Water around furnace: culprit?

Question

Problem:

After heavy rain, water pools around our basement furnace. After climbing onto the roof, I found a mysterious (plumbing?) vent.

This post seemed relevant, but 0.5 gallons comes in after a good rain. It seems more than just a flashing issue.

There are 2 such vents on the roof, in addition to the original chimney.

Question

1. Would putting some sort of cap on top of the vent fix this?
2. What would such a cap be called?

Answer 1

This looks like a newer “vent “ & exhaust, I haven’t seen one quite like that but it looks like a coaxial vent & air supply for a closed system. I wonder if it is rain or a plugged condensate drain that is the problem because that small area would require much more rain to provide what I think you reported even at biblical proportions, I don’t think it has rained that much in our life times. So will a cap help , maybe but probably not. A hvac pro can probably find a problem in short order but I don’t think it could be rain.