HerHusband wrote:

Less than 0.2 ACH, ie 4 ACH at 50 Pa with a blower door test?

Well?

It takes 1000 Btu to evaporate a pound of water, and dry wood makes
about 10K Btu when burned

When I burn wood in the woodstove, the air gets dry.

A combustion air supply that dumps into the room vs the stove itself
can bring in lots of dry outdoor air and let more humid house air
leave via the chimney.

The ventilation system noticeably improves the air quality in the house.

Run it with a humidistat...

Given a choice between setting a pan of water on the woodstove, or updating
the house/woodstove/shutting off the ventilation system, I'll choose the
pan of water.

Ignorance is bliss :-)

more house airsealing raise the house RH and REDUCE vs increase
the amount of wood or other fuel burning required.

Short of wrapping the house in a plastic bubble

An outdoor vapor barrier with soggy insulation and rotting studs? :-)

... I don't think there's much more I could do to better seal the house.

You might get a blower door test or do more airsealing on your own,
with a window exhaust fan and a $60 Kestrel 1000 air velocity meter.

Nick