A Novice's heat exchanger question

When using an OWB with a hot air furnace, once the water to air exchanger is placed in the plenum, hot water will circulate continuously through the exchanger. What keeps the burner from kicking in and burning oil?

To be honest, the switch that turns the burner off. I've never taken the time to figure out how to operate my wood side and gas backup simultaneously, mainly because the wood side handles all my winter heating needs. I turn the gas burner off in the fall when I fire up the wood boiler, and turn it back on in the spring when I'm sick of handling wood. That's the best way to be sure....

You could use 2 thermostats, one for the regular HVAC and turn it off, or down, untill needed. And the other just wired to your furnace blower, that way when the house needs heat it just kicks on your blower and away you go. If you leave your regular HVAC t-stat at say 60 degrees, if your wood boiler circuit malfunctioned, then reg system would kick on at 60. A friend of mine does that each winter.

You could use an aquastat on the boiler as well. Wire the gas burner t-stat to the NC contacts. Set it for something like 140F so if there is a fire and the water is over 140F it opens the thermostat wires and does not send the call for heat to the gas burner.

TS

I have to agree with all three replies above... Its really what you are going to be most comfortable with, and how hands-on (or off) you might want your system to be.