Complete repair, installation, and service of walk in coolers and walk in freezers

Walk in coolers
Walk in freezers
Walk in floral coolers

 

WALK-IN COOLERS AND FREEZERS: CONSUMER INFORMATION:

 

At its most basic, a walk in cooler or walk in freezer is nothing more than an insulated compartment

with the appropriate refrigeration system to maintain the desired internal temperature and/or humidity

level. 

 

We will be discussing walk-in coolers and freezers which are modular, meaning they are constructed on

site from insulated panels with a metal skin, and are joined together by "cam-locks" which are pre-built

into the sides of the panels, allowing them to be joined together from inside of the cooler or freezer with

nothing more than an Allen wrench, which is usually supplied with the panels.

 

 

 

PANEL CONSTRUCTION TYPES:

 

There are four main types of panel construction in use today for walk in coolers and walk in freezers.

 

1. Foamed in place: (Frameless) The two metal skins are placed in a mold, and the urethane compound is blown, or "foamed"

into the mold with a blowing agent, either R-134A or Pentane. The only thing attaching the metal skins to the insulating material,

is the "gluing" or adhesive properties of the blown in urethane compound as it sticks to the inside of the metal skins as it dries.

In this tye of construction, the panel is not put in a press as with "soft nose" panel construction, (See 3.), so foaming rate,

blowing agent ratio, and prepartion of metal skins is very critical to prevent air pockets.

Gaps, cracks, and channels can be incorporated into the panel insulation without carefull attention in the manufacturing process to

quality control. Since it is not place in a press, delamination of the metal skin can also be a problem with this type of panel construction.

 

2. Foamed in place: (Wood frame construction) In this type of panel there is a wooden frame constructed of inexpensive

pine or fir "2x4's". 

In this type of panel you have a wooden frame with insulating material in the center of the wooden frame.

The metal skin is typically crimped over the edge of the wooden frame and attached to the wood by staples.

The tongue and groove on the edges of the panels are formed from the same wooden frame, so that you have

wood mating to wood when the panels are put together.

A "2x4" is actually nominally 1 1/2" x 3 1/2", so when you see a panel that is 3.5" thick, it is usually a wooden framed panel.

Wooden framed panels are inexpensive to manufacture and are a popular panel with manufacturers for this reason.

The only advantage of wood frame construction for the owner is good structural strength provided by the wooden

frame portion of the panel. This could be important for large ceiling span lengths in outdoor conditions subject to a

heavy snow load for instance.

Their are several important problems with wood frame construction:

a. Wood has a very poor R-value, (ONLY A LITTLE OVER R-1 PER INCH), so the panels overall R-Value is greatly

reduced by the wooden frame, regardless of what type of insulation is used in the center of the panel.

b. Wood, when subject to constant moisture as the result of condensation, as you have in a walk in cooler or freezer

application will eventually rot.

c. Wood under these conditions also commonly develops black mold.

 

3. High Density Rail: (Not to be confused with "Foam Rail") The highest performance possible with a

"foamed in Place" panel.

This type of panel has advantages of both the soft nose and wood framed panels.
Its main drawback is its price, which is higher than wood frame or soft nose panel construction.

In this type of panel, the frame is composed of high density urethane or polystyrene "boards". The density of urethane 

used in the insulating portion of a urethane insulated panel is about 2.2 lbs per board foot. The high density frame portion

of a high density rail panel is about 8 lbs per board foot. The higher density required for the rail portion of the panel

sacrifices some of the panels R-Value, since with urethane or polystyrene, the higher the density, the lower R-Value.

In this type of panel you have the high structural strength of a wood framed panel, without sacrificing the insulating value

of the panel as with wood frame construction.

In this type of panel, you have both a chemical, (adhesive), bond between the metal skin and insulating material, and also a

physical structural attachment between the metal skin of the panel and the panels insulating material.

