enviroguard Tyler rack
I have 5 racks with this type of system . I am not sure how to figure out what version of enviroguard it is and nor do i fully understand the concept tyler is implimenting.Here goes , drop leg comes down condensor tees off to an oldr going to the receiver and a solinoid in the liquid line going out to the cases. I see no subcooler in the systems. Also , there is a pressure regulator at the receiver, No hold back valve present( thinking the oldr is acting as a hold back valve). The oldr and the solinoid is being controlled by a t-stat that is on the drop leg of the condenser.Found some lit on this ,but is not sure if i fully understand.If anyone could brake this down to me it will be grately appriciated.
Would you believe me if I told you I worked with the guy who invented it and sold it to Tyler? No foolin. As a matter of fact I service the store where it was all drempt up and is the very first concept of it's kind. Still in it's original form and running. It was actually a guy who worked for my shop and he experimented with this idea at a store, and it worked. So he took the concept and sold it's patent to tyler.
Tyler Enviroguard is a way to reduce the refrigerant charge to the minimum possible.
Your working with Enviroguard 1. An SPR valve, attached to a liquid charged bulb up on the condenser. Of the same refrigerant as is in the rack. Think of the receiver as only a holding tank. Not a flow through receiver, and not a surge receiver.
Lets first tell you that, anytime 1 or more compressors is on, the solenoid valve opens on the receiver pump out, and it pumps back into suction. It's constantly returning anything in the receiver back to the system. You'll see that the pump out solenoid is piped along with a cap tube, so it flashes gas back to the suction manifold.
Now. We "dump" liquid to the receiver anytime the subcooling value gets greater than desired. Your removing refrigerant from the drop leg and "dumping" to receiver.
To best understand it with out a true explanation of how the spr does it, is to look at enviroguard 3. If subcooling rises above 14.9 degrees, we "dump" to receiver. The second that subcooling value drops, we stop the dump. All the while were returning liquid back to the system, but at a much slower rate.
Your piping is from condenser drop leg to liquid manifold. And we have a smaller bullheaded 1/2 or 5/8' line that we use for the dump. Taking liquid out of the system, and storing in the receiver.
If I have time tnioght I will dig out the pages on version 1 and post them so you can look at it. If I start talking about it, I will screw it up.
In winter, you'll see 0% receiver, and you should see a full column of liquid at the sight glass. In summer, your gonna see depending on ambient a receiver of between 5 and 35%. The hotter the ambient, the greater the receiver level.
Just understand, the receiver does not "flow through" or "surge". We dump to it and take from it. Based on subcooling. And in this way, we can drastically reduce refrigerant charge.
You are going to be a little confused for a while yet. The Envirogard System is very simple, but throws mechanics for a loop because it's so simple. Remember that subcooling can be made in different ways. You can "cool" the liquid below the saturated condensing temperature OR you can add pressure to a liquid that gains no additional heat and that creats a subcooled state.
Originally Posted by jaybee
The Tyler design has the large condenser and all the fans running like crazy because "the condenser is your subcooler". Most of the system high-side charge is in the condenser being subcooled. The idea is to run as much liquid as possible in the condenser and burp a little into the "surge receiver" if too much is being backed-up. As the ambient temperatures fall; the efficiency of the system increases and when it is "really too cold" outside; the pressure regulator acts as a minimum pressure regulator so you don't flood and bust pistons...
If your mind can throw out the existence of the reciever and run the flow stright to the liquid loop; you can see the vision of a critical-charge system. The surge receiver will only run about 8% when full during the summer. Being that once the system is set up, it is a critical-charge system; you can find the "case" in the circuit that goes down first on a lack of charge and alarm a low refrigerant notice from it. (almost 100% of the time; it is correct)
Go to Tyler Service Number and ask questions AFTER fully reading their manuals. They have evolved through a few changes in designs of regulators (SPR) to solenoid and so forth. You will need to get it all straight in your mind so you can be the guy that knows what he's doing...
I hope this helps a little and you get some enjoyment out of studying the design. In my opinion, for its class of design; it's one of the best I have worked with.
I did post a reply to the other thread you started on this topic.
Originally Posted by jaybee
About 10 years ago now I did one of my first Flash Presentations which just happened to be on the Enviroguard system. For about a year I was commissioning them at the rate of about 1 a week.
Have a look at this link...
The presentation even has setting instructions for the SPR Valve.
Remember, very importantly, these systems do not have subcool. They should never have subcool. the "quick diagram" states subcooled liquid but this is in reality not true.
Since these system float the head they require more refrigerant than a standard system - hense the side vessel.
Here is a copy and paste of my reply to the other thread you started...
The idea here is to float the head pressure and so drop the annual energy costs by up to 40% compared to a fixed head pressure system
This system is usually coupled with electric defrost because sometimes the head pressure can get so low the liquid line freezes - this means low heat-flux from the hot (or Kool) gas.
There is no subcooling designed into the system. Unless you use a liquid pump (Hysave LPA) you have to locate these systems a good few meters above all the evaporators and you most certainly cannot run your liquid lines up or even any significant horizontal distance before going down. Liquid lines generally must go down about 5m before going horizontal.
