Switching from propane

I would reconsider using propane in your case. Asthma is a major problem with children today. Propane will burn cleaner with less residue in the home. Something like baseboard hot water or in floor heating would be less harmful and could also be tied into solar if $$ permits. Not being able to breath is an horrendous feeling. I would try to save $$ in other ways. Just my thoughts.

I think your question is specific and will do my best. A properly installed pellet stove with proper sealing of every joint in the flue pipe should be cleaner and less polluting of the indoor space than a wood stove burning anything. Airborn dust from ash management as well as smoke from loading is a reality that can only be reduced by proper technique with woodstoves.

I would consider using your forced air/water system and heating it with a wood/pellet furnace in order to further seperate the heater from the living space.

Now does he have the typical asthma or does he have super overly sensitive very risky type of asthma. I am 30 YO and it seemed that about half of my peers in school were "diagnosed" with asthma. Some had a real problem and many did not.

Are you switching from propane to save money? Do you have a budget for us to spend?

I think pellets would be cleaner than wood but I have seen posted here that you do have to clean out the stove
every season or two which would cause dust.

I have mild asthma and the wood doesn't seem to bother as far as the asthma is concerned but it does make my
allergies flare up once in a while which is tolerable. Our cat bothers me more than the wood heat.

You said your son's asthma was mild so it may not even effect him. The bad thing is you won't know till after the install which
could then be expensive to change. You said he stayed where there was already a pellet stove and didn't bother him so may
be ok. Over time you may be able to find out what he is alergic to and just stay away from certain things.

Tightening up your house would be a quicker payoff as mentioned but then you would
still be saddled with those high rising heating bills.

Good luck in your decision what ever you decide.