Condensation on drywall
In the last 5 years we have made energy improvements to our 1959 SFD, including air sealing, wall insulation, and changed from gas wall heaters to heat pump mini split. We recently noticed condensation on the interior of a bedroom wall, behind a bed. This is the only place where the condensation has occurred throughout the entire house, and we realized that it is the exact spot where the mini split condenser is installed at the exterior. This bedroom stays around 70 degrees while the outdoor temps drop to the 30s overnight.
We had the mini split condenser installed around the same time that exterior wall insulation was blown in through small holes (from the exterior). I cannot say for sure if they were able to get the insulation added behind the condenser. My best guess is that this space is both lacking in full insulation coverage, but also perhaps the air behind the condenser gets so cold that it excessively chills the wall. Has anyone seen this happen before? What would be our best hope for resolving this issue?
Attached is a photo of the exterior during the insulation work. Orange tape is where they drilled to add insulation. It doesn’t look like they were able to do any spots behind the condenser.
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Replies
That is definitely a lot of airflow behind one of those units. I would not be surprised that it is keeping the local area cooler and possibly even depressurizing the area behind it increasing air leakage from the house.
I would try to move the outdoor unit further out on the mounts and get a piece of rigid insulation on the wall behind it. Have it extend about 1' on either side past the unit.
Hi Akos, thanks for the reply! I thought about the rigid insulation too, and I will definitely be giving that a try. We have a maintenance contract with our HVAC installer so I will contact them Monday about shifting the unit away from the house.