)

Wirescraper said:


> The freezer does have a defrost time clock currently located in the compressor unit on roof, Refrigeration guy who I cant get a hold of, mentioned moving timer into walk in freezer instead, to save me trouble with # of wires between units. Not knowing whether any of the wiring will intermingle between the two units, I almost feel like I should use same circuit, but real reason is breaker space in kitchen panel. Proj Mgr failed to remember that I have a high leg out here when ordering panel, not enough space. I believe the timer just shuts down the evap and starts defrost heater in some manner and condensing unit shuts down by a Pressure switch in its line that controls contactor coil once all that happens, not sure why timer would be in cond unit in the first place, maybe just cuz in cooler it's cold, icy, etc.. I'm no refrigeration guy, just want to pull wire now and not wait for refrigeration guy to show back up who knows when.


 I would leave the clock in the condenser and feed power to the fans, defrost heaters and t-stat from there.

The cooler would be different. I would feed a separate circuit for the fans. If there are not any 120v components on the evaporator you could use the high leg and another circuit to feed it.


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## Wirescraper (Nov 27, 2011)

Answer me this...on the compress/cond unit nameplate it lists rla of 9.17 for compressor, 1 fla for cond fan......it also lists evap fan mtr max amps of 7 a, also defrost htr max amps of 15 a. On the comp unit nameplate it lists all this equipment even though the evapor fan/defrost htr is seperate equipment, on the nameplate it reads max ocpd of 25a, min ckt ampacity 20 a (for wire). So answer me this, why list seperate equipment loads on nameplate if not intended to be on same ckt, all together. The only thing I fear is that they reached their max ocpd # of 25amps by taking the 9.17 rla x 2.25 (exception when bkr trips at startup) + 1 a for cond fan = 21.6 a....25 a ocpd, which would mean I'm wrong in assuming they intend all equipment on one ckt....so then I'm an ass and get to redo everything.


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## Wirescraper (Nov 27, 2011)

Do you typically run the two on same circuit or separate circuits, just answer that


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## bkmichael65 (Mar 25, 2013)

I've only done a couple of coolers, but I ran ran them on separate circuits


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## hardworkingstiff (Jan 22, 2007)

It's been 20 years since I wired a cooler, but IIRC, the evaporator coil fans were on a circuit by themselves and ran all the time. The condenser was on its own circuit and controlled by a T-Stat in the cooler. These were C-store units.

That doesn't mean your unit is wired the same, when you find out how the manufacturer wants you to wire it, please let us know.


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## mgraw (Jan 14, 2011)

Wirescraper said:


> Do you typically run the two on same circuit or separate circuits, just answer that


 Freezer same circuit, Cooler(if no defrost element) different circuit.


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## Deep Cover (Dec 8, 2012)

The last ones I did, fans and compressor on the same circuit. We just had to hit the compressor with power, then there was a premade whip to run to the fans.


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## Wirescraper (Nov 27, 2011)

mgraw said:


> Freezer same circuit, Cooler(if no defrost element) different circuit.


I'm just wondering, why not with the cooler? The cooler seems like a no brainer for same circuit, the evaporator load with no defrost is going to be negligible. For instance, the cooler out here has evap coil 115 v 1.8fla and compressor 230 v 3 ph at 4.2 amps. I was going to for sure just drop off a leg and a neutral(not the high leg) at the cooler and continue the 3 phase circuit up to the condenser, the condenser nameplate for the cooler says 20 a max ocpd, so I'm almost positive there's no issues with combining circuits for the coolers, its the freezers im not too sure about.


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## wendon (Sep 27, 2010)

If it's a freezer the defrost heaters usually are controlled at the condenser. There should be a timer and, if it's a larger unit, a contactor to feed the defrost heaters. The fans probably are fed from the condensing unit also. Usually they install a liquid line solenoid next to the evaporator. On most units like this when the defrost is initiated, it shuts off the liquid line solenoid, shuts off the fans, and powers the defrost heaters. If it has a contactor for the defrost heaters, it may be disabled until the condenser has pumped down and shut off. When the temp sensor on the evap coil warms up to the preset level it terminates the defrost and starts the fans. Different units may have variations but most of them are similar. If it's a small unit, the defrost heaters will be fed through the defrost time clock. Leave the timer in the condensing unit. It's much nicer to work on it there than in -20 degrees.


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## farlsincharge (Dec 31, 2010)

Cooler is easy. Use the same circuit if you want or separate circuit if it is easy. Remember there is probably a light as well.

Freezer, the fans have to be run on the timeclock, so do the defrost heaters, and the power for the solenoid.

Run a separate circuit for your lights and thermostat, so that they do not go out in a defrost cycle.


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## Wirescraper (Nov 27, 2011)

farlsincharge said:


> Run a separate circuit for your lights and thermostat, so that they do not go out in a defrost cycle.


