External air from Earth tube and Chimney

Looking for your opinions on 2 topics.

If the primary was external, specifically from a earth tube? Would that help or hinder?

What effect would an chimney fan have? Would it end up sucking the heat out before it goes into the mass?

Hi Robert,   External air has been discussed a fair amount here, having its pros and cons but typically favouring the cons. The best place I found that covers it well is here: the-outdoor-air-myth-exposed

In the RMH world, a chimney fan is only necessary (for some people) when you have poor draft at startup with a cold mass and want to give a little boost at the beginning of a burn, then turned off.
A bypass is a more low -tech solution that is hard to beat for its simplicity and reliability.

Hi Robert;
I'll take a try answering your questions.
#1) Using an earth tube to supply your Primary air.
I can see no benefit from this.  I'm not sure how one would plumb such a thing. But my concern would be volume.  
It takes a lot of air for an 8" J tube.  
What were your thoughts about this? What was your idea?

#2) Using a chimney fan is it a good idea?
Well the answer is Yes and No !   A fan is sometimes  necessary to start the draft until your chimney heats up.
Running one all the time is not a good idea.

Designing and installing a bypass gate to preheat your chimney is a much better way to kick start a dragon... no electricity needed!