ᐅ Moisture Around the Vent Pipe of a Mechanical Ventilation with Heat Recovery System
Created on: 28 Apr 2020 14:35
T
Tx-25Hello everyone,
Yesterday we made a concerning discovery.
There was water around the ventilation duct in the bathroom—enough that it was dripping from the ceiling.
Current situation:
Since April 17th, we have been running the screed drying program. The humidity and temperature are correspondingly high. On Saturday, we also applied a primer. So far, we have only ventilated in the morning and evening with shock ventilation throughout the house. The bathroom ceiling is currently covered with drywall and plastered, including directly around the duct. Holes for spotlights have been drilled in the drywall, but no spotlights have been installed yet. The insulation wool (we have a thin layer in front of the vapor barrier) is dry at the spotlight openings. However, moisture can currently move behind the drywall.
Right after painting on Saturday, the house felt almost overwhelmed by moisture. For example, the bathroom window was completely fogged and wet.
Lesson learned: We are now ventilating longer and three times a day. Before, we ventilated less because the installer advised us to maintain warmth.
The ventilation system is not operational yet. The ducts are closed with end caps. The inside of the duct was completely dry.
What could be the cause of the problem? Our installer says to wait and observe. He also mentioned that maybe the vapor barrier has detached from the duct, causing a cold bridge. This is possible, but I find it unlikely. The workers glued the ducts poorly. We even went over every duct ourselves and glued each one again for about two hours. Of course, the work was done by amateurs but with the best intentions and we applied the adhesive multiple times rather than just once.
I haven’t told the installer that we did this extra gluing. If there is a defect, shouldn’t he be responsible for arranging an inspection?
I checked the attic. There is no dampness there. The weather has been good in recent weeks, so it isn’t particularly cold up there—probably around 15°C (59°F). Inside the house, it’s certainly around 30°C (86°F). The attic is insulated with 80mm (3 inches) Pavatex panels. We also insulated the ventilation ducts ourselves with insulation material.
Do you think it’s possible that the water formed on the outside of the duct, still before the vapor barrier, because the inside of the duct might have been about 10°C (18°F) cooler?
That raises the question, why does this only occur in the bathroom? However, the bathroom has always been the most humid room upstairs. Two weeks ago, screed was also poured in the shower area (2m² (22 sq ft)).
What would you recommend? What else could be causing the problem? How should we proceed?
Addendum: Only the upstairs bathroom and hallway have openings for the spotlights. So moisture could move behind the drywall more there.
Yesterday we made a concerning discovery.
There was water around the ventilation duct in the bathroom—enough that it was dripping from the ceiling.
Current situation:
Since April 17th, we have been running the screed drying program. The humidity and temperature are correspondingly high. On Saturday, we also applied a primer. So far, we have only ventilated in the morning and evening with shock ventilation throughout the house. The bathroom ceiling is currently covered with drywall and plastered, including directly around the duct. Holes for spotlights have been drilled in the drywall, but no spotlights have been installed yet. The insulation wool (we have a thin layer in front of the vapor barrier) is dry at the spotlight openings. However, moisture can currently move behind the drywall.
Right after painting on Saturday, the house felt almost overwhelmed by moisture. For example, the bathroom window was completely fogged and wet.
Lesson learned: We are now ventilating longer and three times a day. Before, we ventilated less because the installer advised us to maintain warmth.
The ventilation system is not operational yet. The ducts are closed with end caps. The inside of the duct was completely dry.
What could be the cause of the problem? Our installer says to wait and observe. He also mentioned that maybe the vapor barrier has detached from the duct, causing a cold bridge. This is possible, but I find it unlikely. The workers glued the ducts poorly. We even went over every duct ourselves and glued each one again for about two hours. Of course, the work was done by amateurs but with the best intentions and we applied the adhesive multiple times rather than just once.
I haven’t told the installer that we did this extra gluing. If there is a defect, shouldn’t he be responsible for arranging an inspection?
I checked the attic. There is no dampness there. The weather has been good in recent weeks, so it isn’t particularly cold up there—probably around 15°C (59°F). Inside the house, it’s certainly around 30°C (86°F). The attic is insulated with 80mm (3 inches) Pavatex panels. We also insulated the ventilation ducts ourselves with insulation material.
Do you think it’s possible that the water formed on the outside of the duct, still before the vapor barrier, because the inside of the duct might have been about 10°C (18°F) cooler?
That raises the question, why does this only occur in the bathroom? However, the bathroom has always been the most humid room upstairs. Two weeks ago, screed was also poured in the shower area (2m² (22 sq ft)).
What would you recommend? What else could be causing the problem? How should we proceed?
Addendum: Only the upstairs bathroom and hallway have openings for the spotlights. So moisture could move behind the drywall more there.
A dripstone cave forming during screed drying is not unusual.
However, I don’t quite understand your setup, where there is an open (?) ventilation pipe in the bathroom that could cause condensation?
You should also be aware that conditions in a dripstone cave are not suitable for carrying out painting work properly. Everything is far too wet, not only the screed but also the plaster.
However, I don’t quite understand your setup, where there is an open (?) ventilation pipe in the bathroom that could cause condensation?
You should also be aware that conditions in a dripstone cave are not suitable for carrying out painting work properly. Everything is far too wet, not only the screed but also the plaster.
The pipe itself is not open. It is a standard ventilation pipe for the mechanical ventilation with heat recovery system (MVHR). The ventilation system is simply not operational yet. Since the screed drying has been running since April 17 and the indoor air has become noticeably drier, we have started painting. Before painting, there was no moisture present. Last Friday, I was still working around the pipe (ventilation pipe). Conditions were good enough that the last remaining patches on the plaster had completely dried. So, overall it was relatively dry up to that point. In the mornings, however, the windows (only on the lower level) and the frames were still wet.
I will send a picture shortly.
I will send a picture shortly.
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