Hello. I have a problem that I can`t deal with. I have gravity ventilation in the bathroom and water condenses around the ventilation inlet all the time. Ventilation was done in such a way that about 60 cm of 110 mm PVC pipe is in the ceiling from the ceiling and the rest, i.e. about 50 cm, protrudes above the roof surface (flat roof felt). The part above the roof is insulated with wool and a 160mm plastic pipe is placed on it. All ventilation is in one line. I would like to ask for help, because this is making life more and more difficult. Thank you in advance
from the ceiling, about 60 cm of 110 mm PVC pipes are in the ceiling
Is this ceiling space insulated? Warm, moist air from the bathroom passing through gravity ventilation simply encounters a cold section of pipe in this uninsulated space. Moreover, if there is no roof over this ventilation "chimney", it would also need to be installed.
Thank you for your answer. The canopy is above the ventilation. And the space between the ceilings is not insulated. Could this be the reason? Is there any certainty that this will help?
110 mm of PVC is in the ceiling and the rest, i.e. approximately 50 cm, protrudes above the roof surface (flat roof felt). This part above the roof is insulated with wool and a 160mm plastic pipe is placed on it.
So the thickness of wool insulation is 2.5 cm. This is a bit too little if the wool is "not thick" and pressed moderately into this space, because if there is wool, it should be very dense, and it would be best if this space was filled with polyurethane foam instead of wool.
Added after 37 [minutes]:
Mat.now wrote:
Could this be the reason? Is there any certainty that this will help?
If water condenses from the ventilation, the reason should be found in its ineffective insulation, i.e. the lack of insulation in the ceiling space (replenishing it, unfortunately, involves opening the roof a bit more) and the ineffectiveness of the insulation due to its thickness. If, when insulating with wool, instead of the external pipe with a diameter of 160 mm, a larger pipe, e.g. with a diameter of 200 mm, was used - the beneficial effect would also be greater. Here, it should also be taken into account that the two pipes should be inserted centrally, because then the insulation will have the same thickness on each side, which means that due to inaccurate execution, the insulation thickness in a given place will be lower than theoretically expected.
Will this help? I cannot give my colleague any guarantees here, as other reasons should also be taken into account, such as whether the appropriate draft for this ventilation is ensured. If there is no adequate airflow into the bathroom (holes in the doors, windows that are too tight), there is no proper draft and the air simply "sits" in the ventilation.
What if I now put a 200mm pipe on top of this 160mm pipe? And from what I`ve read, there are different opinions about rotating sockets. Some people claim that it will not eliminate cold "backflow".
I read it and I don`t believe it. It will get better, for some time, eventually moisture will come into play as well. The solution is to simply cover the pipe with wool and that`s it. (From experience, I recommend rockwool with ready-made glue applied), three should be enough.
the reason is not any cold backflow, but lack of insulation in the space between the ceiling and the roof. it is also worth adding wool above the roof.
The discussion revolves around addressing condensation issues in a bathroom's gravity ventilation system utilizing PVC pipes. The user reports persistent condensation around the ventilation inlet, attributed to inadequate insulation in the ceiling space and the cold temperature of the PVC pipe. Responses suggest that the lack of insulation in the ceiling area is a primary cause, and enhancing insulation with thicker materials, such as polyurethane foam or rockwool, is recommended. Additionally, increasing the diameter of the external pipe to 200 mm may improve airflow and reduce condensation. The importance of proper insulation along the entire length of the pipe is emphasized, along with the potential benefits of adding insulation above the roof. Summary generated by the language model.
But it would have to be along its entire length.