For walk-ins requiring a floor subject to heavy weight loads, such as pallets, this type of panel construction is superior.

Another advantage is that High Density Rail panels are not subject to rot as wood framed panels are.

 

4. Soft nose construction: An excellent comination of performance and price. In this type of panel there is no frame per se. The metal skin is formed around the edges

of the insulating material, with a thermal break between the two halves to maximize it's insulating ability.

This type of panels core is composed of solid sheets of insulating material, (either expanded polystyrene of varying densities,

urethane, or extruded polystyrene, so air pockets, gaps, channels and cracks cannot occur as with "either type of "foamed in place"

urethane panel construction.

In soft nose panel construction, unlike "foamed in place" the panel is placed in a press to ensure a positive bond between the metal

skins and the insulating material.

In this type of panel, the tongue and groove is formed from the insulating material itself, so that you have insulating

material mating to more insulating material. This type of panel gives the best insulating value.

It has a lower structural rigidity than a wood framed panel, which could be important on wide

roof spans when subject to snow loads in outdoor applications.

 

 

PANEL SKINS:

 

1. Stainless Steel: Very corrosion resistant but also very expensive. A major drawback is that it easily shows smudges

from hands and fingers, and is not easy to keep clean.

(Never clean Stainless Steel with "bleach" or solutions containing "bleach", as the active ingredient in bleach, Sodium

Hypochlorite is highly corrosive to Stainless Steel.)

2. Acrylic Coated Galvalume: Second only to Stainless Steel in corrosion resistance, unlike Stainless Steel it is very

resistant to smudging and is easily kept clean because of its Acrylic coating. 

Galvalume is 12 times more corrosion resistant than G 60 grade galvanized steel and 6 times more corrosion resistant

than G 90 grade galvanized steel.

Its main drawback is that it is more expensive than G90 or G60 grade galvanized steel.

Same as Galvalume below except for its Acrylic coating.

 

3. Galvalume and Galfan: Both are composed of steel that has been plated with highly corrosion resistant aluminum

and zinc compounds.

This combination gives the material both rigidity and dent resistance as well as excellent corrosion resistance.

It has a flat Silver appearance and is usually embossed.

 

4. Aluminum: Very resistant to corrosion except for saltwater environments or use in dairy applications where the

Aluminum will come in frequent contact with milk or other dairy products containing lactic acid. It is somewhat more prone

to denting than Galvanized Steel or Galvalume.

 

5. G 90 Galvanized: Probably the most commonly used skin for walk-in coolers. While not as corrosion resistant

as Galvalume or Stainless Steel, it is less expensive. 

The "90" in G90 describes the quantity by weight per square foot of corrosion resisting zinc coating.

With Galvanized steel, the greater the amount of zinc the greater the protection against panel corrosion.

Two commonly used Galvanized steels are designated as G90 and G60. These designations relate to the total amount of

zinc compounds per square foot of area.

G90 contains 0.9 ounces of zinc for every one square foot of panel while G60 contains only 0.6 ounces of zinc.

The important fact to consider is that G90 contains 50% more protective zinc than G60 substrate.

This difference will have a direct correlation to panel longevity and long-term aesthetics of your cooler or freezer.

 

 

6. G 60 Galvanized: LOWEST CORROSION RESISTANCE OF ANY METAL SKIN! PLEASE READ MORE NEXT TO G 90

ABOVE

 

 

 

TYPES OF INSULATING MATERIALS:

 

Expanded Polystyrene (EPS): This well proven insulating material starts as solid beads that are expanded into

conjoined foam beads through the use of heat in the form of steam.

This material comes in two densities, normal density (about 1lb per square foot), which is suitable for cooler applications,

and high density (about 2.25lbs per square foot), which is needed when being used for a walkin freezer application.

The millions of tiny cells which result are filled with air, which give polystyrene its low thermal conductivity.

