Learn Hardcore Turkish: Şofben açılır açılmaz su hemen ısınacak. - As soon as the water heater turns on, the water will heat up immediately.

It means as soon as it is turned on/opened. It’s a set pattern built from the same verb in the aorist (simple present) once in the affirmative and once in the negative:

aç- (to open/turn on) + -ıl (passive/intransitive) → açıl- (to be opened / to get turned on)
açılır = aorist, 3rd person singular, affirmative
açılmaz = aorist, 3rd person singular, negative Putting them together (açılır açılmaz) gives the idiomatic meaning “the moment it is opened; no sooner than it is opened.”

Common parallels: gelir gelmez (as soon as he comes), çıkar çıkmaz (as soon as he goes out).

Why is the passive voice used (açılır) instead of an active form?

Because the doer is unspecified/irrelevant. In English we’d say “as soon as the water heater is turned on,” not “as soon as someone turns on the water heater.” Turkish mirrors that with the passive açılır. If you want to mention the agent or use an active frame, you switch to active forms (see next question).

Can I say the active version Şofbeni açar açmaz su hemen ısınacak?

Yes. That means “As soon as you/he/she turns on the water heater, the water will heat up.” In the active pattern:

You use açar açmaz (active aorist + negative aorist).
Şofben becomes a direct object, so if it’s specific/definite (“the water heater”), you mark it with accusative -i: şofbeni. Both passive and active are natural; choose based on whether you want to mention an agent.

Is hemen redundant when the sentence already has açılır açılmaz?

It’s not required, but it adds emphasis. Açılır açılmaz already implies immediacy (“as soon as”), and hemen (“immediately, right away”) reinforces that quickness. You can omit hemen without changing the core meaning.

Why is the future tense (ısınacak) used? Could I say ısınır instead?

ısınacak = a specific future event (“will heat up then”).
ısınır (aorist) = habitual/general truth (“it heats up [whenever that happens]”). So:
Şofben açılır açılmaz su hemen ısınacak = a particular future instance.
Şofben açılır açılmaz su hemen ısınır = a general statement about how it works.

Why is it ısın-acak (with -acak) and not ısın-ecek?

Vowel harmony. The last vowel in the stem ısın- is back and unrounded (ı), so the back variant -acak is used (not the front -ecek).

How do I spell and pronounce ısınacak correctly?

Spelling: ısınacak (both i’s are the dotless ı). Writing isinacak is wrong.
Approximate pronunciation: like “uh-suh-NA-jak.” The Turkish ı is a back, unrounded vowel (not like English i).

What exactly is a şofben?

A şofben is an instantaneous water heater (often gas or electric) that heats water on demand. Related terms:

termosifon: storage-type electric water heater (tank).
kombi: combi boiler (heats radiators and provides hot water). Note: The standard spelling is şofben (you may see şohben colloquially, but şofben is the norm).

Why is there no word for “the” before su?

Turkish has no articles like “the” or “a.” Definiteness is shown by context, word order, and case marking. Here su (water) is a mass noun and the subject; context supplies whether it’s “the water” or just “water.” No article is needed.

Is the word order fixed? Can I move su to the front?

Turkish is flexible, but the default is subordinate clause first, then main clause, with the main verb at the end. Variants:

Şofben açılır açılmaz, su hemen ısınacak. (original; neutral)
Su, şofben açılır açılmaz hemen ısınacak. (focusing “water”)
Şofbeni açar açmaz su hemen ısınacak. (active frame) Keep the finite verb (ısınacak) at the end for naturalness.

Do I need a comma after açılır açılmaz?

Not required, but acceptable for readability in longer sentences: Şofben açılır açılmaz, su hemen ısınacak. In short clauses, many writers omit it.

Are there other common ways to say “as soon as” in Turkish?

Yes:

The same-verb aorist pattern: gelir gelmez / açar açmaz (active), açılır açılmaz (passive).
-ınca/-ince: Şofben açılınca su hemen ısınacak. (when/once it’s turned on; a bit less emphatic than “no sooner than”)
-diği anda: Şofbeni açtığın anda… (the moment you turn it on)
Colloquial -dığı gibi: Eve geldiğim gibi yattım. (As soon as I got home, I lay down.)

Do the subjects of the two parts have to match in the V-ir V-mez pattern?

They don’t have to, as your sentence shows:

Subordinate clause subject: şofben (it is turned on).
Main clause subject: su (it will heat up). If you use the active pattern (açar açmaz), make sure any needed subjects/objects are clear and properly marked.

Could I use ısıtmak instead of ısınmak here?

ısınmak = to get warm (intransitive; the water warms itself up).
ısıtmak = to heat (transitive; something heats something). Your sentence focuses on the water’s state change, so su ısınacak is perfect. A transitive alternative:
Şofben açılır açılmaz şofben suyu hemen ısıtacak. (focus on the device doing the heating) Or passive transitive:
Şofben açılır açılmaz su hemen ısıtılacak.

Is hemen hemen the same as hemen?

No. hemen = immediately; hemen hemen = almost/nearly. Don’t confuse them.

Is açılınca fully interchangeable with açılır açılmaz?

Often, yes, but there’s a nuance:

açılır açılmaz = no sooner than the moment it’s opened (strong immediacy).
açılınca = when/once it’s opened (more neutral; can be more general/habitual). So Şofben açılınca su hemen ısınacak is fine, just slightly less emphatic than açılır açılmaz.