Direct / Indirect Exhaust Diverter

How will you know if it has improved anything?

Yeah it's a tough call. Those plates also blocked some radiant heat between the coal bed and firebox roof. I can still put the front baffle plate back in to see if it has any impact.

She's fired back up. Gotta steady her out and see what happens.

Lightning wrote: Gotta steady her out and see what happens.

Just speak calmly and don't startle her. We don't want a runaway.

Interesting concept for a Coal flue. The heat isnt great above the Baro usually ( 160-190?) . I will be curious how this affects the draft. Hot air needs to "eventually" rise, but this is quite a detour. How was the draft before? Very nice build, hope it works out well.., Good luck!

lsayre wrote:How will you know if it has improved anything?

I can compare over the load door with stack temps and watch the warm air duct temp. Also I can see if it will keep the house up to temp at lower combustion air settings. I'll be able to notice if it's performing a little better or not quite as well. I don't expect a huge advantage but I should be able to see some.

Before I can compare anything I need to get my fire back to normal which will take a shake and load or two.

I'm expecting better heat transfer efficiency later in the burn of a moderate fire since the baffles won't be blocking radiant heat to the firebox roof.

I just added my final layer of coal. Here is a pic of it mounted, door is open. It's a hair off square because that darn combustion blower inlet was in the way after I had already mounted one side of it. Can't move drilled holes lol. Even so it won't impede it's purpose..

Looks good. Nice work Lee!

Formulabruce wrote:Interesting concept for a Coal flue. The heat isnt great above the Baro usually ( 160-190?) . I will be curious how this affects the draft. Hot air needs to "eventually" rise, but this is quite a detour. How was the draft before? Very nice build, hope it works out well.., Good luck!

That reminds me. I need to relocate my mano probe to the firebox so I can see the effect on the negative pressure when I close the diverter door..

Preliminary results this morning look promising. I'm seeing a bigger spread between stove and flue pipe temps..

Lightning, it appears that both you and KingCoal are on the right track for raising efficiency.

Yes, it's all good. But, it has all been already proven many, many years ago.

Thanks for the kind words fellas.. another thing I am noticing is the temp variance of the flue pipe between convection blower cycles. Before, when the convection blower would come on I would see the flue pipe temp fall at least 2 degrees, sometimes 4. Now I see it fall 6 degrees every time.

Does this imply that the convection air is soaking up more heat before the flue gas exhaust can exit?

lsayre wrote:Looks good. Nice work Lee!

Throughout the installation I had some hurdles. One of them being, keeping the unit in place while I bolted it on. I also made two extra trips to the hardware store. Once for longer bolts, the other for a new drill bit. I really did have a couple WTF am I doing moments.. Hopefully the effort wasn't in vein. So far, readings are pointing to it being at least a little better than just the baffle plates. The real test is yet to come when I have some serious heat demand..

I'd like to share the circumstances for my temp readings before you guys assume they are terrible I attempt to get the fairest numbers. Comparisons can look better or worse just based on location and circumstances of the readings. Keep in mind that fly ash accumulation along the pipe wall can skew readings too. When I had the flue pipe apart, I tapped the pipe and freed any fly ash that had gathered in the pipe since firing up in October. On the flue, I read about 12 -16 inches after the breech on top of the pipe. I also cover the probe with insulation and foil tape so the pipe isn't loosing heat to the room at that particular location (which would sway the reading lower). This is where the pipe is hottest. On the furnace, the reading is at the top of the fire box, where its a more accurate temp of the coal exhaust instead of heat being radiated by the coal bed, (if it were strapped to the side adjacent to the firebricks). This makes the reading sway low, but I feel its a fairer representation of heat output overall. With all that said, here are some pics of the arrangement.
These readings are with a fire 12 hours into the burn cycle. They have been steady since I got up this morning, about 3 hours ago.

SO, with a combustion air setting of the pointer at 9 inches from the floor (spinner is always closed) and secondary air at only 10% I would normally (with the baffle plates) get about the same over the load door temp (in the 220's) but I would see a higher flue pipe temp in the 170's. Here, with the diverter installed, I'm getting 153 on the pipe that dips down to 147 during a blower cycle. I think this proves that the exhaust is giving up more heat before exiting than with the baffle plates. This combustion air setting is a low slow burn. There is no visible red glow observed at the top of the coal bed. Its 31 degrees outside and 72 in the living room.

You may have noticed the temp gauge under the load door. Currently its close to what over the load door is reading. When I rev up the fire, the gauge under the load door will shoot up to as high as 500 degrees, depending on conditions in the coal bed (sometimes ash accumulates there keeping it lower) while over the load door reads 325-350.

And yes, that is a ladybug crawling along the corner of the computer desk.. She musta come outta the wood work when we had that warm day on Monday..

you will want to get your draw rod set up soon. what's going to happen is you're going to start having a combustion chamber full of exhaust gas slowly rolling over and dropping to the lower exit.

because of that you will wan to be able to open the upper hatch for a while before you open the load door, or, just turn on your draft inducer and basically vacuum it out.

either way I think you'll see a measurable and useful improvement.