I installed the humidifier on the supply plenum and digital guage on return as instructions showed.

I have a furnace that draws outside air into the return duct. This is a new construction home and is pretty air tight. Will the outside air coming in effect the rh reading?

Is there a special configuration for this? I connected the thermostat g wire to the digital meter g wire as instructed.. everything works fine, just the rh is higher than i imagined and i don't think my thermostat does anything with humidity.. maybe i need to upgrade the thermostat?

  • I believe most homes need dehumidification or at least in my area. If the relative humidity is two high reduce the cycle time or turn the system down. Pumping two much moisture into the confines of a "tight" house is a recipe for mold growth. – Ed Beal Dec 12 '16 at 14:03
  • Well I got it because my humidity reader for inside the house has been saying 20% so I imagine the benefits would out weight the cons.. Hopefully anyway. – eaglei22 Dec 12 '16 at 14:41
  • I think the RH reading is being thrown off from the outside air coming in.. So I think, what I need to do is just relocate it to the part of the duct on the ceiling that is drawing air in from the rooms.. Not the plenum of the furnace. – eaglei22 Dec 12 '16 at 14:43

Had to move controller (with sensor on back) farther away to where only in house air was moving through duct. In my house this was at the ceiling as the return plenum area was mixed with outside air and inside..

Sort of like a "T" shape. Top Right side of T duct brought air in from outside, left side brought air in from return vents, and the middle (body of T/ Plenum) is where the air mixes together.. And of course outside air will have higher humidity, so it was messing with the readings.

Hope this helps someone else one day.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.