Air intake on NC32

[wagdog]

I’m trying to find out as much as I can about the NC32 stove I have.

My understanding is it’s an update to the NC30.

From what I’ve seen online regarding the 30 is it had a primary air intake in the bottom front of the stove (doghouse?), a window wash intake, and 4x secondary burn tubes across the top of the stove with 2 baffle boards resting on the tubes. All of the intakes were fed by a single intake in the bottom back of the stove and controlled by a push/pull handle.

As near as I can tell, the 32 has no primary air intake or window wash intake. It looks to me as if the only air going into the stove is through the 5x secondary burn tubes on the top of the stove. The intake is also located at the rear bottom of the stove and also controlled by a single push/pull handle.

I’m just interested in learning as much as I can about how the stove operates. I feel like I’ve got a good handle on running it but always want to learn more. If anyone has any insight to the design and operation of the 32 I’d appreciate it.

Thanks for any input.

 

[FTG-05]

Tagged for info. MY SIL/BIL are interested in this stove.

 

[Highbeam]

On the nc30 there are no less than 4 separate air holes feeding the stove and only one is controlled by the push pull intake control. Works great.

 

[wagdog]

On the nc30 there are no less than 4 separate air holes feeding the stove and only one is controlled by the push pull intake control. Works great.

So the other 3 are always open on the NC30?

I’m not seeing any other intakes on the NC32 aside from the secondary intakes. This doesn’t make sense to me, but then again, these new style stoves are completely new to me.

 

[NickW]

The NC30 has 2 round holes in the bottom front behind the legs, a rectangular one centered in the bottom back, and the primary that is adjustable by the slide lever. Air can't be 100% shut off, but shutting the primary all the way has always (so far...) allowed me to choke it down enough to control it. Some folks with really strong draft put magnets over the other holes to keep it controlled.

 

[wagdog]

I’m not seeing any other air going into the box with the exception of the secondary burn pipes. Here’s some pics of the underside of the stove.

The first is the air intake in the rear. The first section down goes to the front. The second section is for the ash pan.


The next pic is from the front with the ash pan removed. The hole is for the plug inside the stove.



The push pull handle rides in that first section and opens and closes over an opening in the rear.

I can see in the rear of the firebox where air is distributed to the secondary tubes.

What I can’t see is anywhere else for air to enter the firebox.

Does it seem possible that the secondary tubes are the only air intake on this stove?

 

[NickW]

NC30...

Hole behind legs... cobwebs are an upgrade and cost more...

Rectangular hole behind primary intake near blower.


I believe the NC32 doesn't have a leg or blower option.

 

[wagdog]

Thanks for those pics @NickW

What-do-ya-know, I did locate a rectangle cut in the back near the main inlet.


What I don’t know is where in the firebox it comes out.

 

[begreen]

Thanks for those pics @NickW

What-do-ya-know, I did locate a rectangle cut in the back near the main inlet.

View attachment 275648
What I don’t know is where in the firebox it comes out.

A guess would be that this is the secondary air? In the left and right front corners are there small holes?

 

[SpaceBus]

Seems strange to have intakes that aren't connected to the OAK

 

[begreen]

Seems strange to have intakes that aren't connected to the OAK

It's not uncommon, same on some Morsoes.

 

[SpaceBus]

It's not uncommon, same on some Morsoes.

I assume then just a small amount of air enters through that opening? I assume the same with other stoves.

 

[wagdog]

A guess would be that this is the secondary air? In the left and right front corners are there small holes?

I don't see any.

I also can't feel any air going through that rectangular hole. There is definitely air going through the main intake.

My primary reason for trying to learn as much as I can about the stove is I've had a couple of times where it started to run away. I'd like some kind of strategy to keep things under control. From my past 25+ years of wood burning experience, that strategy has always been "shut off the air"! That doesn't seem to work with this stove. I was able to get things under control by opening the cleanout door a few times to slow down the draft and, strangely, opening the front door of the stove for a few seconds, a few times.

