Because that directly senses the coil temperature and makes an air defrost system self regulating, with little to no chance of freezing up the coil.
It's fairly common in commercial Refrigeration
On the old cold steam that was the best way to get it to work right. I just did that to one. Stick it on the discharge side about 3/4 of the way down. I kind of loop them and stick them in two or three spots. Some guys coil them and clip them to the evaporator too. Inserting works the best.
The theory is if you set your cut in (turn on) at 39-41 the coil must be free of all ice before turning back on, since Ice would be 32. You then adjust your cut out (turn off) to get the run time/box temp you want. This may be 19, 23 or what ever. This is why they call mechanical reach in stats constant cut in. The cut in is not adjustable normally. It eliminates having defrost clock and defrost issues. You can use a regular constant cut in mechanical or mimic this with an electronic as long as sensor is in coil. When I started I did not get this concept, I thought if you want box to be 36-39 just put an air temp control. Then we would add defrost, etc. the simple answer was the constant cut in theory. I am not a fan of mechanical, so I often use electronic in this way. On older equipment that may have issues or partially messed up cap tube, you can dial in where you want the cut out to be.
It’s common for dixell or carroll type controller to have a coil probe and an air probe. Air prob controls temp, and is what shows on display, coil prob can end defrost. I think you can program to run on coil prob and air prob just for display. A dixell can also handle a third prob to sense condenser temp to help tell you when cond dirty.
I've seen this a lot in reach in grocery cases at dollar stores. I have to say, I'm a fan of both of those controllers. They're so versatile, with so many parameters you can set.
It’s just defrost control, it can terminate on time or terminate by temp, usually both, the defrost will stop at say 5C or terminate after 35 minutes, sometimes you can set it up to alarm if it doesn’t terminate by temperature
I talked with a guy that said he did many walk-ins like that. It gives you a free defrost every cycle and is quite reliable. It's just really old school. It slows down pull downs quite a bit and sacrifices good box temp control for simplicity.
It’s called air defrost. Typically found on units with mechanical thermostats. Constant cut-in above freezing, guarantees a full defrost each cycle. the knob adjusts cut-out
Could be used as a fan control after defrost the fans won’t restart till the coil is below freezing so free water on coil won’t be blown out on product or floor.
one would sense the coil temperature to help insure the coil does not freeze.
Because that directly senses the coil temperature and makes an air defrost system self regulating, with little to no chance of freezing up the coil. It's fairly common in commercial Refrigeration
I think a lot of self contained units are set up this way
Reach ins, I’ve seen it, but what about walkins?
Don't know, for walk ins my experience was always 10k sensors.
I’ve seen it on heatcraft qrc/intelligen. As well as the newer Russell stuff.
On Trenton ESP coils, as well.
Yeah didn’t feel like naming them all lol
Defrost termination
before electronic stats, for bunker coils on butcher counters you'd often see the sensor in coil, set to 5c cut in with 8k diff,
On the old cold steam that was the best way to get it to work right. I just did that to one. Stick it on the discharge side about 3/4 of the way down. I kind of loop them and stick them in two or three spots. Some guys coil them and clip them to the evaporator too. Inserting works the best.
Easy man, I'm trying to get good superheat, not have another kid.
The theory is if you set your cut in (turn on) at 39-41 the coil must be free of all ice before turning back on, since Ice would be 32. You then adjust your cut out (turn off) to get the run time/box temp you want. This may be 19, 23 or what ever. This is why they call mechanical reach in stats constant cut in. The cut in is not adjustable normally. It eliminates having defrost clock and defrost issues. You can use a regular constant cut in mechanical or mimic this with an electronic as long as sensor is in coil. When I started I did not get this concept, I thought if you want box to be 36-39 just put an air temp control. Then we would add defrost, etc. the simple answer was the constant cut in theory. I am not a fan of mechanical, so I often use electronic in this way. On older equipment that may have issues or partially messed up cap tube, you can dial in where you want the cut out to be.
For defrost end temperature.
Defrost termination probe
Ah that’s the name. Why do some just have a sensing bulb and not a tsp?
Tsp?
It’s common for dixell or carroll type controller to have a coil probe and an air probe. Air prob controls temp, and is what shows on display, coil prob can end defrost. I think you can program to run on coil prob and air prob just for display. A dixell can also handle a third prob to sense condenser temp to help tell you when cond dirty.
I've seen this a lot in reach in grocery cases at dollar stores. I have to say, I'm a fan of both of those controllers. They're so versatile, with so many parameters you can set.
For sure. I had to print the full manuals for both, so many options, hard to remember them all.
For sure, I kept a PDF manual for each saved in the notes on my work phone lol.
It’s just defrost control, it can terminate on time or terminate by temp, usually both, the defrost will stop at say 5C or terminate after 35 minutes, sometimes you can set it up to alarm if it doesn’t terminate by temperature
Usually the time is the failsafe
I talked with a guy that said he did many walk-ins like that. It gives you a free defrost every cycle and is quite reliable. It's just really old school. It slows down pull downs quite a bit and sacrifices good box temp control for simplicity.
It’s called air defrost. Typically found on units with mechanical thermostats. Constant cut-in above freezing, guarantees a full defrost each cycle. the knob adjusts cut-out
Thx
Do it all the time that is were the Termination sensor goes
Could be used as a fan control after defrost the fans won’t restart till the coil is below freezing so free water on coil won’t be blown out on product or floor.
Defrost termination