Close the combustion air...

[David Hays]

Heck we don't need any combustion air. It's too cold and freezing the water pipes.

Another question, which came first? The chicken or the egg. The tinner or the plumber. I would say the tinner.

[David A. Andersen]

As it should be.

[Greg Keene, CPI]

I see that up here in the mountains all the time.

[Christopher Currins]

Originally Posted by dhays

Heck we don't need any (additional) combustion air.

If this unit is in an unfinished basement, as it appears, it shouldn't need an exterior source of combustion air.

That pipe was most likely installed if/when basement is finished and the furnace/water heater are enclosed.