I'm sure op has figured this out but for future reference, yes insulate the pipe with insulated flex when drawing in cold air and it won't condense trust me lol. Look at heat recovery ventilators and see how their installed in cold climates. The air being pulled in is not an issue, it's the inside air condensing on the cold surface of the pipe. And yes lowering the humidify will help but unless the pipes are insulated with the proper material it's gonna be a desert before its stopped. Insulated flex has a vapour barrier with insulation in the middle, no moisture will get in the insulation causing mould, again trust me lol. I draw -20 air in and I get no condensing. This is why grow ops ruin houses, very limited knowledge in ventilation that causes mould. If the room is drying out and your in a cold climate then there are two choices, less air brought in or humidify but I myself have only had to humidify once and that was a week at -35, so yup sometimes a humidifier is needed, but also I am old lol. Did I mention I hate Canada in the winter
. Also the push pull thing with fans (inline) is a mute point in that the effectiveness does not change re air flow, what does matter is the effectiveness of what's attached. Carbon filters work better when pulling due to larger inlet surface area and fan motors work better at cooler temps, before the lights if cooled. If someone has a fan curve chart that shows pull versus push I would love to see it, I'm going to set up an test at work to measure the difference using manometer and amp meter next week to see what happens
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