It has a very stable R-Value and a very good resistance to moisture penetration as can be seen through its widespread

use as a flotation material. Unlike urethane insulation, it loses very little of its R-Value over time.

It is an insulating material that will pay dividends in energy savings for the life of the walk-in cooler or freezer.

 

Urethane / Polyurethane: This material is formed from the reaction of two chemicals and is usually foamed through

the use of a lighter than air blowing agent such as Pentane or R134A.

Care must be taken by the manufacturer in the panel fill process with urethane / polyurethane insulated panels to avoid

air pockets in the panel as the mixture is foamed in place.

Air pockets cannot occur with expanded polystyrene or extruded polystyrene insulation.

 

Urethane achieves its high initial R-Value because of the lighter than air blowing agent that is trapped in the millions of tiny cells

that compose the material as the foam sets or "dries".

While its initial R-Value is fairly high, its R-Value is not as stable as polystyrene. Meaning that it can lose much of its

high initial R-Value due to outgassing of the cells that compose the material.

Its drawback is that because the gas in the cells is lighter than air, it is under constant pressure from the surrounding 

atmosphere to escape the cells, much as a balloon filled with Helium would.

As the lighter than air gas escapes it is replaced by air and moisture, the enemy of any insulation. As a result,

the high initial R-Value of the urethane insulation drops, thereby substantially reducing its R-value over time.

This process, and its effect on urethanes R-Value is know as "Thermal Drift". This effect is reduced because of the

metal skin but still occurs.

 

On the other hand, extreme R-Value degradation in polyurethane / urethane which was seen at one time in "unskinned"

applications subject to exposure to direct sunlight, such as sheets of raw urethane without a vapor / radiant barrier.

This problem has been resolved through the use of vapor / radiant barriers, as now used in the roofing industry, or

metal skins as is used with walk-in cooler panels.

It has a relatively low resistance to moisture penetration.

 

When urethane is manufactured, the cell gas is mostly  blowing agent, (now Pentane or R-134A), which have a low thermal

conductivity.

Over time, air and moisture will diffuse into the cells, diluting the blowing agent and degrading the thermal

value of urethane. Polystyrene on the other hand is not affected by outgassing.

Beginning in 2003 urethane manufacturers have adopted a LTTR method (Long-term Thermal Resistance).

Based upon a method for cutting very thin layers of foam, this method accelerates the air-diffusion and helps to predict

the final R-value.

 

As a result of this potentially dramatic lowering effect of outgassing on urethanes R-Value, most companies utilizing

urethane insulation in their panels will only refer to urethanes high initial R-Value, while not mentioning the much

lower "Aged", or "Long Term" R-Value of urethane.

In general the LTTR values now offered by the industry for urethane insulation are:

urethane thickness     initial r-value       long term r-value    percentage of decrease in r-value

1"                             8.57                    6.00                         -30%

1.5"                         12.86                    9.00                         -30%

2"                            17.14                   12.10                        -29%

2.5"                         21.43                   15.30                        -29%

3"                            25.71                   18.50                        -29%

3.5"                         30.00                  21.70                        -28%

4"                            34.00                  25.00                        -26%

In short, the Long Term R-Value for "Foamed in Place" urethane insulation can be as low as 6.25 per inch.

 

TO VERIFY THE R-VALUE OF "FOAMED IN PLACE"

URETHANE INSULATION FROM AN INDEPENDENT SOURCE.

LINK BELOW TO THE STATE OF COLORADO's ENERGY

CONSERVATION WEBSITE

(Look in the R-Value Table for Insulating Materials next to "Polyurethane (foamed-in-place)")

http://coloradoenergy.org/procorner/stuff/r-values.htm

 

 

Extruded Polystyrene: As with Expanded Polystyrene, this material also starts with solid beads. 

The beads are fed into an extruder where they are melted and additives mixed in.

A blowing agent is then injected into  the mixture to make it foamable.

This mixture is then extruded into flat sheets for use as insulation.

