2 cold air returns, one high one low?
In daughter's new house, there is an old woodburner that we had inspected. Passed the test and tech was kind enough to give us an 'all you need to know about woodburners but was afraid to ask' presentation :) Outside of basics, he also looked around her home and came up with a couple of ways to use the woodburner as a whole-home heat source if necessary or desired -- he said it's a shame to waste the hot air that a woodburner can crank out!
He explained about how the hot air from the woodburner could go into the cold air return etc. However for better efficiency for woodburner heat, it would be better to have cold air return higher (hot air rises), right now it is on wall by floor. Turn the furnace on 'fan' and it will spread the heat out of the other ducts.
Then we talked about how a furnace is more efficient with the cold air return on the floor...
He said we could very easily cut into the wall to put in a second cold air return vent near the ceiling -- keep that one open when using the woodburner as a whole home heat source (close bottom one) and visa versa when using the furnace as the whole home heat source.
Has anyone done this? Is it really that easy to add a second vent to the same return?
Hope you understand all of this haha, and thanks in advance for replies!!