New member wood furnace backdraft damper install

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brenndatomu

Minister of Fire
Aug 21, 2013
6,537
NE Ohio
There may be a "circulate" setting on your furnace control board too...it just runs the blower at low speed all the time, until the heat or AC kicks on, then it acts as per normal...
 

01_Sentea2.0

New Member
Sep 7, 2021
33
WV
I have a schematic for my gas furnace blower. I don't see the circulate one listed for mine. Some of these wires I have no idea what they are used for.

20211106_225518.jpg 20211107_001243.jpg 20211106_225548.jpg
 

brenndatomu

Minister of Fire
Aug 21, 2013
6,537
NE Ohio
I have a schematic for my gas furnace blower. I don't see the circulate one listed for mine. Some of these wires I have no idea what they are used for.

View attachment 284960 View attachment 284964 View attachment 284966
Yeah I'm not that familiar with them...I think often times there is a little switch on the board that you flip to activate the circulate mode...see anything like that? Your circuit board pic didn't get the whole board so it may be on the other part not pictured?
If you have the manual (or can look it up) for your furnace it would say if it has this capability...
 

01_Sentea2.0

New Member
Sep 7, 2021
33
WV
Yeah I'm not that familiar with them...I think often times there is a little switch on the board that you flip to activate the circulate mode...see anything like that? Your circuit board pic didn't get the whole board so it may be on the other part not pictured?
If you have the manual (or can look it up) for your furnace it would say if it has this capability...
I do see a CIR white wire terminal going to the circuit board from the blower motor. Does CIR run on low speed?
 

brenndatomu

Minister of Fire
Aug 21, 2013
6,537
NE Ohio
I really don't know...would have to look up in an owners manual...I know just enough about this stuff to be dangerous... ;lol
 

01_Sentea2.0

New Member
Sep 7, 2021
33
WV
Do you have any part numbers for the 120v relay coil that I could use by chance? I'm seeing so many different relays such as spdt and dpdt. I'm unsure on which one that I could use.
 

brenndatomu

Minister of Fire
Aug 21, 2013
6,537
NE Ohio
Do you have any part numbers for the 120v relay coil that I could use by chance? I'm seeing so many different relays such as spdt and dpdt. I'm unsure on which one that I could use.
I'd look for something along these lines...these have the base with it...not new though, just FYI...
 

01_Sentea2.0

New Member
Sep 7, 2021
33
WV
I'd look for something along these lines...these have the base with it...not new though, just FYI...
Okay thank you. Do I need a 24v on the other side going to the thermostat wiring? Like a 120v relay to 24v built in transformer.
 

brenndatomu

Minister of Fire
Aug 21, 2013
6,537
NE Ohio
Okay thank you. Do I need a 24v on the other side going to the thermostat wiring? Like a 120v relay to 24v built in transformer.
No, this relay is just being used to complete the circuit, just as the gas furnace/AC thermostat does when it calls for heat/AC...
 

brenndatomu

Minister of Fire
Aug 21, 2013
6,537
NE Ohio
Sorry one more question. Do I tie one one NO contact to R and one NO contacts to G?
I guess I'm not sure how to read this...if you mean one side of the NO contact to R and the other side of the same contact to G, then yes...this way when the relay fires, it completes the circuit.
Pick a side, left or right (DPDT) R goes the "COM" terminal, G to the "NO" terminal on the same side...or you could go G to COM, R to NO, as long as it is on the same contact set (same side) as shown below, each side, COM, NO, and NC is considered a contact set.
And whenever wiring, remember that the diagram always shows everything in its "normal", or unpowered state (as it comes out of the box, so to speak) unless otherwise noted (which is unusual)
I suppose this would have been a little less confusing using a SPST relay too.
And while we are at it, the "coil" terminals of the relay are not polarity sensitive, the hot and neutral wires can go to either terminal of the coil (one to each terminal)
iu
 

sleewok

New Member
Jan 27, 2021
33
USA
Going back to putting the ba draft damper on the return... Why does it need to be powered? Wouldn't the initial pressure from the wood supply push it closed? Then when the gas furnace is on it would pull it back open. I'm also curious how this method is safe enough for the coils. I'm in a similar situation with my setup for my second heat pump air handler.

I have a damper installed on my first air handler that is connected to my wood furnace. I'll stick my anemometer in and check the temp right before the damper I have installed. I'll report back!
 

sleewok

New Member
Jan 27, 2021
33
USA
No, the damper is blocking its path to go anywhere other than where you want it to go, up into the house through the supply ducts
With the damper closed the furnace becomes a "dead end" so to speak, as far as air flow goes...so with the airflow, goes the heat...I mean the AC coil and tray may get warm, but no warmer than they get when the gas furnace runs...
I took readings with my anemometer to see what the air flow and temperatures look like right before a damper put in the central air handler. In my setup I have my heat commander wood furnace supply running three 6" supplies to the main plenum. They enter the central air handler plenum about 2 feet from the damper ( that sits on top of the air handler supply (right above the a-coil)).

From what I can tell it doesn't seem wise to put a damper at the return and expect to "protect" the a-coil.

The following readings are with my wood furnace only running for about an hour. The temperature is still climbing. The air flow at the damper is equivalent to piping a 4-5 inch duct directly towards the a-coil. Furthermore, the supply I am providing is undersized for the existing ductwork. This means that I have low pressure in the ductwork. My positive static pressure reading was around 0.04. With that in mind, if someone has undersized ducts then the airflow back towards the a-coil might be even higher.

F-ASVUmXKqsWXKboIGkvdCIIZBkMcAZaklJvXJAPiLguW7yaP1FJ8FoW3CC3JYMwNHfrXekqQjIUxhk6YoTmt45wpxDweKt96r8n_kUAPWI10B0tPNCLto7MmbhGXgtykfp_F9r7x3P7uGR-Ayf5_h4xcwsI6ft8--9UdSQvYX5cuW-CtEXJrxhp-w7hra6JYnL5GYlAtUfQVZgeW_XFDa0lFK-3AJwf7f6W69YzUZUDQiggTLqeQ9Uo__oZul8KQAYEwEi9fPjC_FBa7GUxJ0gomiP4AwS4odzgDfNhnNEehEBnOxH4gmA1B0KXtdRx9OFWO4hANpxvz_FeWFxLwy_Vl7AwCd0APBv21X1bQMC8mvcQ5wtSfGkGFkyofXI9qHsDRp0VMNU1Ms_MMrarWUmdQkPb1We7WVvTFMhjLjWpIWxiMY7YOCZCeceNvTGICtPTFbkQp1W36DMrOVyvAYo3UEHuzb9gPE8dyAK0Zm1XcKOXcwc8vxIb_T1hvvmhWTVfKZ0McS64rH7QVuQZg2nPeGD9Hc4YEI-yyR9_HIeWrQTqzy3OSVDtbVULd2-Gj_pdG4dFOMMhYlHHvBfUd6AcLohtmCj_pR95qQ95Faddxb-I8Vc7d6mcTMrgBiYmanfxlaVxZWkFZ0xU19dUQ6Cl7p9COd7hvxWeLNo0oVjAndLX08ydG3Tq2GpnCy0aIBqQKOTHuB6xoQdGSeuLqutD0Q=w405-h876-no
 
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01_Sentea2.0

New Member
Sep 7, 2021
33
WV
Would manually pulling on the thermostat on the back of the Englander cause the switch not to work right.? The switch is closed when the power is off. When I shut my door of my gas furnace the blower turns on like I gave it power. Was just trying to see if it was going to work before I put everything back together.