It has a slightly higher R-Value per inch than Expanded Polystyrene, and like Expanded Polystyrene, also

has good resistance to moisture penetration.

 

 

REFRIGERATION SYSTEM BASICS:

 

There are three primary components of a refrigeration system.

 

1. The evaporator coil: This is the part of the system that hangs from the ceiling inside of the walk in cooler or

walkin freezer, and is responsible for actually removing heat from inside of the walk in freezer or walk in cooler, in

other words, for blowing the cold air into the cooler or freezer vault.

 

If you have ever held an aerosol can in your hand and rapidly discharged it, you will have noticed that the can became

very cold.

The reason that the can felt cold was that the rapidly evaporating liquid propellant in the aerosol can was removing

heat from your hand as the liquid refrigerant in the can evaporated from a liquid state into a gaseous state, thereby 

making it feel cold.

The same evaporative cooling effect can be experienced as Alcohol evaporates from your skin. As the Alcohol evaporates

from your skin it removes heat, making your skin cold.

 

This is exactly what happens in an Evaporator Coil. The liquid refrigerant from the compressor flows from the

compressor through a flow metering device called an expansion valve into the Evaporator Coil, where it then rapidly

expands, or "evaporates".

This occurs in a series of finned metal coils that a fan or fans are blowing over. What is actually occurring is that large

amounts of heat are being removed from the air inside the cooler or freezer as the air, forced by the fans, flows over

the Evaporator Coil fins.

What we feel is the cold air that is produced as it blows into the cooler or freezer.

The refrigerant, now a gas, flows back to the Compressor.

 

 

2. The compressor: This is the Heart of the refrigeration system. Its primary purpose is to compress the refrigerant

coming from the Evaporator Coil as a gas, back into a liquid so that heat can be removed, and the refrigeration cycle

can continue.

(The two most popular types of compressors in use today are either Hermetic or Scroll. These will be discussed later.)

As the compressor recompresses the gas refrigerant coming from the Evaporator Coil, large amounts of heat are

released.

This heated gas refrigerant now goes to the Condenser to be dissipated.

 

 

3. The condenser: This is similar in function to a cars radiator. It is a series of large finned metal coils that looks

much like a cars radiator. The very hot gas refrigerant comes from the compressor into the Condenser coils as a

powerful fan or fans blows large amounts of air over the Condenser coils. The heat produced as a result of the

refrigerants compression by the compressor is dissipated as a result of the removal of heat, and the pressure in

the system.

The gas now becomes a liquid again, allowing the refrigeration cycle described above to continue.

 

 

TYPES OF REFRIGERATION SYSTEMS:

 

There are two major types of refrigeration systems. One is referred to as either a split, or remote system.

Either term describes the same system. In this approach, the evaporator coil is one separate unit, and the condenser

and compressor are combined as another separate unit.

The split / remote system is usually required for beverage display coolers and larger walk-in coolers and walk-in freezers

because of the size limitations of self contained refrigeration systems.

 

Split / Remote Refrigeration Systems: This type of system includes both indoor and outdoor remote systems.

The types we will discuss are field piped and charged. (There is another type of split system which will not be discussed

here, which involves lines which are pre-charged with refrigerant. These systems are seldom used because they still

require a Licensed refrigeration technician for installation, are more expensive, and do not provide the flexibility of a field

piped and charged system.)

This type of system is usually needed for beverage display coolers and walk in coolers larger than 8' x14', and walk in

freezers larger than 8' x 10' due to cooling capacity limitations on this type of system.

 

Indoor Remote: This type of system is the most inexpensive, but seldom make sense for the user. As a result of its

low price, this type of system is highly used by sellers of walk-in coolers and walk in freezers as the low price bait to entice

the customer to call.

In this type of system the condenser / compressor comes as one unit, but can only be installed indoors in an area not

subject to low temperature conditions.

