Wood burners bible? (new to wood burning) need help with furnace operation

[CowboyAndy]

New chimney liner - check
New Newmac CL86C wood/oil combo furnace - check


Now, I am completly new to wood burning. What are some of the things I MUST know?

A question I have:

how should I handle the first fire in the furnace?

 

[relax]

use only wood if you can ...dont know anything about your set up...burn baby burn ZZZim

 

[Jags]

author="CowboyAndy" date="1222377168"
how should I handle the first fire in the furnace?

Not sure how YOU should handle it, but I handled it like the FBI, Mother in law, and IRS was gonna show up all at the same time. Nervous, jittery, nail bit'in, lookin' for any kinda trouble, bouncing around like a real ding-dong.

Everything went fine, and I suspect that yours will to, but that doesn't really take the edge off of lighting a FIRE in your HOUSE for the first time. Mind you, this was several years ago, and I am much more calm now.

Relax, double check everything, follow the break in routine in your manual (if it has one), start small and build some confidence in the appliance. Then GIVE'R HELL.

 

[mranum]

author="CowboyAndy" date="1222377168"
how should I handle the first fire in the furnace?

Not sure how YOU should handle it, but I handled it like the FBI, Mother in law, and IRS was gonna show up all at the same time. Nervous, jittery, nail bit'in, lookin' for any kinda trouble, bouncing around like a real ding-dong.

Everything went fine, and I suspect that yours will to, but that doesn't really take the edge off of lighting a FIRE in your HOUSE for the first time. Mind you, this was several years ago, and I am much more calm now.

Relax, double check everything, follow the break in routine in your manual (if it has one), start small and build some confidence in the appliance. Then GIVE'R HELL.

Yup I can relate to that %-P I was as nervous as cat in room full of rockin chairs.

Got all my break in fires done and then the other night when it was like 60 outside the wife says...

"Now I know your NOT going to light a fire tonight are you?"

I just said no of course not, when she left the room and came back in there was a fire rollin. I just got that, " I should have listened to MOM look" :coolsmile:

 

[begreen]

Moved to the boiler room for more targeted responses. Burning in a wood furnace takes a bit of learning. Hopefully some of the seasoned furnace folk here will be able to provide some guidance.

 

[cricco]

along for the ride........

 

[jebatty]

Wood stove, boiler, furnace, etc. is not rocket science. Take the time to think what is happening. Since I too know nothing about your setup, this is generic.

Fuel + oxygen + heat source = combustion. Once combustion starts, it will self-sustain so long as fuel and oxygen are present. Your two controls, therefore, are fuel + oxygen. Fuel you control by how much, how dry, size of splits you put in the furnace. Drier will burn hotter and faster than wetter because you have less water to evaporate off. Smaller splits will burn hotter and faster than larger because there is more surface area to combust.

Oxygen you control by your furnace dampers, your chimney configuration and outside conditions. Not easy to change an installed chimney and outside conditions, so your only real control is your damper(s). More open means more oxygen and hotter and faster burn. Less open is the opposite.

Most who burn wood have some sort of a temperature reading that tells them either how hot the stove is on the surface or how hot the exhaust gases are in the flue. Thermometers generally are magnetic and stick to the surface being measured, or have a probe which is inserted into the space to be measured. Don't consider a thermometer to be an exact or accurate reading but only as a relative reading so you can see what combustion process is producing what relative heat.

Wood normally ignites at about 500F. So a minimum burn temperature inside the furnace will be 500F, which is too low to produce an efficient, creosote burn. From 500 to about 900F normal combustion continues. From about 900 and up secondary combustion occurs, which is the burning of the volatile gases driven off but not combusted during the ordinary burn process. This typically is where the stove/furnace is burning more efficiently and producing little if any creosote.

As temperature rise towards 1500-2000F gasification occurs, and the burn process becomes entirely different. Few if any normal stoves and furnaces operate in this range, and only gasification boilers (not all wood boilers) are designed to operate in this range. I'm assuming you do not have a furnace designed for gasification burning.

With your thermometer, and when burning wood, my great preference is for a flue thermometer, either magnetic surface or probe, installed about 18" above the flue outlet of the stove/furnace. If a magnetic surface thermometer, rule of thumb surface flue temperature should be about 300-450F. The "sweet" spot (good secondary combustion) is at 350-375 for my stove, until the wood burns down and only coals are producing heat. Given inaccuracies in thermometer and individual stove design, the "sweet" spot for someone else may be higher or lower. Rule of thumb interior flue temperature with a probe thermometer will be about twice this, or about 600-900F.

As interior flue temperature rises to above about 1000 a dull red glow, likely only visible in the dark, will become visible on the steel surfaces where this temperature exists. The glow will get brighter as the temperature rises. I do not like to burn my stove at this level for two reasons. I think there is some element of danger at these higher temps, but importantly at these temps I'm wasting lots of heat that is just going up the chimney. A properly sized stove/furnace for the space to be heated should not have to operate up in this range. As to danger, a Class A chimney is designed to operate continuously at about 2000F, so these higher temps should not pose a chimney problem. But why waste heat.

During the bulk of the wood load burn interior flue temperature definitely should not be less than 300F, and more likely should be about 500-700F or a little hotter. Condensation will occur at less than 300F, and with this temp and a normal wood stove/furnace I believe you are exhausting lots of unburned gases and particulates which will produce creosote in your chimney. Interior flue in the 500-700F should mean that you are combusting most of the fule and creosote formation shold be minimal. With a flue surface thermometer, reduce these temps by 1/2.

A new stove/furnace takes some break-in time to dry out or condition the refractory, if any, the paint, and to work out the creaks and groans from expanding metal. Follow your manual as to break-in procedures.

Wood stoves/furnaces are safe, efficient and easy to operate, with some experience. Your biggest problems/dangers will come either from a stove burning too cool or burning too hot. Find your "sweet" spot and aim for that in enjoying your new furnace.