Which chimney variant?

We have so far spoken with 3 chimney builders and all favor different options for the fresh air supply. We will decide on a room-air-independent fireplace and therefore need a fresh air supply from outside. We were recommended the following options:

1. Pipe through the floor slab with a mushroom vent in the garden
2. Chimney with two ducts side by side, 1x exhaust gas, 1x fresh air (e.g. Schiedel xpert)
3. Chimney with concentric air intake guidance (e.g. Erutec FLAS)

Option 1 can be fairly inexpensive, but we do not want a pipe or mushroom vent standing outside.

We like option 2.

Option 3 is supposed to preheat the fresh air, which then burns better. On the other hand, I can imagine that the warming fresh air might be reluctant to fall downward and thus its functionality may be rather poor depending on the weather.

Do you have any good advice on this?

Choose option 1. The air intake/pipe can be hidden outside, for example nicely behind a bush or similar. Then it is not visible and you have more money left for other gadgets.

Choose option 1. The air intake/pipe can be nicely hidden outside, for example behind a bush or similar.

Why _that_ then? The OP needs a chimney draft anyway, so the fresh air supply can also be realized through it

Rhenish greetings

I originally wanted to do without external air supply, but had a chimney installed comparable to your variant 3 (TONATec plus). I think the additional cost was not significantly higher. After I realized how airtight such a house can be (the stove could only operate with open windows, which somehow makes the whole thing absurd), I was able to easily connect the stove (which I had of course purchased so that it could be easily converted) to the chimney with fresh air supply. You can hardly see anything except the short second nozzle from the stove to the chimney. It works great and looks neat. Variant 1 would not have been an option for me at all.

Why _this_ then? The OP needs a chimney flue anyway, so the fresh air supply can also be realized through this

Rhenish greetings

Because the additional pipe is installed for free with a little negotiation skill (for us it was €50 that this variant cost). Then the cheapest chimney variant is sufficient - that saves a lot of money.

Choose option 1. Air intake/pipe can be nicely hidden outside, e.g. behind a bush or similar.

We want to keep garden and terrace design flexible and therefore very reluctantly allow the fireplace to dictate where a bush should be planted.

Can anyone understand the argument against this option?