In this, and all remote / split systems, the evaporator coil and condenser / compressor are separate units requiring

the expense of installation.

In this type of system the user still incurs the expense of installation of a remote system. Which will require a Licensed

refrigeration technician to run copper tubing between the evaporator coil and condenser / compressor, an electrician

to run control wiring between the condenser / compressor unit and evaporator coil, run drain lines from the evaporator

coil to drain away the water from the ice melted off the evaporator coil during the defrost cycle, and charge the

refrigeration system with refrigerant.

The only time this system would make sense, is if the condenser / compressor unit were to be located far away from the

walk in cooler or walk in freezer, such as in a basement. Since this scenario is seldom the case, and the user usually

intends to mount the compressor on top of the walk in cooler or walk in freezer, the better choice would be a self

contained refrigeration system.

 

Outdoor Remote:

 

Same as indoor remote, with the exceptions that the compressor / condenser unit is designed to be installed outdoors in

either rain or snow, and has special controls so that it can properly function in low temperature conditions.

 

 

SELF CONTAINED REFRIGERATION SYSTEMS: In this type of system all of the components of a refrigeration

system are contained in one package and is pre-charged with refrigerant. Because of refrigeration size limitations, this

type of system is usually only available for relatively small walk in coolers and walk in freezers.

This type of system includes Penthouse units which are mounted on top of the walk in cooler or freezer, and wall mount

units which are mounted on the wall of the cooler or freezer. (A Seldom used system also available is like the wall mount,

but is rolled up to the opening on the wall of the cooler or freezer.)

 

Penthouse Refrigeration (Also Referred to as "Drop In"): This is the most popular type of

self contained refrigeration system.

The Penthouse unit mounts on top of the walk in cooler or walk in freezer into a pre cut opening on one of the ceiling

panels.

It mounts flush with the inside of the ceiling so that none of it hangs down into the cooler or freezer, maximizing usable

interior space.

The unit is pre-charge with refrigerant, should usually come with an attached power cord, has a factory set defrost timer,

and is therefore "plug and play". Requiring no plumbing, control wiring, or refrigeration technician for installation.

Thereby greatly reducing total cost for your walk -in cooler or freezer.

 

Wall Mount Units: same as Penthouse units above, except that they mount on one of the walls as opposed to the

ceiling.

 

Roll Up Units: Basically a wall mount unit mounted on casters so as to make it easier to mount in the

opening on the side of the cooler. These are systems are seldom used today.

 

 

 

TYPES OF COMPRESSORS:

 

There are two main types of compressor's in use today.

 

A. HERMETIC:

The most common is the hermetic compressor, this type of compressor compresses the refrigerant gas back to liquid by

use of pistons and cylinders, and as the name indicates, is hermetically sealed, this minimizes maintenance,

but does not allow the interior of the compressor to be repaired in case of break down. If there is an internal problem

the compressor cannot be repaired and therefore must be replaced. If under warranty coverage the unit is simply

replaced with another compressor. If not under warranty, a new compressor must be purchased.

 

B. SCROLL

A newer, more advanced and much more energy efficient type of compressor is the "Scroll Type".

These compressors use two scroll shaped elements to compress the gas in one smooth continuous motion making

them quieter and longer lasting than an old fashioned piston driven hermetic compressor, and due to the higher

compression rate and reduced leakage, and often more energy efficient as well.

For more information on the advantages of "Scroll Type" compressors from an independent source,

please visit: http://www.wisconsinpublicservice.com/farm/scroll.asp 

 

 

TYPES OF EVAPORATOR COILS

 

 

There are two main types of defrost systems for evaporator coils.

 

A. AIR DEFROST

This is by far the most common evaporator coil systems in walk in coolers where a temperature of 35 degrees fahrenheit

or higher is desired.