The lights for the coolers and freezer as well as the heat tape in the freezer, I do plan on having all together on a single separate circuit. I just can't afford 4 breaker spaces (3 for comp and 1 for evap) for the cooler equipment and 5 breaker spaces (3 for compressor, 2 for evap) for the freezer equipment, I can afford two 3 phase circuits, unless I have no choice and then other stuff gets combined.


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## wendon (Sep 27, 2010)

Wirescraper said:


> The lights for the coolers and freezer as well as the heat tape in the freezer, I do plan on having all together on a single separate circuit. I just can't afford 4 breaker spaces (3 for comp and 1 for evap) for the cooler equipment and 5 breaker spaces (3 for compressor, 2 for evap) for the freezer equipment, I can afford two 3 phase circuits, unless I have no choice and then other stuff gets combined.


I don't know if it'll work but how about if you install a breaker or fuses in the condensing unit to feed your evaps?


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## MHElectric (Oct 14, 2011)

Im not the most code savy just here, but if your tight on breaker spaces in the panel, isn't there some tap rule that you could use here to get by with just one breaker sized large, and then put fused disconnects at each peice of equipment?

Maybe im wrong, but thats the first thing I would look into to keep from accidentally putting too much on one circuit.


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## CADPoint (Jul 5, 2007)

*Hope something hekps here.*

I just spent a long time in a lot of walk-ins, just the past year. We worked for the supplying vendor which itself was an eye opener. We ran all circuits seperate expect lights and heat tape receptacle but itnwas two circuits. Now we ran all this from a controller that contained all the fuses for everything. So our set up was way different that just a stand walk in!

So four sets of pipes one for receptacles (no requiered in your case) one for control, lights with heat tape and one for power for both units. Everything had their own circuit.
the thermostat was just on the other side of the wall. We drilled throw. One has to be sure exactly what size of belden wire to use we used 14 and 18 on controls and thermostat.

Are you sure that there isn't a door heater?

Here's what we did. We entered from the top on all penetrations. On these drops we soaked plastic threaded pvc fittiing s five inchs long, with silicon, you can fine these at big box. We'd run heat tape and wall receptacles all we inside the walls. We drilled down to enter all equipment. The vendor had to drill out the vertical walls. Inside was enough to except either a 1/2" or .3/4" rigid coupling and change over to emt. We used both "L 's " and 4 sq (deep it was spec 'd.)
We 'd silicon every penetration made then again on the inside and outside and both top and bottom.

You might also see if an alarm is required if lockable.


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## gold (Feb 15, 2008)

Seperate circuits. Move the defrost timer to just outside the walk in door and run a conduit between it and the evaporator. The clock terminals will correspond with the evaporator terminals. The solinoid and t stat comes right off the evap. No need for contactors. You will also need heat tape and lighting ckt. Possibly a door heater ckt.


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## wendon (Sep 27, 2010)

Goldagain said:


> Seperate circuits. Move the defrost timer to just outside the walk in door and run a conduit between it and the evaporator. The clock terminals will correspond with the evaporator terminals. The solinoid and t stat comes right off the evap. No need for contactors. You will also need heat tape and lighting ckt. Possibly a door heater ckt.


You could do that on a cooler as it is usually air defrost but I wouldn't do it on a freezer. On most walk in freezer units the defrost heaters are fed from the condensing unit. There would have to be a door heater.


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## Bbsound (Dec 16, 2011)

I have done sep circuits. I have done about a dozen or so.


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## gold (Feb 15, 2008)

wendon said:


> You could do that on a cooler as it is usually air defrost but I wouldn't do it on a freezer. On most walk in freezer units the defrost heaters are fed from the condensing unit. There would have to be a door heater.


Not all freezers have the defrost heater but I did make some assumptions based on his OP. He didn't mention the heater load. I've also seen some of the newer units with the heaters fed right from a contactor in the evap and the coil is fed from the defrost timer. But your right I made some assumptions that this is a smaller walkin with the freezer in the back and no defrost heater.


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## wendon (Sep 27, 2010)

Goldagain said:


> Not all freezers have the defrost heater but I did make some assumptions based on his OP. He didn't mention the heater load. I've also seen some of the newer units with the heaters fed right from a contactor in the evap and the coil is fed from the defrost timer. But your right I made some assumptions that this is a smaller walkin with the freezer in the back and no defrost heater.


The last freezer I installed had the defrost timer in the condensing unit. The defrost contactor was powered by the defrost timer. It also went through a NO aux contact on the contactor for the compressor. That insured that the defrost heaters and the compressor would never run together. If it's a freezer it either has to have a hot gas defrost or resistance heaters in the evap coil. Otherwise the ice will build up.


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