Isolating Wood Furnace from Oil Furnace


New Member
Nov 7, 2018
This is the second season using my Englander Wood Furnace. I know that I have a backdraft problem and fitting a plenum damper just isn't going to happen because my AC coil is so big and its too tight in there. House has 2 zones and I am tied into each trunk off the Englander. I have a 24V transformer wired up that only energizes when the blowers on the Englander are running. Is it possible to use that to power a t-stat or relay that would send a 24v signal to the Oil furnace control board and close both zone dampers and also shut down the oil furnace? I have an older EWC control panel and old EWC power dampers. On the control board if I change the damper switch from open to closed, it always keep the last zone called open, no matter what.

For a test, I swapped the power open and power close wires at the EWC Control panel to manually close the zone dampers and had the wood furnace running. I can definitely tell a huge improvement in air flow at the vents. So now I need a way to have those EWC dampers close when the wood furnace is on, but also shut down power to the oil furnace if the wood blower is running. I set the oil t-stat in the house to 63, so if the stove is out or we are not home the oil kicks on.

I will not be doing this, but I need to make sure that something like this is even possible before I contact a local HVAC company.


Minister of Fire
Aug 21, 2013
NE Ohio
Definitely possible...shouldn't even be that difficult. Without spending too much time thinking about it, I would say wiring in a couple relays should do the trick...

Former Farmer

Minister of Fire
Apr 12, 2008
NE Wisconsin
If the oil furnace is not calling for heat, are the zone dampers closed?


Feb 8, 2018
ST. Lawrence Valley N.Y.
As Brenndatomu said in his post above, my thermostats are wired to a relay so that if I am not home in time to put wood on and the propane calls for heat the relay enables the blower on the propane to kick in and cuts out the blower on the wood furnace. After the temp setting on the propane thermostat is reached it switches back to enable the wood furnace.