It has been suggested I post here, thanks in advance for any input.

I have a 6 month old bungalow in Ottawa, Canada. It is equipped with a
forced air Bryant model 340MAV natural gas furnace, a Bryant 593C a/c and a
Venmar model 4100 ventilator.

I like to run the circulation fan on low speed continually, especially in
the summer and winter. The furnace controller does not provide for a third
speed to be selected controlled by the thermostat on-auto fan switch even
though the fan motor is 4 speed. Does any one see any major hazards in
adding a double throw, 3 pole relay to allow running the fan at a low speed
when selected at the thermostat and enabling the two highest speeds for a/c
and heat when there is call for temperature change.

The Venmar ventilator is installed with a humidistat for control. I don't
think much of this because in the winter when all is closed up and the
humidity is low it never comes on, just when you would like some fresh air.
I propose to control this by a programmable timer switch. Any thoughts?
Additionally it collects air from ceiling level on the main floor and dumps
fresh cold into the basement, my shop area. What if I connect the fresh
cold into the furnace cold air plenum and wire the furnace fan to run at low
speed whenever the ventilator is on. More thoughts?

Perhaps there is a much better scenario than this that will not cost an arm
and a leg.

Comments and suggestions (serious) please.

Thanks, John.