New Zero clearance...issues???

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Jeepmanblair

New Member
Feb 9, 2021
4
Canada
Hello,

I've wanted a wood burner for years but never had the room. Having some extra time this past year i put the work in and made it happen. I moved my hot water tank to an outside wall and moved my furnace over. This gave me room in my utility room to put a zero clearance in that faces my rec room and utilizes the chase for where the water tank chimney used to be. Still being a tight spot I required a unit which didn't have a huge clearance requirements. I ended up with a Valcourt FP12 II Mundo (meets new EPA) as they have a chase reduction kit that really tightens up the clearances. It's a 2.5ft^3 firebox. The chimney is 23' of 6" Selkirk Ultimate One. I'm in Thunder Bay, ON, Canada and the temps this time of year can be into the -40 C/F range.

I have a sauna that i built a air-tight stove for. I have a magnetic flue temp gauge that I use to keep it in the 300-500f range. It's easy and works really well. I have zero experience burning in a high efficiency style fireplace. I've read and watched and learned a bunch over the last couple weeks. I've been building the top-down style fires. I get it ripping pretty good to get the secondaries going then dial it back to fully off. Sometimes the secondaries go full blow torch mode and that stove gets HOT. I've found some posts that mention red hot secondaries are normal and i would assume it is considering their location. I'm wondering if the super cold temps and the warm indoor chimney are drawing too much and even though i'm fully damped off it's pulling too much through the secondaries.

What about burn time... A full load of dry birch is basically gone in 4 hrs. Many times i'm stoked at 11:30 and when i get up and 6:00am the chimney isn't even warm. Could excessive draw be the culprit?

Another question is there's no indication of how hot is too hot. All the stove guys have some stove pipe to measure off. What's the method used to make sure i'm not overfiring my new fireplace??? Can i drill into my chimney and insert a probe?

I haven't had much luck with my vendor as we are in a lock-down right now and they are running with reduced staff.

Any help you may be able to give would be greatly appreciated.
 

moresnow

Minister of Fire
Jan 13, 2015
1,848
Iowa
Welcome to Hearth.

I get it ripping pretty good to get the secondaries going then dial it back to fully off.

Try dialing it back much, much earlier to maintain control and lengthen your burn cycle. Make a significant change in operation and work your way into a routine that works. My 2 cents worth. Assuming your burning a softwood mix?
On a side note, any chance you know Joey Imhoff?
Gotta be cold right now up there. Great part of the world!
 

john26

Minister of Fire
Oct 27, 2008
636
Wildwood MO
Is this a basement install? How tall is your chimney?
 

Jeepmanblair

New Member
Feb 9, 2021
4
Canada
I think I'm dialing it back as early as I can so it will maintain. Are you suggesting that if it gets going too much before I dial it back it just runs out of control the entire burn cycle?

The problem I'm having is the fact that I don't know what out of control is. I really want to get a thermometer on this thing somewhere.

It is a basement install with 23 ft of insulated chimney.
 

john26

Minister of Fire
Oct 27, 2008
636
Wildwood MO
Could be excessive draft you might want to check it or have some one check it for you. You might want to get an IR thermometer and check the temp above the door a magnet thermometer would tough to get a good reading on this unit.
 

moresnow

Minister of Fire
Jan 13, 2015
1,848
Iowa
I think I'm dialing it back as early as I can so it will maintain. Are you suggesting that if it gets going too much before I dial it back it just runs out of control the entire burn cycle?

The problem I'm having is the fact that I don't know what out of control is. I really want to get a thermometer on this thing somewhere.

It is a basement install with 23 ft of insulated chimney.

Can you get a nice lazy flame burn that shows intermittent secondary action, and is not in jeopardy of snuffing the fire out? Some have benefitted from reducing primary air prior to what they had been, to squeeze some burn time and heat from each load. Something to experiment with is all I am saying!
 

Jeepmanblair

New Member
Feb 9, 2021
4
Canada
I got out the IR gun. The most I saw was 520f just over the door. It settled to around 450f. I didn't do a good enough job of measuring over time to calc burn time.

I can get intermittent secondary action but it doesn't seem to last too long.

With a fresh load, when it is drawing hard, in I can hear a whistling noise coming from the fireplace. It's hard to discern whether it is the door leaking or if it's the air coming out of the secondaries.
 

john26

Minister of Fire
Oct 27, 2008
636
Wildwood MO
I would expect higher stove temps if you had an air leak or overdraft issue however it would be a good Idea to check the door gaskets with a dollar bill. I am chasing a similar issue on a Lopi insert I did replace door and window gaskets it helped some but I am sure my problem is overdraft. I would assume you are loading this fireplace east west? How full are you packing the firebox? I do not have experience burning birch I mostly burn oak, ash and locust. I have burnt some maple just to get rid of it in the shoulder season and had similar experience with that to what you are describing.
 

Jeepmanblair

New Member
Feb 9, 2021
4
Canada
I adjusted the door so the door gasket is very tight. The glass gasket is very unique on this stove. The hardware that holds the glass doesnt really put any pressure the gasket. I can slip a paper in-between pretty easy. You can see in the manual that the gasket is on the face of the glass on the top & bottom (scratch protection from trim piece) and on the back of the glass on the sides. This creates fairly large "holes" in the corners. There is a very wide gasket on the door frame that isn't shown that the side glass gaskets go on top of. I really want to remove the side glass gaskets and run a bead of high temp silicone over the wide one, dealing it perfectly. The outer perimeter of the door is outside the door seal so it doesn't get super hot.

That being said, even it the door & glass are perfectly sealed there's nothing to prevent excessive draw from pulling too much air through the secondaries.

I wish there was a 'damper' on the secondary air...at least to experment with.

Screenshot_20210212-105531_1b.png Screenshot_20210212-105423_1b.png

I'm not playing tetris and jamming the firebox full. 6 or 7 splits east/west.

I have a draft gauge for my furnace. How would I check draft on this unit? Can I drill a hole in the chimney?

John, how long is your chimney? Is it warm?
 

moresnow

Minister of Fire
Jan 13, 2015
1,848
Iowa
Unsealed door glass? That's a new one! Modern engineering at it's finest? Have you spoken with your dealer about this condition? Best of luck.
 

john26

Minister of Fire
Oct 27, 2008
636
Wildwood MO
my chimney is 29'3" I don't really have a way to check flue temps but after 8 hours the fire box is warm not hot but I am able to restart the fire after raking the coals. I did choke down my secondary it did extend burn time but I did not like the overall results it basically tirned it into a smoke dragon lots of creosote on the glass. My next step is to fabricate an internal flue damper.
 

Caw

Minister of Fire
May 26, 2020
1,021
Massachusetts
I had a leak in my glass seal once. The door seal was fine but I think I was over ambitious and jostled the glass seal out of position when I took the door off to clean it. I could hear the howling of the air at the front of the stove (usually its just the sides from the secondary tubes drawing air) and I was having trouble dialing back burns. I confirmed it with a match test...just light a match and move it along all the seals. You'll find even a small leak quickly. I just replaced the glass seal and it worked like new.

I was really new at the time and paranoid about the glass and was trying to scrub off some etching. Needless to say I learned my lesson and stick to ash/newspaper or a hot fire now. Works like a charm.