On an episode I watched this weekend, the one with the cold bathroom and squirrels in the attic, he and the HVAC contractor made a booboo..
He examined a gas forced air furnace with a bypass type humidifier and said the humidifier was installed incorrectly. The alleged problem was that the round duct from the humidifier went to one of the two branchs of the duct work, very close to the furnace. They obviously did it that way because it was the most direct route and within 2 feet of the main plenum on top of the furnace.
He said the way it was installed the humid air would only be going to part of the house. He called in his HVAC guys and they moved it, running it an additonal few feet and making two more 90s to get it into the main plenum.
Only problem is that he was totally wrong. A bypass humdifier just short circuits some air around the furnace, passing it through the humidifier. Whatever goes through it gets sucked in on the RETURN side and then sent out the hot air plenum where it goes to all the house.
His mistake apparently was in thinking the humid air from the bypass humdifier was going INTO the hot air duct. Obviously, the airflow is the other way.
On the same episode, he did a couple of other things that I would consider questionable. He noticed a few joints near the perimeter in the basement that had mold on them. He didn't check for moisture. There was no complaints of water on the basement floor or water anywhere in the basement at all. He dug down to the footers outside then put an inspection cam into the drain tiles at the footer. Camera revealed all was OK. Don't know about you guys, but before I started digging to the footers, I'd check for actual moisture in the joists. Could have been from some problem like overflowing gutters from years ago. BTW, the house had gutters pitched incorrectly.
Then he found the bareest outline in the ceiling drywall of a possible electrical box in the foyer that had been covered up with drywall patch. The electrician found a switch in the foyer that went to it. Don't know about you guys, but I would have just disconnected the wires at the switch and left it alone. He insisted on opening up the ceiling and then they wound up hanging a new $10 fixture that wasn't needed and looked like hell.
95% of the time, he's spot on. This episode, not so much......