Combustion air supply / chimney stove - thermal air draft or base plate

I feel misunderstood. We have a heat pump with underfloor heating and no warm air heating. We have the controlled residential ventilation for basic ventilation and because we want the comfort. Dust should therefore be a smaller issue.

Nevertheless, we would like to have a small wood stove. The controlled residential ventilation should be able to refute the argument of local overheating that was previously presented.

My concern here is about the supply air. Not whether radiant heat would be more pleasant.

In the end, I have already read here that there are some arguments against draft air over the floor slab and the disadvantages of draft air over the chimney seem negligible in comparison.

I thank everyone who has contributed purposeful answers here.

Sorry my fault! You already wrote further above that you want the fireplace not for heating, but for the look or coziness. Then everything fits.

I just wanted to point out that a fireplace is rather unsuitable for heating. It may well be that people are reading here or see the thread later who want to use a wood stove for heating. That’s why my comment.

Our chimney builder recommended a LAS chimney flue for the new building. So, as already mentioned, a chimney with a "double pipe". Reasons:

With air coming through the floor slab, a kind of draft constantly occurs through the air exchange. This is attempted to be prevented by a pressure flap, which is installed in the wall where the supply air duct outlet is.

The air through the floor slab is much colder in winter, and condensation can form below the combustion chamber, which can negatively affect the lifespan of the chimney.
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I would be interested in a brief explanation of how this is supposed to work.

Otherwise, from my chimney experience so far, I can only report that the chimney makes the house really warm. That's what it's supposed to do; for me, that's part of the feeling. If it gets too intense, the patio doors are just briefly thrown open.

The only thing that bothered me was the very dry air due to convection. We don't have controlled residential ventilation.

All right. Thanks for the clear

Hello everyone,

the topic is somewhat older, but this is exactly the point we are at right now.

We want to build a single-family house with Kfw55 according to the reference value. We will install a ventilation system with heat recovery (controlled residential ventilation) and are considering or would like to have a masonry fireplace (fireplace kit) installed in the open kitchen/dining/living area (approx. 53 sqm).

Our architect pointed out to us that this fireplace should/must be certified as room-air-independent to avoid any negative surprises during the later blower door test and possibly exceeding the limit values if the fireplace is not airtight.

We recently visited a stove builder and expressed our wish for a masonry, room-air-independent fireplace. He then recommended a "LAS fireplace" and said he regularly installs these in new builds and KFW houses.

Does anyone happen to have experience with the interaction of a "LAS fireplace," blower door test, and KfW? Does it work that way, or is there a risk of not passing the blower door test and therefore possibly not receiving KfW funding?

Thank you very much.

P.S. A pressure monitor is included.

The BDT does not necessarily have anything to do with the chimney... It could also be carried out if the chimney is not yet installed. Then the chimney connection is sealed. Otherwise, everything is described here that should be considered in connection with [Kontrollierte-Wohnraumlüftung] and the chimney... The risk of not passing the BDT is low. In the worst case, troubleshooting/-repair will have to be carried out.