Day/Night Temp Control

[Azeotrope]

Just thought I'd share some pics of the Day/Night Temp Control panel that I just put together. Had this all functioning already, just cleaned it up with new gear and put it in a box.

Just two electronic T-stats that cycle the compressor on and off (this is a commercial single door freezer cab). One is active all the time and set for day time temp and the other is wired in parallel with it and set for night temps but there is a time clock that breaks that control circuit to lock it out durring day (lights on). This allows me to set the lower or night temp to run an hour in to the lights on cycle and start an hour before lights off cycle.





Now to install the little bugger......... I also have an electronic humidity sensor/control with a relay that I need to wire up (24v) so I can add a relay to this box and cycle on the compressor when RH exceeds desired.

 

[lee van keef]

Badass.

 

[noyd666]

very clever, neat instalation.

 

[Azeotrope]

Thanks folks. Was going to install it tonight, but the beat-up knee is begging me to rest for a night and do it tomorrow.......

 

[Azeotrope]

Okay, got this installed, temp probes calculated and everything on-line.... Got a few hours of sleep and awakened to find my ladies at 121F !!!! I should have seen this coming. I had wired the time clock to break power to the night/dark period t-stat and it's contact set. Perfect. These A419 t-stats have a built in 'anti short cycle time delay' that I set at 3min. However, I had the day tstat active "hot" all te time figuring that it's setting was higher than the night, so no fighting and all would get along.

Not sure when, but at some point, probably at the 8am switch over to night temps, we short cycled the comp and it tripped it's overload. So now the time clock breaks power to each t-stat and their respective contacts when it is not their time. Cab is now 65F for night cycle. Going to watch the switch to day/lights-on very closely in 12hrs and the next switch over 12hrs after that.

Not often that I don't have this stuff thought out more thoroughly! What I had installed previously was not as clean and compact, but worked like I have it wired now...

Hope the girls will forgive me.

 

[rives]

Don't you just love those forehead-slapping moments? What is the manufacturer of the T'stats? I don't recall seeing any that were DIN mountable.

 

[Azeotrope]

Yeah, for years I have been gutting old controls and EMS system panels and updating with the latest and greatest. This with the objective and freedom to custom commission large industrial and commercial systems for the best operational performance, energy efficacy and reliablity. Most of the time with many thousands if not close to $1million in food still in the fixtures. In total over the years I have suffered a total product loss of $1,800.00 dollars! Last night, I got home from a long week and crazy day, pulled out the tools and threw that together in a matter of about 45min. Did not stop and really think about it to much..... It was old tech to me and too simple!LMFAO!!! And that is exactly what will get a person! Cocky and complacent! I preach this to techs from my office most days and when I am doing this for a customer (less often these days), I focus like a lazer and it is very second nature.

After I got over the steam cloud that came out of the cab and re-wired everything quickly, I had to chuckle..... A little damage to a couple of tops and some stress to the girls, but all-in-all no loss of life or limb. Plenty of clones waiting and some beans I need to try so at worst I would be set-back a few weeks.

Those are Johnson Controls A419s. They can be fed with either 120 or 208/240v and have a SPDT relay. They have quite a bit of adjustability and have been very reliable for us in the field over the years. Sensor cable can be extended to 300' with 18/2 Belden type.

Full part #A419ABC-1C

Available in 24vac as well.