on a heating pm today, the lady was telling me that she had the vent pipe replaced last year on her 4 year old rheem furnace. i asked why...
she said "the remodelers said it was not the right kind of vent for the furnace. it was a pipe that went up for 3-4", then had a gap, then it continued with another pipe with s small hood on it... you know, like a water heater!"
to be sure, i asked, "you mean there was a chunk of vent pipe missing right here? and you could see this green coil box thru the gap in the pipe?"
the original contractor has 2 or 3 trucks, see them around town now and then... i'm still at a loss for words