Panasonic ERV cold weather issue.
Not long ago I installed a Panasonic Intelli-Balance 100 in my basement. It is a stand alone setup. It does not tap into the current hvac at all. I used the Panasonic FV-WC04VE1 exterior vent cap. It’s styrofoam that splits in two and has exhaust on one side and inlet on the other. The system has been great through summer and fall. The air quality is much better. But as soon as the temperatures started dropping below freezing the duct that brings fresh air from outside has had a lot of condensation. I did exactly as the directions said and used insulated flexible ductwork attached to the ERV and the styrofoam pipe. I taped it with foil tape. I live in Pennsylvania so the cold temperatures are just starting. I know I had it sealed good because I noticed the insulation looked more puffy than the exhaust side. So I undid the tape and water poured out of the insulation. It wasn’t just damp it was completely soaked. But the tape held all the water in. None leaked out until I pulled the tape. The exhaust side was perfectly dry. Also the styrofoam was dry. Just the flexible insulated part was soaked. Also the inside of the ERV was completely dry. So I used new insulated duct and made sure to tape it good. It went down to 25 degrees last night and I checked this morning and the insulation was soaked. The ducts leading from ERV to the outside are only about 3 feet long and go pretty straight so I don’t have much insulated duct to worry about. I did exactly what the directions say. What else can I do to stop the condensation? The unit doesn’t have a condensation drain but it is intended to use in the cold weather. Also the basement is currently 68 degrees and 40 percent humidity.
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Post some pictures of both ends. Moisture is getting in somewhere, means you have an air leak into the insulation.
Flex duct needs to be sealed in two places. First you need to tape the actual duct to the fittings on both ends and then you need to tape the foil over the insulation to the wall cap and the unit. If both those connections are air tight, you should not have any condensation.
I did tape the inside duct and then also the insulation. It was a pain to get the tape off because I taped it so good.There is not much to see in photos. I currently don’t have the duct on the inlet side. I stuck a foam ball in the styrofoam end to block cold air. You can see how the exhaust side is ran. It was the same on the inlet side before I took it off. The duct is only about 2 and a half feet long.
I had a very hard time getting the sock taped in between the vents on the tandem connection.
What I found works is to get a length of tape and peel half the backing off. Now pull the unpeeled end and the backing from the other side between the the two legs. While holding the peeled end, pull on the backing to remove it from the tape. This lets you position the tape and sock where you need it without having it stick to anything until you pull the backing.
Also check if there is an air leaks between the foam collar and the hard pipe on the unit. Turn on the unit and plug the exhaust with your hand, you should feel if there are any leaks somewhere there.
I think the problem might be is the tandem vent is rated for only 50CFM. There is a fair bit of pressure in there if you run at on boost which is finding some small air leak path.
I removed the shelf below the ductwork. I am making sure everything is very sealed up. I generally have the ERV running on a low setting. It seems to keep the air quality great with little effort.