 

[begreen]

strangely, opening the front door of the stove for a few seconds, a few times.

That works well because it reduces draft, then the firebox then gets flooded with cool room air and the draft is no longer pulling air through the secondary tubes.

 

[NickW]

According to the wise fellows here, I was told the rectangular hole feeds the secondary tubes and the holes behind the legs feed the doghouse. As it heats up the flue and creates more draft I assume that pulls more air in the fixed holes. I don't get the strong jets of flame from the tubes until it's heated up well even though I will have secondary combustion before the jets kick in. The doghouse gives a draft to the front even if it's not raging.

 

[NickW]

Shutting of the air has been effective at controlling it for me, but it is slow. If I start getting much over 700 stt, I'll shut the air completely. Then the temps go up more but there are no primary flames. It'll keep raging for a while (15 minutes or more), then come down. I'll open the air to about 1/8 open before the secondary's die, usually at stt of about 550; and it'll usually come back up and cruise at about 600.

 

[wagdog]

I called englander.

Here is my understanding of what they said:

The primary air goes along that channel on the bottom, along the bottom front under the door, up each side and is then deflected down the glass. This picture appears to show that:

looking underneath the stove, I can see where these channels are welded.

The push pull handle effects the primary air.

I didn’t ask, but I think the rectangular hole is for the secondary tubes.

What the tech did say was if the stove is over firing due to excessive draft (like I’m experiencing today with high winds), is shutting down the primary will force the secondaries to burn hotter. This is due to it pulling more air through the secondary and *could* result in temps rising. I tested this and DIDN’T find it to be the case; adding more primary air to an already very hot stove made it get hotter. What did work was the aforementioned technique of opening the door a few times.

I may need to explore the adding more primary air option more though. Maybe I should have pulled the handle all the way out?

So, I’ve still got more to learn, but I feel like I’m making progress.

 

[Highbeam]

I called englander.

Here is my understanding of what they said:

The primary air goes along that channel on the bottom, along the bottom front under the door, up each side and is then deflected down the glass. This picture appears to show that:
View attachment 275663
looking underneath the stove, I can see where these channels are welded.

The push pull handle effects the primary air.

I didn’t ask, but I think the rectangular hole is for the secondary tubes.

What the tech did say was if the stove is over firing due to excessive draft (like I’m experiencing today with high winds), is shutting down the primary will force the secondaries to burn hotter. This is due to it pulling more air through the secondary and *could* result in temps rising. I tested this and DIDN’T find it to be the case; adding more primary air to an already very hot stove made it get hotter. What did work was the aforementioned technique of opening the door a few times.

I may need to explore the adding more primary air option more though. Maybe I should have pulled the handle all the way out?

So, I’ve still got more to learn, but I feel like I’m making progress.

That square hole in back feeds that secondary air riser pipe that you see in the middle of the back wall in the firebox. It's full throttle all the time and a big hole. The draft pulling from the chimney is sucking air into the stove to feed the fire. If you assume that this amount of suck is constant as you close the primary air then more air will be sucked through the secondary hole to meet the demand of the suck. The air control can be considered a ratio tool and there should always be an excess of secondary air to support clean combustion.

If you still can't control the stove with the primary air closed all the way and it's so bad that you would consider opening the loading door to cool things off then you almost certainly need a key damper in your flue to reign this thing in. Hot stoves burn clean so the manufacturers are designing them to burn really hot and take the ability of the operator to control output away. Some stoves completely did away with the intake air control! The key damper allows you to have some control or to leave it wide open for a high draft experience.

 

[wagdog]

then you almost certainly need a key damper in your flue to reign this thing in.

I don't like key dampers. I don't know why, but I just don't.

But, yeah, I'm getting there, unfortunately. I will be installing one next time I get a chance to fully cool down.

