it's -5* and I am struggling to keep house at 67*...

[CowboyAndy]

First of all, its a Newmac cl-86 wood/oil combo forced air furnace.

Okay, this is a first. We have had temps this low before, but things seemed to be okay. Today not so much.

It's -5*, not much wind. the house is 67*, the blowers are running maybe every 15 min for about 2 min. When I open the furnace door it melts my face off, like REALLY hot.

The front of the plenum is HOT (which is directly over the firebox), but the rear is cold, and that is where the fan switch is and also the oil burner. I mean, theres a MAJOR difference in temp (based on how it feels when I touch it with my hand).

I tried lowering the settings on the fan switch, had set them down to 90 low and 120 high... with dismal results. Tried upping them to 110 low and 150 high, worse. I can feel a cold draft coming from the foundation that is near the rear of the furnace.

My uncle suggested either adding a second fan switch, or relocating the current one.

my questions:

1)what do you guys suggest doing?
2)would adding a second be difficult? could someone walk me though it?
3)would relocating the current one to the frint have a negative effect on the oil burner?

 

[laynes69]

Its hard to believe that the limit/control was located at the oil side, should be centrally located. I would have thought maybe the limit/control be loacted in the plenum, if the 2 share the same plenum. It seems to be that the limit should be relocated also. Is it mounted in the plenum now? I would consider mounting it in the plenum, but I was looking for a manual online for the furnace, or maybe a furnace like it that shares the ductwork.

 

[CowboyAndy]

It IS located in the plenum, at the rear, towards the left edge. Thats where the manual said to put it, and thats as long as the wiring for it is. Yes, the 2 burners share the same plenum.

 

[pybyr]

suggest you try to set the blower control to run over a wider range- as in, "cut in the blower" as soon as the plenum reaches X temp, and keep running until it drops REALLY low.

Forced air is VERY inefficent at moving heat, so you need to move more air, more often.

Especially if you have an old, cold basement where your ducts get cold and pull the heat out of the air for the initial part of the blower cycle.

Infer how I learned these things

Maybe even rig it so that if there is a wood fire lit, and the temperature outside is below __Y__ (play with the variables over time) your blower is always running on slow speed to move at least some heat from the wood furnace, all the time. A "duct booster" as an auxiliary fan to your main blower might even help in that role.

 

[laynes69]

I found for us that 90 off and 140 on was the sweet spot for our wood furnace. Now as long as we had a fire, we were okay. When it would burn down towards the end of the burn, the air was cool. But that was okay, it was warm heat is some heat.