If you { turned / would turn } down the volume of the TV, that would be great

Question

1. If you turned down the volume of the TV, that would be great.
2. If you would turn down the volume of the TV, that would be great.

Are both the above sentences grammatically correct? What difference is there in their meaning?

Answer 1

I would say that both examples are grammatical and I guess your concern has something to do with the use of would in if-clauses. If so keep in mind that in polite requests would is possible in if-clauses.

Regarding the meaning, your both examples convey the same idea, yet the second example is more polite.

Answer 2

The first one stick to the second conditional form, the second doesn't.

If you want to have the second one with the second conditional form, you can use could:

If you could turn down the volume of the TV, that would be great.
(I can't do it, so it's not great.)

This works since it sticks with the if + past simple in the main clause as could being the past simple of can.

---

Now if you want that the behaviour of something or something to be different, you can use if only + would + base form:

If only you would turn down the volume of the TV.

Answer 3

Both are correct, and just a little awkward. Consider the following versions:

If you could turn down the volume, that would be great.

...

"Mind turning down the volume a little?"
"Like, right now?"
"That would be great, thanks."

The TV part can be skipped. Think about it.