I feel like the operator should be completely able to control the air intake of the stove. I'm beginning to understand the concept that these new stoves are built under, but I still feel like there should the ability to shutdown the intake air, not slow down the output.

Edit: Also, I've figured out how to build a fire that isn't as hot on high wind days: build it in the rear of the stove.

 

[NickW]

At what temp are you considering it getting away? I switched from an old smoke dragon last year and was freaked out about the temps at first. Took a while to work up to full size loads and hitting stt of 700. Many of the guys here hit 750 stt every load with their NC30's and don't even blink at it. The nature of how the entire system works is very different from old stoves.

 

[wagdog]

At what temp are you considering it getting away? I switched from an old smoke dragon last year and was freaked out about the temps at first. Took a while to work up to full size loads and hitting stt of 700. Many of the guys here hit 750 stt every load with their NC30's and don't even blink at it. The nature of how the entire system works is very different from old stoves.

I'm more concerned with the flue temp, which I've had over 950, more like 1000+ (measured with a probe). When I see those temps, I want things to come down fairly quickly.

My STT has been up over 650, probably closer 700, maybe more. I'm using a magnetic thermometer of questionable accuracy.

I feel like the stove can take the periodic abuse, but I don't like seeing the flue stay that hot for too long. We have a stainless liner, but I'm still not a fan of things getting that hot.

 

[Highbeam]

I don't like key dampers. I don't know why, but I just don't.

But, yeah, I'm getting there, unfortunately. I will be installing one next time I get a chance to fully cool down.

I feel like the operator should be completely able to control the air intake of the stove. I'm beginning to understand the concept that these new stoves are built under, but I still feel like there should the ability to shutdown the intake air, not slow down the output.

Edit: Also, I've figured out how to build a fire that isn't as hot on high wind days: build it in the rear of the stove.

There are a couple of reasons to dislike key dampers. It is harder to clean the pipe, though I’ve been told the sooteater just goes right past it. They can also be abused, meaning used too aggressively to essentially defeat the ability of the appliance to burn as clean as it was designed. You only want to use the key damper to regain control, not to smolder a fire.

The good news is that they’re cheap, available, removable, and completely necessary if your chimney is over drafting your appliance.

Even though my nc30 is totally controllable I added a damper after several years because it was blowing all the heat up the chimney resulting in inefficient and short burns. When a good fire gets chooching with the damper open I can hear it roaring. As I close the key damper that roar goes quiet and the flames, especially the secondaries, slow down. Still a hot stove but much longer burn times and cooler flue temperatures. I’m happy with it.

Just fired one up for the evening.

 

[MAD MARK]

Took a while to work up to full size loads and hitting stt of 700. Many of the guys here hit 750 stt every load with their NC30's and don't even blink at it.

This is right. Took a year but I don't start messing with much til the IR gun reads over 800. The temp gauge reading 750 I'll just walk away.

 

[SpaceBus]

If you turn the stove down earlier in the burn you will have less robust secondary combustion. This is how I control both of my non cats in windy coastal Maine on 25' flues. That being said I will probably get some key dampers in the future. My wife is not as skilled at turning the stoves down early.

 

[wagdog]

This is right. Took a year but I don't start messing with much til the IR gun reads over 800. The temp gauge reading 750 I'll just walk away.

Do you know what the internal flue temp is when you’re seeing those temps on the stove top?

As I mentioned, I’m not as worried about the stove being run hard as I am about seeing excessive temps in the flue.

If you turn the stove down earlier in the burn you will have less robust secondary combustion. This is how I control both of my non cats in windy coastal Maine on 25' flues. That being said I will probably get some key dampers in the future. My wife is not as skilled at turning the stoves down early.

Thanks for that. I too find that timing definitely plays into it.

I’ve also found that placing the wood more to the rear of the firebox box helps. Also, placing the wood in E/W (i.e. parallel to the back wall) makes for a less robust fire, especially when placed to the rear.