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Thread: Tyler Rack
12-20-2010, 06:26 PM #1
I was working on a tyler enviregard rack today (repairing a leak) and noticed that there was no hold back valve on the dropleg! I looked for the ord valve and it had what looked to be a solenoid valve with a coil comming from the discharge to the reciever! It looks as though there was never a holdback installed from the manufacture! It got down to around 15* the other day and this rack was running fine 200psig head. Is it possible they are just measuring the reciever temp. and when it drops engergizing this valve and pressurizing the reciever? Its a r404a lt rack.
12-20-2010, 07:33 PM #2
The receiver in an enviroguard set up acts like a surge tank.
The controller measures the value of the sub cooling on the drop leg. If the subcooling rises, the refrigerant dumps to receiver until sub cooling falls below the sub cooling set point. All the while, if any one compressor is on, the refrigerant in the receiver slowly meters back into the suction header through pump out arranegement with a cap tube.
Basically, we take refrigerant out of the system to store in the receiver when it is not needed. In higher ambient, the receiver will be at 10, 20 or 30% depending on an ambient of 70,80 and 90 degrees respectively. In lower ambient refrigerant will not be in the receiver, you will see it stacking in the condenser, thus the reason for the higher head. By stacking liquid this way, it sort of in a round about way acts like a hold back would. It floods the condenser.
There are a few thresholds. If below a 30 degree ambient for example. I am possibly going to have a decent amount of sub cooling. But I need that liquid for stacking. I will not dump to receiver if liquid sub cooling is above sub cooling set point, but I am below 30 degrees ambient. There is a decent amount of scenarios and situations that have to be accounted for on a rack like this, and they had 3 different versions, all with a little twist on the previous version. It's too long to get into.
I worked with guys, who had at one time worked with the guy who designed and patented this system who then sold it to Tyler. No foolin. A service technician developed this.
What was it's intended purpose? Reduce refrigerant charge. Gain efficiency with the use of low ambient."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
12-20-2010, 07:46 PM #3
I have a danfoss AK2-SC255 controller can i mount the sensor to the dropleg and wire the solenoid (ORD) or whatever they call it to the output and have it energized at say 12 or 14* subcooling? How does it stack the refrigerant in the condenser? there is no split valve?
12-20-2010, 07:50 PM #4
you need to study up on the enviroguard first, then you will know yourself. This is one of them things where, you got to put the work in to do it.
You can screw this up with out being somewhat familiar. There is a plenty of info out there to get boned up on this."The only real security that a man can have in this world is a reserve of knowledge, experience and ability." Henry Ford
12-20-2010, 07:59 PM #5
I appreciate the info there is no sensor on the dropleg currently. I am concerned that once it gets colder and stays cold going to have some issues! This rack was just installed in the spring. Do you know where i can locate the step by step setup for this strategy? Or would installing a holdback and ord work on this system?
12-20-2010, 08:19 PM #6Professional Member
- Join Date
- Jul 2008
- Nova-Scotia, Canada
12-20-2010, 09:18 PM #7
There are no sensors comming from the danfoss controller they are only useing it for compressor staging and cycling the condenser fans. This rack was definatly not installed to operate the way it was manufactured to do! I'm trying to find out exactly how the low ambient setup is designed to operate and make it so or if it would be more feasible to install a holdback valve and ord and just do away with the initial setup!
12-20-2010, 11:15 PM #8
for starters take a look!
Sig removed by mod. G-Rated site
01-05-2012, 05:57 PM #9Professional Member
- Join Date
- Dec 2011
The newest version of Danfoss AK2 controllers have an option to setup the enviroguard. Just tell it it has a enviroguard and it will give you the inputs.