As the name implies, the ice that forms on the evaporator coils cooling fins during operation is melted off the coils during

defrost cycle by air from the evaporator coil fans blowing the air inside of the cooler over the coil fins and

gradually defrosting them. This system is used on most walkin cooler refrigeration systems for restaurant coolers,

beverage coolers and other medium temperature, (35 to 38F), applications.

Because defrosting is dependent on the air temperature inside of the cooler, for proper defrost to occur, the temperature

setting for the cooler should be set no lower than 35F, setting the thermostat lower than this might not allow the ice that

has built up on the evaporator coils to completely melt, eventually leading to ice build up on the coils.

Since ice is a thermal insulator, this ice build up prevents the system from removing the heat inside of the cooler as it should.

 

 

B. ELECTRIC DEFROST

For walk in beer coolers or walk in keg coolers, where very low temperatures are desirable, and in freezers, the more

expensive electric defrost coils will be needed. As the name implies, during the defrost cycle, a heating element is

employed to rapidly defrost the evaporator coils and the system can quickly complete the defrost cycle and resume operation.

This system, though more expensive, is a must for a walkin beer cooler to be able to maintain the temperature at or below

freezing, since in an air defrost system, the coils couldn't defrost by air, if the air temperature is below freezing.

If you want "the coldest beer in town" you will have to use electric defrost coils in the walk in refrigeration system for your walk

in refrigerator, walkin beer cooler or walkin keg cooler.

(If using an electric defrost system in a cooler with glass doors, you will have to use heated glass to avoid condensation on th glass)

 

Evaporator coil fan motors:

There are two main types of evaporator coil fan motors in use today.

Permanent Split Capacitor (P.S.C.) and Shaded Pole.

 

Permanent Split Capacitor (P.S.C.) fan motors are over 50% more energy efficient than "shaded pole" motors.

For comparison: The typical shaded pole motor draws 2.1 amps per fan motor. The typical P.S.C. motor only 1 amp.

 

Keep in mind: A typical evaporator coil has three or more fan motors. And many walk in coolers and freezers use

more than one evaporator coil, and that in an air defrost system as used in most walk in coolers, the evaporator coil

fan motors run 24 hours a day.

The only reasons that P.S.C. motors are not as commonly used as "shaded pole" fan motors in walk in coolers and freezers.

is:

1. They are more expensive than the older and less efficient "shaded pole" type fan motors.

2. There is not widespread consumer awarenes of even the option of this type of fan motor. 

For more on energy saving ideas and the importance of P.S.C. motors in energy saving, please visit the link below:

http://www.wisconsingrocers.com/images/Magazine/Energy%20savings%20spring%2003.pdf#search='permanent%20split%20capacitor%20energy%20saving'

(copyright pending)

 

SPECIAL NOTICE FOR OUR CALIFORNIA CUSTOMERS.

NEW APPLIANCE ENERGY REGULATIONS PASSES IN 2006 ARE

NOW IN EFFECT AND STILL REQUIRED IN 2007.

 

TO MEET CODE, WALKIN COOLERS WILL HAVE TO HAVE

PANELS OF 6 INCHES OF POLYSTYRENE OR 4 INCHES OF

URETHANE INSULATION.

 

WALKIN FREEZERS WILL HAVE TO HAVE PANELS WITH A MINIMUM

OF 8 INCHES OF POLYSTYRENE OR 5 INCHES OF URETHANE INSULATION.

IF YOU HAVE BEEN QUOTED A WALK IN COOLER OR WALK IN

FREEZERWITH LESS THAN THIS, IT WILL NOT MEET CODE!

YOU CAN DOWNLOAD THE NEW LAW FROM THE LINK BELOW.

http://www.energy.ca.gov/appliances/2006regulations/index.html 

(Look at pages 108 and 109 for Walk-In Refrigerators and Walk-In Freezers)

 

 

WE OFFER BOTH WALK IN COOLERS AND WALK IN FREEZERS

THAT MEET CALIFORNIA ENERGY COMMISION

REQUIREMENTS!