Am I getting TOO much draft now? Jotul F3CB

[tutu_sue]

Okay, we followed Elk's advice and thoroughly inspected and cleaned our stove top to bottom, blew out ash from baffle before firing up last week. Nothing warped or cracked. Checked gaskets and replaced the door gasket. Found one bolt loose on the stovepipe adaptor which is rear vented. Went to tighten and the bolt broke. Replaced with new and applied a bead of cement where the adaptor meets the stove opening. Then we removed the top and applied dabs of cement at each corner to fill in voids and hairline cracks in factory cement. Put top back on making sure square and level and tightened screws.

Compared to last year, the usual load is burning off much sooner and flames are moving much faster and are way more turbulent than before with air turned all the way down. Don't seem to be getting as much heat out of her. This was same on 20F day and 50F day. Could it be that we have a lot more draft since sealing the stove pipe adaptor? Checked for air leaks by looking for shiny black spots around door and top and found none. Door glass is super clean where we used to get a little brown in the bottom corners. Maybe something else to check? Do you think a damper is in order?

Whaddya think?

Details: rear vented Jotul F3CB, 4 feet double wall stove pipe, 45 elbow, through wall to Class A tee and 19 ft. of Class A outside wall. Burning red oak split and seasoned for 1.5 years.

 

[begreen]

Yes, I would guess you would benefit from a damper. We had one with 3 ft. less pipe. But tell me, did you remove the top of the stove when you did the gaskets and cleaning? If yes, see this thread:

https://www.hearth.com/econtent/index.php/forums/viewthread/46/

 

[tutu_sue]

Yes sir, we sure did. I remembered your post .

 

[BrotherBart]

It sounds like you would benefit from an inline damper. I know I had to put one in the pipe for my F3 here in the basement office. My setup is four feet of single wall to a ninety into three feet of horizontal and then 28 feet straight up. If I don't use the stack damper the little dude darn near sucks small splits up the flue. And burn time for a load is about an hour.

 

[wahoowad]

How quickly is your load burning off, and try to describe "burned off." I had some concerns this weekend with uor cold blast and kept good notes on burn times and when I reloaded. It made me wonder at what point others reloaded in terms of temps and/or coal depth. I found I was reloading around 300 degrees, moderate coals left, and getting 3 hours between loads. This is with the 3CB. I was noticing increased flame sometimes, even with the front air control "shut." Other times I was getting good lazy reburn. Overall, like you, I'm thinking I am having slightly more fanning of my flames and it has had me wondering.

I could burn it all night (11 PM - 6 AM) and still have coals 6 hours later, but my temps were low and the family room had started to cool more than I cared.

 

[tutu_sue]

By burned off I mean no more flames and just embers left. This is after say 1 hour and an 1.25 hours and reloading after 2 to 2.5 hours. Used to be closer to 2 hours of flames and reloading between 3.5 to 4 hours.

I have a wireless weather station and I put one of the sensors about 4 feet from the stove and I reload based on room temp rather than stove temp since I'm upstairs most of the time.

 

[wahoowad]

Reburn doesn't happen the full 3 hours for me. Here is a typical oak burn cycle for me starting at reload:

15-30 minutes char the logs and jump up stove temp (~550);
1-1.5 hours reburn (~550-600);
1-1.5 hours significant coal heat output (500 dropping to 300);

Any chance your wood is dryer this year than last?

 

[tutu_sue]

I don't think so as most of the wood we burned last year was on 16+ months seasoning.

 

[elkimmeg]

If you inlet air passages probably improved introducing more air when the ash was removed.That would explain a heftier fire Replacing leaking gaskets would
in effect tame a fire. I am wondering as I have not taken off the Jotul top, it it is not cemented and sealed nI know on the VC ones I removed ,I have to scrape out the entire old refractory
and replace with new and not just the cornors Once the refactory bond is broken the entire joint has to be re done. Im' wondering if you now have a air leak at the top or by clearing the air passages you have more air for the burn. Others here have provided their solution of installing an inline damper

Let the stove cool down and in total darkness from inside the fire box, aim a strong flashlight at the top and rotate the strong light beam around the top seam area.
If you see no light leaks then your top seal is probably ok. Look into an inline damper installation to help control draft.

 

[tutu_sue]

Hiya Elk, thank you for your input. The lid has a fiberglass gasket around the perimeter. The top of the stove has cement in the four corners holding the panels together. We did our best to make sure we put it on correctly, but will follow your test with the flashlight today as it's very warm today and I decided not to fire up.

Now I've been looking at the Duravent double wall damper since we have that brand stove pipe and they have a stove adapter with the damper built into it. Would this be the one to get?

6" DVL Stove Adaptor with Damper
This Stove Adaptor with damper connects DuraVent's Double-Wall Black Stovepipe to the flue outlet of the appliance. The overall height of the adaptor is 4 3/4". When the male end is properly seated into the flue outlet, 4" of actual connector length will remain. The crimped end that fits in the stove is 5 5/8" at the smallest end and expands out to 5 15/16". Measure the outlet on your stove to be sure it is not to large for this adaptor.

Also see drawing I attached.

Thanks.

 

[MountainStoveGuy]

yes, thats the only real option for dampers in duravent, regular dampers arent long enough to go through the pipe. #8679

 

[begreen]

Yes sir, we sure did. I remembered your post .

OK, just checking, this had a familiar ring. How is the fire burning? Evenly from left to right? If you move the stovetop thermometer from the left to the right side (or vice versa) are the temps the same?



The duravent collar you pictured is the same one I put on the Castine last month. Note that this attaches directly to the stove. Right now, is there already a connector piece in between the stove and the 90 elbow? If yes, it may be a direct replacement. If the elbow is directly connected to the stove, there may need to be some accomodation for the connector length.

 

[tutu_sue]

It looks like it's burning evenly, flames are moving the same on left and right. Will try to measure temps on both side though. Also plan to look at the underside of the lid to check for possible leaks. Looks like shiny black spots form on the lid when it's not on right.

 

[begreen]

Also look carefully at the surfaces below the lid (top of firebox). If all is well, everything will be an ashen, grey-brown color. If there is a blackish carboned up area, there is air leaking in around that location.

 

[tutu_sue]

Guys, thank you all so much for your guidance, I appreciate it so much.

I took a really bright flashlight and I was able to reach it in above the firebox and shine it all around. I didn't see any light peeking from under the lid all sides. Next, I took the light and shone it up there and inspected the lid and top of firebox and it was all evenly colored and coated with gray ash with some bigger bits dotted here and there but no black looking areas.

I lit her up and on the second load, I set the air to it's final second and waited for the tings and pings of the warming metal to stop and measured temps on both sides with thermo. I got the same temp (490F) on both sides waiting a couple of mins after switching to let the thermo react.

We should be getting that damper this week.