During summer and high load conditions there is greater flash gas in the evaps and so less liquid there and the warmer liquid in the liquid line expands and the liquid volumes collecting in the condenser tubes reduces and so the side vessel is used to store the excess liquid not needed for summer. During winter the velocity through the condenser slows and so liquid collects there, the cooler liquid in the liquid line is more dense (less voluminous) and there is less flash gas in the evaporator causing liquid levels there to increase which all leads to the need for greater system refrigerant charge in winter which comes from the side vessel.
There is a tube running from the SPR valve to a larger tube, normally with a sight glass, that is charged with the same refrigerant as the system, that sits outside the unit in the air-on but out of the sunshine. The SPR valve compares head pressure to ambient temperature via this tube system and if head pressure rises say 14K above ambient then it is assumed that there is too much liquid in the condenser, raising head pressure unecessarily causing greater power consumption, also starting to cause unwanted subcooling, and so the SPR valve opens to drain liquid from the condenser and into the side vessel.
A small continuous draining from the side vessel to the system suction via a discharge desuperheating heatexchanger takes place to ensure the system has more liquid available anytime as conditions change during the day and seasons.
One of the other advantages of this system is that it tells you very early on if you have a refrigerant leak. Case temperatures rise very soon after a small amount of refrigerant is lost.
Originally Posted by Dowadudda
Dowadudda, you seem to know a few things here, an interesting point that obviously requires a few conditions to be understood to be true is the reduced charge claim...
The link you give states "Reduces system refrigerant charge up to 45% and reduces refrigerant loss over the life of the system."
Reduced refrigerant loss over the life makes sense. But for the reduced refrigerant charge, well, if this were true then we would not need to have a side vessel for storing excess liquid in summer high load conditions. Nor would we have to add refrigerant when converting a system back to enviroguard from standard.
So I guess they must be comparing to, say, a koolgas defrost system?
Its interesting that they have worked on achieving year round subcool.
Originally Posted by Dowadudda
10 years back when I was commissioning these things we found that during warmer ambient temps and higher case loads the subcool would reduce to none, no subcool at all, and then it would rise nicely during winter and low case loads.
With all refrigerants, on account of the saturated P/T curve, for a given temperature change the pressure change is higher the higher the pressure. So at lower ambients the liquid had to fill up to 1/3 of the condenser before the SPR opened whereas during summer the condenser was always completely drained and so subcool was a problem - if you did not have a gravitational advantage. You could set the SPR's higher but then the energy auditor would catch you out for not reaching energy targets.
But the SPR principle does a great job of overcoming the problem of increased subcool requirements during low head pressures because of the P/T dP/dT ratio changes making the liquid otherwise more volatile.
Its a critical charge system, the last ones have subcoolers on the low temp rack using the med temp hp ( 2 stage, 2 -6 tons of subcooling) spr is maintaining 5 deg subcooling year round. the main liquid line sightglass should be clear at all times. One thing I did notice was the need to raise head pressure during heat reclaim mode. High discharge pressures are normal at high ambiant to create subcooled liquid. Do not overcharge system. At low ambiant the receiver should be almost empty. Using drop leg temp vs. drop leg pressure to maintain 5 deg subcooling . And yes there is an indicator, usually the furthest system will starve at undercharge conditions.
I guess I should refer to the receiver as a holding tank rather than a receiver as not to confuse the subject.
A few service techs pointers on the subject.
Last edited by frigeguy; 02-08-2009 at 07:27 AM.
Thanks gys this is really good info im just trying the digest this info so that i understand. Just for a clearing picture of components on the rack i was on , this rack has an oldr valve i am assumeming this is what is meant by (spr) the oldr is a no valve that is energized for diff mode and attached to this valve there a t-stat that is hooked to the drop leg.This stat is seta 100f and the valve is in diff mode.Dont really no if there is a ambiant sensor on the roof however these systems are controlled by comtrol.Also whenever i am back in the store i will look for the continuos bleed line to the suction. also will you please explain this statement
is usually coupled with electric defrost because sometimes the head pressure can get so low the liquid line freezes - this means low heat-flux from the hot (or Kool) gas. Tanks again for all the replies.
On sub freezing days we used to see the liquid line, as it comes through the roof from outdoors, actually causing the humid air in the store to not just condense on the liquid line but actually freeze. All the expansion valves were danfoss pulse type.
Originally Posted by jaybee
Awesome to have such an intelligent guy on board. Really. I think your contributions here are going to be hugely appreciated.
My company employed the guy who developed the enviroguard system. I still service the store where it was all drempt up.
Thanks for the vote of confidence, Dowa :-)
Originally Posted by Dowadudda
I understood it was two guys? Were they techs on the tools or maybe design engineers?
Get the rack numbers and call Tyler Service and order a service and operation manual for the rack. It pays off to get the right manual and stop the brainwashing.
If I recall correctly; the Sporlan OLDR is the DDR (defrost differential valve)
Are you sure that you're not working on an Equalizer Rack instead of an Enviroguard?
The Enviroguard loses a lost of points when gas defrost is opted...
Oh yeah; Marc - I disagree with you about the ratio of refrigerant weight to horsepower for the Enviroguard design. "In its class of design" I think that it is one of the most efficient designs for refrigerant use and loss risk-management.