Reverse Thrust Issue in 62m2 Apartment: Ventilation Grilles, Pressure Diffusers & Window Solutions

I warmly welcome,
I moved to a 3-room flat + bathroom + wc. Area 62 m2. The apartment has separate ventilation ducts, 3rd floor, in a 3-story block. The kitchen has two ventilation grilles next to each other. One hood is connected to one. There is one grid in the toilet next to the kitchen. The bathroom has two grilles. In the kitchen and in the large room, the windows are wooden with cut out gaskets at the top, and probably even in some places sealing with gaskets (approx. 15 years). In the other two rooms, plastic windows tight. Some time ago I noticed the phenomenon of reverse thrust in the kitchen and toilet. I studied internet resources and installed 1 pressure diffuser for each room and kitchen. The situation has not improved. Only opening the window stabilized the situation. I decided to experiment with covering the grilles. With foil covering one grille in the bathroom (where the draft is correct) and in the toilet. The kitchen stopped blowing, but somehow it did not pull out too. I continued reading and an employed chimney sweep lengthened the chimneys from one grille in the kitchen (the one without the eaves) and from the toilet. In wc the situation stabilized and the sequence is. In the kitchen, however, the wind blew even a little less. I covered one box in the bathroom again. To check if the draft in the kitchen returned, I accidentally touched the ventilation duct right next to the grille. It's very cold. In addition, I felt cold near the engine in the roof of the hood. As I mentioned, the kitchen is adjacent to the toilet and the wall with ventilation chimneys is very cold, the temperature in the morning is 17 degrees in the toilet. Very unpleasant feeling. Humidity in the apartment at 35 -45% is also normal. But for the apartment to reach 20 degrees, all radiators must be turned on for a minimum of 3.5, and it cools down quickly. My guess is that through the diffusers, so I set them to trial and error to the optimal position, but still feel the cold air above my head. I have a question what to do with this hood, which cools my kitchen and toilet. Can also extend the ventilation chimney? Bills for heating for a month are about PLN 230, and the average temperature is less than 20.3 degrees. The massacre, and the frosts so far have been -5 degrees. In a month the family will grow and I need to ensure optimal conditions for the child. And it seems to me that the ideas are over. Yes, I can heat and tilt the window, but instead of pampers I will spend a lot of money on heating, and eventually the fungus will come out, or some bacteria on the ever-cold wall ? I am asking for some constructive suggestions. Thank you in advance.

If he was a chimney sweep, why did he not take measurements of the lift? At that time, you would know if there is too much of it and it should be suppressed or not enough, and you panic that your windows are blowing. Now we can take or measure ventilation.

4 grilles + hood, together around 280m3 / h is too much. The humidity level also confirms this. Two in the bathroom, probably one for the boiler. If there is no boiler, stop it. On others. Fit the adjustable grilles. On 3 sheets, you need to limit the flow to around 100m3 / h, i.e. 30m3 / h. The hood must be with a flow stop valve when turned off. The diffusers must have a total capacity of 100m3 / h, e.g. 4 windows of 20m3 / h.

p.obelix wrote:

If he was a chimney sweep, why did he not take measurements of the lift? At that time, you would know if there is too much of it and it should be suppressed or not enough, and you panic that your windows are blowing. Now we can take or measure ventilation.

He is such a chimney sweep ... He stated that he is similar in winter and clogs the foil with foil, I did not even want to enter into the discussion.

Added after 9 [minutes]:

Wlodek22 wrote:

4 grilles + hood, together around 280m3 / h is too much. The humidity level also confirms this. Two in the bathroom, probably one for the boiler. If there is no boiler, stop it. On others. Fit the adjustable grilles. On 3 sheets, you need to limit the flow to around 100m3 / h, i.e. 30m3 / h. The hood must be with a flow stop valve when turned off. The diffusers must have a total capacity of 100m3 / h, e.g. 4 windows of 20m3 / h.

The block from 2002 boilers was not planned. In the kitchen I put on an adjustable grille as in the picture. In the bathroom all the time one grille is covered. Mounted diffusers are Ventair II Trdn with an air flow of 25m3 / h. The hood is Faber Synthesis x 90, I was looking for specifications in the network and I think it should have a blocking valve, but I'm not sure. I screwed the diffusers to a minimum gap, because they cool the room very much. I wonder to completely blind the eaves grille from the inside, because I do not use too often only in cooking, but then I still have to open the window. Also, I think I would just open the window while cooking.

