Not getting much heat

[.358 win]

It may help to investigate a radon vent's function.. I don't have the specifics. But it sounds like there may be similarities.. Others in this site I'm sure know the how and why, or why not.

 

[sean donato]

Sean, that is not really why they are installing those outdoor inlets. It is not because the houses are tight, it is because people are buying furnaces because of their efficiency ratings. Fuel is expensive, and people know that it will pay off in the end to invest in a better furnace.

You cannot get an efficient furnace without bringing in outside air. The more efficient furnaces capture so much of the heat that they condense the exhaust gases and must use PVC pipe to capture the runoff. A conventional flu would soon rust out, and the condensation would run downhill into the furnace. So long as you are putting in one pipe to capture the condensed exhaust gases, you might as well increase your furnace efficiency by bringing in outside air, too.

I do not know how they rate furnace efficiency, but it is a sure bet that sucking cold air into the building to feed the furnace is not going to be improving that efficiency rating at all. Hence, the outside air.
Higher efficiency rating = higher sales & more profit.

Back when I was young, fuel was cheap, people did not think of furnace efficiency, and the corners of the house got cold because of all the incoming cold air. In fact, the heat exchangers of furnaces were engineered so as to leave enough heat that the exhaust gases would go up the flu and not kill everyone in the building with retained carbon monoxide. My how times have changed!

The first experience I ever had with high-efficiency furnaces was when my brother (a pipefitter) installed what was called a pulse furnace. He had to install the air inlets and the air exhaust. As I recall, that was back in the middle to late '80s, and that was quite the exotic furnace to install at that time. It made too much noise, however, and fell out of favor with the purchasing public.
It sounded like a moped running in the basement!

Thats very interesting, I hadn't considered they would be removing that much heat they would need to worry about condensation. Guess I'm living like a dinosaur lol.

 

[pdqdl]

The furnace in my house requires a drain pipe to the sewer lines. It catches nearly all the humidity before it gets vented outside.

Some of the modern furnaces have an inner & outer pipe arrangement, so that the incoming air is warmed by the outgoing air. This captures just a little more heat from the exhaust gases, and allows for the installation of a single round pipe to outdoors, rather than just one.