Термоголовка закрыта.

In Russian, the verb to be is usually omitted in the present tense.

So:

• Термоголовка закрыта = The thermostatic valve head is closed
• literally: Thermostatic-head closed

Russian normally does not say Термоголовка есть закрыта in this kind of sentence.

But in the past or future, forms of to be do appear:

• Термоголовка была закрыта = The thermostatic valve head was closed
• Термоголовка будет закрыта = The thermostatic valve head will be closed

Because закрыта agrees with термоголовка, which is:

• feminine
• singular

The short-form adjective/participle changes depending on gender and number:

• закрыт — masculine
• закрыта — feminine
• закрыто — neuter
• закрыты — plural

Since термоголовка is feminine, Russian uses закрыта.

Here закрыта is the short form of закрытый (closed).

In sentences like this, Russian often uses the short form to describe a current state:

• Дверь закрыта = The door is closed
• Окно открыто = The window is open
• Термоголовка закрыта = The thermostatic valve head is closed

The short form is very common in predicate position, especially after the subject.

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

The basic dictionary form is термоголовка, and that is also the nominative singular form.

So in this sentence:

• термоголовка = the thing being described
• закрыта = tells us its state

In this sentence, it mainly describes a state: the thermostatic valve head is in the closed position/state.

Russian short forms like закрыт / закрыта / закрыто / закрыты often focus on the resulting condition rather than the action itself.

If you wanted to emphasize the action by someone, Russian would often use a different structure, for example:

• Термоголовку закрыли = They closed the thermostatic valve head
• Термоголовка была закрыта = The thermostatic valve head was closed

So Термоголовка закрыта most naturally means it is closed.

It can often mean both, depending on context.

With physical objects, закрыт / закрыта usually means closed. But with valves, taps, vents, and similar devices, English may naturally translate it as:

• closed
• shut
• shut off

So for a heating or plumbing context, Термоголовка закрыта could idiomatically mean that the valve head is set so that flow is shut off.

Yes, Russian word order is flexible.

The neutral, most straightforward version is:

• Термоголовка закрыта.

But you could also say:

• Закрыта термоголовка.

That version sounds more marked and may put extra focus on closed or fit a particular context. For basic learning, the original order is the best one to use.

A helpful approximate pronunciation is:

• tyer-ma-ga-LOV-ka zak-RY-ta

Stress:

• термоголо́вка
• закрыта́

A few sound notes:

• Russian е after т here sounds roughly like tye
• unstressed о is reduced, so it does not sound like a strong English o
• ы in закрыта is a distinct Russian vowel, not exactly English i or u

Russian has no articles like a or the.

So Термоголовка закрыта could correspond to:

• The thermostatic valve head is closed
• A thermostatic valve head is closed

Which one is intended depends on context. In most real situations, the listener already knows which object is being discussed, so English often uses the.

Not in the same way.

• Термоголовка закрыта is the normal way to say The thermostatic valve head is closed
• закрытая is the full form adjective, and it usually needs to be part of a noun phrase, such as:
  • закрытая термоголовка = a closed thermostatic valve head

So:

• Это закрытая термоголовка = This is a closed thermostatic valve head
• Термоголовка закрыта = The thermostatic valve head is closed

That is why the short form закрыта is used in your sentence.