Resurected Timberline possible secondary??

[jbakerinc]

I have had enough with oil prices so I've decided to resurrect the old Timberline in my house. Chimney inspector friend came said I need a liner so I purchased a flexking pro with insulation to run line the chimney. Ive been reading on how to make the old girl more efficient so i have a few questions.
The perivious owner had some water pipes in the side of the stove and some type of baffle. I have seen flat baffles but this appears to have a good 45 degree rake upward rear to front.

Are these tubes acceptable for the secondary burn holes or do they need reconfigured?

Is my baffle too angled to be effective?

I purchased some firebrick and lined the top of the baffle to insulate the firebox more.

i was thinking of running some preheating pipes around the back and into the ports in the side. How important is the actual secondary burn hole size within the tube itself?

thanks in advance for your assistance and advise.





The more I look at the above pic. Do you think the larger rectangle portions filled with water at one time? If so could I add secondary air holes to the rectangle portions?

 

[jbakerinc]

anyone?

 

[begreen]

Hard to be sure, but it looks like it might have had a homebrew water-filled heat exchanger added at one time.

 

[jbakerinc]

yeah. I poked around with it last night. It is deff a heat exchange for hot water.

Best to drill holes in that or remove and reroute for secondary burn?

 

[begreen]

It won't hurt to try it before removing though the air would be added only at the rear of the firebox. Is there a baffle above this exchanger?

 

[jbakerinc]

I guess my "baffle" description could be substituted for the exchanger in this case. they are one in the same. I bought firebrick and layed them across the top of this exchange

I could add a piece of stock metal to the front of the exchanger by bolting something to the front tube I guess. moving it forward a little

 

[begreen]

Ah, ok. It's hard to orient oneself looking at the image. It sounds like the exchanger is horizontal across the top of the stove. If so, unless the exchanger us somewhat sealed at the side edges and back flames will take the shortest path, which may be behind the exchanger if there's a gap there. If it is pretty tight around the edges then yes, it's acting as a baffle too.

 

[jbakerinc]

Well you can see in the second pic where the water used to go in and out. the tubes of the exchanger are not level. the exchanger is angled up from back to front. I was thinking about drilling holes in the exchanger toward the front(higher) tube but dont want the flames to loop around up the pipe.

 

[begreen]

Flame should never enter the secondary tubes or manifold. There should be negative pressure in the stove created by draft and reduced primary air supply. This sucks air out of the secondary tubes.

 

[Mr4btTahoe]

I've been toying with my own secondary air mod for a the last couple of weeks...

From the looks of things, you could certainly use the heat exchanger for a secondary air supply... but some mods will be needed. First off, you are gonna need to keep the heat in the box... at it stands, the heat will pass through the gaps between the rectangle tubes. If you can, stack firebrick on top of the heat exchanger and then some 1/2" ceramic insulation. That will force the air (heat) to wrap around the front of the baffle instead of passing through it.

Drill the rectangle tubes along their length in the center.

You may end up needing to line the sides of the box with firebrick as well but only time will tell (that is if its not already).

That heat exchanger, in theory, should work really well for your intended application. Only one way to find out.

 

[jbakerinc]

I agree. The exhanger is solid and there are not holes between the rectangles. air/smoke is forced to wrap around the front of the exchanger.

How many holes will need to be drill? how big of bit? I guess these are some things I dont quite understand yet. Im sure air and tube volume have something to do with the equation.

I have stacked 6 fire bricks on top of the exchanger lining the top so that part is set.

Fired up this beast last Saturday after I installed my stainless liner and boy does it produce some heat too bad the stove is in my kitchen. I think i might need to crack a window to make it not feel like a sauna.

I might have to see if I can take the exchanger out at some point. I pulled a real bonehead move and forgot i cant get my arm up the pipe now to install my damper. Do I really need a damper?

 

[Mr4btTahoe]

Most I've talked to don't use one with secondaries as a strong draft is required to make them function.

As far as holes... I sized mine at 1/8" and I figured the area of the secondary inlet and drilled holes to match. That's what most do... Match the area of your drilled holes to the area of the inlets.

You'll also want a way to shut down the secondary inlets if the need arises.

 

[jbakerinc]

The inlets are currently capped at the moment so I figured I would just unscrew the lower/rear cap for testing then configure some type of valve that is easily turned on and off.

I honestly think it might work but like you say only one way to find out......

Needless to say I was very please most of the work for secondary burn was done by the previous owner

 

[Corey]

You can try it, but there are several 'features' which will be working against you.

Judging by the picture showing the pipe outlets on the outside, the angle of that plate is pretty steep. Ideally, you'd want the top to be nearly flat or just a slight angle up at the front. This helps trap heat and when the secondary flames kick in they act like the broiler in your oven - all that heat radiates down to help bake volatile gas out of the wood and continue the secondary combustion. With a steep angle, you won't trap much heat and the 'broiler' is pointed at the front of the stove not the wood.

If you let air in directly where those pipe caps are, it will have about zero chance to heat up before going into the stove. Cold air and secondary combustion really don't go together that well. You can try to pre-warm with pipes around the stove, but they really need to be inside the firebox...and have a relatively large volume so the air spends a lot of time in the pipe and can soak up lots of heat before being injected.

Then, with the solid door, you won't really know what is going on in the stove... does it need more secondary air? ...less? are the secondaries lit or no? ...is the whole thing white hot or not even warm? , etc. If you open the door to have a look, then the secondaries go out. I used the analogy with Mr4btTahoe, but running a secondary stove is like tuning the carburetor of an engine... some work goes into getting just the right amount of air and fuel for optimal combustion. Though with solid doors, it's like tuning the carb without being able to hear the engine or feel the acceleration.

If you do go ahead, I followed the Englander NC30 hole size for my tubes... which is basically a series of 3/16 and 5/32 holes. http://www.homedepot.com/catalog/pdfImages/e3/e3dda524-8c99-482d-af74-764abbb59fef.pdf I don't think the size / layout is absolutely critical, especially if the rest of the stove isn't exactly the same. Though, when the thing lights off, it can throw out some serious heat:

https://www.hearth.com/talk/threads/burnin-orange-tonight.106714/