You must understand how gravitational ventilation works.
It will always be accompanied by the phenomenon of "cooling" the rooms. You have to come to terms with it and simply adjust it.
If you limit the inflow of air, on the other hand, already with two ventilation risers, vertical back draft with weaker draft may occur. So limit and align the flows on the sheets and do not limit the diffusers.

In your opinion, which grids should I restrict in the flow? Hood and toilet?

I blocked the eaves duct. In the toilet I covered half the grille. In the bathroom, as you said, I blocked one box. Diffusers open for max. Blows from them sharply ...

I agree with the opinion of Włodek22. Too high efficiency of ventilation ducts, it threatens to reverse the flow in at least one and suck air from the roof, and there you can do everything. Personally, I saw smoke in the bathroom and the rock sensor in the kitchen that works. My supplement to the suggestions given above for limiting the ventilation capacity is:
1 you live on the top floor - unseal the door to the apartment you will provide warm ventilation air.
2. as the drafts in the ventilation ducts reverse, open the eye briefly or better, corridor doors.
3. in the kitchen, install an adjustable grille and open it only when the hood is working.

The door can't break. I covered the boxes as in the pictures. The string may not be spectacular, but it is. Diffusers in the kitchen and in the large room (one side of the apartment) blows gently. However, in the bedroom and the smaller room (the other side of the apartment) the diffusers from the bathroom grille blow as if more air was still needed to be replaced, despite the fact that the bathroom grille was 3/4 grille. Please look at the pictures. According to me, with such a reduction in the area of grates, the supply of air to the apartment should be stabilized, and it looks like it would be best if I was in the bathroom probably sealed the grille, and I can not do it. I don't know what else to do ...

And why can't you break the front door?

And how should I do it? Cut out the gasket?

You can probably take it out to see what's going on.

zgorany wrote:

The door can't break. I covered the boxes as in the pictures. The string may not be spectacular, but it is. Diffusers in the kitchen and in the large room (one side of the apartment) blows gently. However, in the bedroom and the smaller room (the other side of the apartment) the diffusers from the bathroom grille blow as if more air was still needed to be replaced, despite the fact that the bathroom grille was 3/4 grille.

Maybe the kitchen door and the large room are suppressed by the internal door.
The second thing is that in the kitchen there was reverse thrust, then the riser is cooled down and it takes time to heat it. Similarly, with a reduction in cross-section, the plummet must "cool down" so that the vacuum decreases.

The door in the apartment is locked only in the bathroom. Will these sealed grilles not cause insufficient ventilation in the apartment?

I changed the grilles in the bathroom, set the flow in the kitchen, bathroom, toilet. I have inserted a backflow preventer valve into the hood duct. The entrance door in my opinion is very tight, I did not notice the possibility to remove the seal, unfortunately. Still, in my opinion, too little air gets into the apartment. This is demonstrated by the flows on the diffusers. Windows evaporate after bathing at the bottom seals.

Unfortunately, the wall in which the ventilation chimneys run is icy 16 degrees, which translates into temp in the toilet. Gentlemen, what else can you do?

What I read here is according to this, I have no problem with ventilation in principle.
Air supplied with diffusers should be sufficient as long as they are properly selected for the size of the rooms. The sealing of the grilles should also cause alignment of the draft in other grilles.
Not an interesting situation.
One thing I would advise is the installation of rotary chimney cowls, turbovent. For me, this solved the problem in the bathroom because there was a reverse thrust.
As for heating, I have 47 sqm, 2 rooms. Heaters unscrewed to max 3.5 at a temperature of about -7 * outside and in the apartment 23.5 *. At night we screw to position 3 and in the morning it is around 22.6 *.
In my kitchenette, I have 2 tiles next to each other. One sealed because I have no eaves, the other a full flight and sometimes it blows into the apartment a little. But this happens as the wind blows from the wrong side for the chimney. Unfortunately, the administration urges to install diffusers because they will not put on the second base. Explaining this lack of need because it could cause that in the bathroom, for example, there could be a reverse thrust or vice versa.

On the other hand ... how to check that the capacity in the X box is e.g. 20m3 / h, and in the Y box is e.g. 100m3 / h?

I check the string by putting a plastic breakfast bag on the grid. If it is attracted to the plaid, the string is. In addition, I have a hygrometer and observe the humidity in the apartment. this one is just low for me, from 20 to 40 to 50% max.