hvac
Water comes down the PVC vent pipe to my furnace and leaks out at the elbow. Water seems to come even when the furnance is turned off. I had a furnance man come out. He said there is a leak at the roof, as it had been raining.
Now, it is days after he left. We have not had any rain.
What type of repair person would I need to call?
The best way to combat the condensation problem is to insulate the riser duct, aka metal duct, that is causing the problem. There are several ways to do the job. The best way is to use a vapor-barrier & spray-on foam insulation, but that can be costly and messy, unless done by a professional. Another is to use Rock-wool to insulate the duct, but often there is not enough room in the wall to use it. The insulation that I prefer to use is a Duct-wrap. It looks like bubble-wrap with small "bubbles" sandwiched between 2 layers of foil-lined plastic. It all depends on how much money you want to spend and how much space there is between the duct and the drywall.
The short-term solution, is to install a duct-wrap. It is available at home improvement stores in the building products department in the insulation section. It generally comes in various lengths at a 4 foot width & can be cut to size with scissors (or a razor-knife, if you are careful). To install it, simply measure the distance between the studs and add at least 12 inches to tuck the insulation behind the duct OR add 4 inches & staple it to the studs like traditional fiber-glass insulation. Cut the duct-wrap to size. You will also need to get metal (duct) tape to seal the seams between the upper piece and the lower piece of duct-wrap. It has a paper-backer to keep the glued side from sticking to itself. You will need to peel the paper-backer off when you install it.
The Long-term solution would be up to you. You could hire someone to take apart your existing ducts and insulate them or you could do the job yourself, either way that is the only solution to your problem. And by the way, cutting a hole on the wall will only make matters worse by giving the humidity a direct path to the now un-insulated ducts.
That pipe looks like an air intake.
All "direct vent" style appliances (high efficiency on-demand water heater, gas fireplace, etc.) have an isolated air intake and it is common to have it suck in air from outside the building so as not to force air infiltration through doors, windows, etc.
Indeed, that is ugly. Our fireplace and tankless water heater have something far more elegant:
The stack on the left is a natural gas tankless water heater. The right is a direct vent natural gas fireplace insert.
Best Answer
You likely just need caulk from a poor HVAC guy install using flat metal that is now sagged (needs to be crowned) & letting water in as well as causing condensation water whenever the furnace runs. If you aren't comfortable with getting on the roof to see if you just need caulk, then absolutely get a Roofer to address it.