Der Verdampfer ist kalt.

Der is the definite article meaning the. In this sentence, Verdampfer is a masculine noun, so in the nominative case it takes der.

So:

• der Verdampfer = the evaporator

Because Verdampfer is the subject of the sentence, der is the correct form here.

In German, every noun has a grammatical gender: masculine, feminine, or neuter. Verdampfer is a masculine noun, so its basic dictionary form is:

• der Verdampfer

A useful pattern is that many nouns ending in -er are masculine, especially nouns for devices, tools, or people, though this is not a perfect rule.

Ist is the he/she/it form of the verb sein, which means to be.

The full present-tense forms of sein are:

• ich bin = I am
• du bist = you are
• er/sie/es ist = he/she/it is
• wir sind = we are
• ihr seid = you are
• sie/Sie sind = they are / you are

Since der Verdampfer is a singular noun treated like he/it grammatically, German uses ist.

Here kalt is a predicate adjective, meaning it comes after the verb sein and describes the subject.

In German, predicate adjectives do not take adjective endings.

So:

• Der Verdampfer ist kalt. = The evaporator is cold.

Compare that with an adjective before a noun, where endings do appear:

• der kalte Verdampfer = the cold evaporator

So:

• after sein: kalt
• before a noun: kalte

Yes, in this sentence it is very similar to English:

• Der Verdampfer = the subject
• ist = the verb
• kalt = the description

So the structure is:

• Subject + verb + adjective

This makes Der Verdampfer ist kalt. a very straightforward sentence for English speakers.

In German, all nouns are capitalized, not just proper names.

So Verdampfer must begin with a capital letter because it is a noun.

Compare:

• der Verdampfer = the evaporator
• kalt = cold

Only the noun is capitalized here.

Yes, depending on context, Verdampfer can refer to an evaporator, vaporizer, or a part of a machine or cooling system. German technical vocabulary often depends heavily on context.

But grammatically, the sentence works the same way no matter which exact technical meaning is intended:

• Der Verdampfer ist kalt.

Yes. That would mean An evaporator is cold or One evaporator is cold, depending on context.

The difference is:

• Der Verdampfer ist kalt. = The evaporator is cold.
• Ein Verdampfer ist kalt. = An evaporator is cold.

So the article changes the meaning slightly, just as in English.

A rough English-friendly guide is:

• fair-DAMPF-er

A few notes:

• Ver- is often pronounced more like fer- than ver-
• dampf has a strong p/f cluster
• the er at the end is usually reduced, not fully pronounced like English air

A more careful approximation is:

• fehr-DAMP-fer

The stress is on dampf.

Es ist kalt means It is cold, usually talking about the weather, the general temperature, or an unspecified situation.

But in Der Verdampfer ist kalt, the speaker is talking about a specific thing: the evaporator.

So:

• Es ist kalt. = It is cold.
• Der Verdampfer ist kalt. = The evaporator is cold.

The second sentence is more specific.

It is in the nominative case because it is the subject of the sentence.

You can think of it this way: the thing that is something is usually the subject, so it takes the nominative.

• der Verdampfer = nominative masculine singular

That is why the article is der, not den or dem.

Not literally. The German sentence simply says The evaporator is cold.

In context, English might sometimes choose a slightly different phrasing such as The evaporator feels cold if someone is touching it, but the German itself does not contain a separate verb for feels here.

So the direct grammar is:

• ist = is
• kalt = cold

Yes. You would say:

• Der Verdampfer ist nicht kalt.

Nicht is the usual word for not when negating an adjective or a whole statement.

So:

• Der Verdampfer ist kalt. = The evaporator is cold.
• Der Verdampfer ist nicht kalt. = The evaporator is not cold.