Dometic RM760 Manual de usuario descargar pdf

How a Cooling Unit Works

ATCO

GALVANIZED

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800.227.3180

RV refrigeration manufacturers have known the value of zinc protection for decades. In fact, all Dometic cores with tubes ex-

tending into the freezer compartment have a galvanized coating on these tubes to prevent rusting in a visible area. At one time

Dometic also galvanized the tubes in the foam block. New models marketed within the last 20 years do not have this protection,

giving ATCO cooling units a dramatically longer life than new Dometic or Norcold cores. We are the largest cooling unit manu-

facturer, new or remanufactured, to do this full-tube-set galvanizing. We believe with the new generator design and galvanized

tubes, an ATCO replacement cooling unit will last longer than a new refrigerator.

Not Your Kitchen Refrigerator

An RV refrigerator works very differently than a household refrigerator. To get the most out of an RV refrigerator, it’s helpful to

know how the cooling unit keeps things cool. The refrigerator has hundreds of parts, and the cooling unit is the single most

costly part to buy and the most time-consuming one to change. So you should be sure the cooling unit is the problem before

replacing it. (See the Support section of our Web site for helpful information.)

Cooling Using Natural Forces

An RV refrigerator cooling unit uses ammonia as the refrigerant and has NO moving parts. No compressor, no fan, no pump. It

does its job by using basic forces of nature, a minimum of added energy, and the principles that evaporation causes cooling and

that water wants to absorb gaseous ammonia.

A Closed-loop System

The unit itself is 50 to 60 feet of steel tubing in a closed-loop system. It has a few cups of ammonium hydroxide (ammonia and wa-

ter) refrigerant that is boiled in the boiler/generator to create a vapor that rises to the top of the unit. At the top, the condenser ﬁ ns

cool the vapor into a liquid that is rich in ammonia. This liquid, by gravity, ﬂ ows down to a section of tubes that allow it to evapo-

rate, causing cooling. This ﬁ rst set of cooling tubes is in the freezer section and is sometimes referred to as the primary evaporator.

A section of the tube set is covered with a rigid polyurethane foam block. This keeps the tubes insulated from the warm

ambient air so they don’t pick up heat from the outside. A tube comes out of the foam block in the refrigerator area, where it

usually has an aluminum ﬁ n assembly screwed onto it to collect heat from the refrigerator box. This is called the secondary

evaporator.

The Top-down Evaporation Cycle

In the top end of the unit (from the primary to the secondary evaporator) the rich ammonia ﬂ uid has been evaporating to cause

cooling. After ﬂ owing through the evaporator sections the ﬂ uid is spent of its evaporating ammonia, and any remaining ﬂ uid

is joined with the weak ﬂ uid from the boiler and ﬂ ows into the oblong spiral of tubes above the tank. These are called absorber

tubes, and their purpose is to allow the ﬂ uid to pick up gaseous ammonia that comes up from the tank that acts as a reservoir of

ammonium hydroxide. The ﬂ uid absorbs the ammonia as it travels to the tank. The tank has a tube coming out the bottom that

feeds the boiler to start the process all over again.

In Summary, the Sequence of Processes is:

Liquid ammonium hydroxide is boiled;

The ammonia vapor is condensed into liquid;

The rich ammonia liquid evaporates;

The weak ammonia liquid absorbs gaseous ammonia and is returned to the reservoir tank.

ATCO America RV refrigerator cooling unit instructions —provided as a service to our dealers

based on our years of experience supporting RV service technicians.

www.atcoamerica.com

How it Works

Page 1

Contents of this PDF

How a Cooling Unit Works pages 1–2

RV Refrigerator Cooling Unit Removal and Installation Instructions pages 3–6

1 2 3 4 5 6

ATCO 1

Indice de contenidos

Pagina 1 - ATCO

How a Cooling Unit WorksATCOGALVANIZED800.227.3180RV refrigeration manufacturers have known the value of zinc protec

Pagina 2

Rust: the EnemyAlthough many owners assume a cooling unit failure is caused by “blockage,” about 25 years ago manufacturers changed the boiler design

Pagina 3

RV Refrigerator Cooling Unit Removal and Installation InstructionsPlease carefully review these instructions, along with the Troubleshooting document

Pagina 4

12. Refrigerator ﬁ ns are attached in different ways, varying by make and model. a. Norcold refrigerator ﬁ ns will remain in place in the box during

Pagina 5

ATCOGALVANIZED800.227.3180800.227.3180RV Refrigerator Cooling Unit Removal and Installation InstructionsATCO America

Pagina 6

ATCOGALVANIZED800.227.3180RV Refrigerator Cooling Unit Removal and Installation InstructionsATCO America RV refriger