Plasseringen av kjølerøret er viktig.

Because -en is the definite singular ending here.

The base noun is plassering.

• en plassering = an/a placement
• plasseringen = the placement

Norwegian usually marks definiteness by adding an ending to the noun, instead of using a separate word like English the.

Here av means of.

So the structure is:

• plasseringen = the placement
• av kjølerøret = of the cooling pipe

This is a very normal way to connect two nouns in Norwegian, especially when the first noun is an abstract one like plassering, bruk, farge, størrelse, and so on.

Because kjølerøret is the definite singular form:

• et kjølerør = a cooling pipe / a cooling tube
• kjølerøret = the cooling pipe / the cooling tube

The sentence is talking about a specific pipe, not just any pipe in general.

If the meaning were more general, you might see something like:

• Plassering av kjølerør er viktig = Placement of cooling pipes is important / The placement of cooling pipes is important

Yes, it is one compound word, which is very typical in Norwegian.

It is made from:

• kjøle = cool / cooling
• rør = pipe / tube

Together: kjølerør = cooling pipe / cooling tube

When a compound noun becomes definite, the definite ending goes on the whole word:

• et kjølerør
• kjølerøret

Kjølerør is a neuter noun.

You can see that from the forms:

• et kjølerør
• kjølerøret

The definite ending -et is a common sign of a neuter noun in Bokmål.

In this sentence, plassering is being used as a common-gender noun:

• en plassering
• plasseringen

Er is the present tense of å være = to be.

This sentence states a general fact, so Norwegian uses the present tense:

• Plasseringen av kjølerøret er viktig.

That works the same way as English is important.

Here viktig is a predicate adjective, because it comes after er.

In Norwegian, predicate adjectives often agree with gender and number, but with viktig you do not see a difference between common gender and neuter singular:

• en viktig del
• et viktig rør

Both are viktig.

You do see a different form in the plural:

• Plasseringene er viktige. = The placements are important.

So in this sentence, viktig is exactly the form you would expect.

It follows the normal Norwegian main-clause pattern:

Subject + verb + complement

So:

• Plasseringen av kjølerøret = subject
• er = verb
• viktig = complement

Norwegian is a V2 language, which means the finite verb usually comes in the second position in main clauses. Since the subject comes first here, the verb follows it immediately.

For example:

• Plasseringen av kjølerøret er viktig.
• I dette systemet er plasseringen av kjølerøret viktig.

In the second sentence, I dette systemet comes first, so er still stays in second position.

Yes. That is also correct.

It uses the -s genitive:

• kjølerørets plassering = the cooling pipe's placement / the placement of the cooling pipe

So these are both possible:

• Plasseringen av kjølerøret er viktig
• Kjølerørets plassering er viktig

The version with av often feels a bit more natural when the phrase is longer or less tightly connected. The -s version can sound a little more compact or formal.

Yes.

The original sentence points to a specific placement and a specific pipe:

• Plasseringen av kjølerøret er viktig.

A more general version could be:

• Plassering av kjølerør er viktig.

That sounds more like the placement of cooling pipes is important or placement of cooling pipes is important in a general sense.

So definite forms often signal something specific, while bare or indefinite forms are often more general.

The tricky part is usually kjø.

A rough guide:

• kj before ø is a soft sound that many learners approximate as a very soft sh at first
• ø is a rounded vowel that English does not really have

A rough syllable breakdown is:

• kjø-le-rø-ret

The main stress is on the first syllable:

• KJØ-le-rø-ret

A practical learner tip: do not pronounce the kj like the English k in key. It is much softer.