Not enough info, but it sounds like you have all the right components, just not set up properly.
Are you able to find the original installer?

 

components

No idea on installer bought house 2nd owner

 

Mild outdoor temps you’re not running the A/C.
I recommend a whole house dehumidifier with outside air hookup.

 

"Big insulated pipe" is a relative term. What's the diameter?

Bottom line is that fresh air is important, but too much will show up on your utility bill. And/or cause comfort issues. Then throw in that all air that enters the home needs to exit the structure; some houses are much more leaky than others.

This is why the first reply you received stated not enough info for us, there can be more to this picture than many believe or understand.

Hi hoping i can get some help?I have a house built in 2003 in central Canada.I have i high efficient furnace so i have 2 pipes that goes outside i assume one brings fresh air in for combustion and one to exhaust out.I also have o big insulated pipe running from out side to middle of cold air return.Question is i am having high humidity in house right in basement of 70 so running a dehumidifier now.Do i really need that insulated pipe bring air into return in summer?Is it not bringing all that humidity from outside into the house?Thanks in advance

 

Hi my pipe is a 6 inch insulated pipe running from out side to cold air return.Sometime in basement humidity is like 70.My furnace motor runs all the time but on slow speed when not in heat or cool cycle.Question in summer if fan running all the time am i not bringing in humid air into house all the time?Buddy of mine that installs furnaces told me to disconnect it from cold air return and seal the hole.I would have no fresh air entering the house thats not good either?