I don't understand the open pipe? Is this for combustion makeup air? Is the humidifier inside of the combustion cabinet? Makeup combustion air should not be part of the conditioned air.

The open pipe brings in makeup combustion air. However it's open and constantly blows cold air , furnace running or not. Maybe it brings too much dry air inside and the humidifier can't keep up?? I was hoping the furnace ( Carrier 80% efficiency) had like a intake manifold to connect the pipe to but it doesn't.

The draft from the chimney is bringing in the cold dry air through the pipe. A Field airboot kit would hook up to an oil burner and your pipe. I don't know what would be used for your system.

Outside air during the winteritme usually is at about 70-80% relative humidity, so the air coming in from the pipe is just cold, not dry. Heating this air is what makes your house dry, if you follow a psycrometric chart you see how much you dry out air by heating it from 10 degrees to 70 degrees. By adding humidity not only do you solve dry-air problems but you increase the enthalpy of the air in your home, which is the BTU's of heat each pound of air can hold, just why a hot humid day feels so much hotter than a hot dry day.

As for your humidifier, are you sure the bypass duct has been properly installed? How clean is the drum and water pan? Are you sure the float valve is working properly. If you still need more humidity try a large consolue humidifier. I don't like the other type of furnace humidifiers because they constantly waste water.

What part of the country has 70/80% humidity in the winter? Our current outside humidity in PA, according to the weather station, is 37%

is your furnace locate in a space without ventilation such as soffit vents eve vents etc.if so, in my tennessee local code requires that comustion air be provided via two pipes,one from outside 12" from floor and one 12" from roof or ceiling.also we hardly ever introduce outside air to return side of any residential installation.dont recommend drum type or bypass hums either.normally use fan powered aprilaire.i personnaly agree that steam is best,we just dont use them much,probably due to cost.all that said if you can consistantly get 30% rh with your set up seems like 35% is considered o.k. in most circumstances.

No way cold outside air is 70-80%, more like 40-50%, never the less the bypass type humidifiers and slingers are junk, if you want performance and reliability steam is the way to go, the Nortec ResDelux is a great buy and will keep your whole house properly humidified.

Here is a link that might be useful: Nortec