My Ongoing Fireview Saga

[Slow1]

Getting too much air? What air setting did you set it to?

I phrased that poorly. I meant too much draft. I started at 4 and turned it down to 2.

Before putting any sort of damper in there, try taking it down below 1. I found that the control is pretty impressive on my setup and although I haven't confirmed it, I don't think it is a linear relationship - i.e. I suspect that going from 1 to 2 may more than double the air allowed through the system.

Based on my observations with coals leftover from a burn (pile up the few embers in front of the 'charcoal pieces' and increase air) putting the air up to 4 is very much akin to opening the ash drawer in my old VC - it blows air down that airwash pretty hard - I've seen ash and sparks fly back from the front of the pile. But I can then take it down to 1 or below and pretty much snuff the life out of the coals. Obviously YMMV.

 

[wendell]

I know I had too much draft on my Morso so I am a little paranoid, even though Woodstock was sure I wouldn't need one. My concern came because the flue temperature stayed below 300 with that burn and it caught my attention since I was afraid the exhaust was getting pulled out too quick.

But, I'm sure I won't know until a real burn happens.

I'm still trying to get my head wrapped around the flue temp needing to be above 500 before engaging the cat. On my Morso, the max flue temp was 450!

 

[Slow1]

Are you using a probe thermometer there for that 500 goal? Surface temp target is 250 for single wall pipe...

Also, keep in mind that the stone REALLY absorbs a lot of heat from the fire (really one of the good things). I hope someone will jump in and correct me if I"m wrong on this point too, but isn't a HIGH flue temp generally associated with too much draft?

 

[Highbeam]

I'm still trying to get my head wrapped around the flue temp needing to be above 500 before engaging the cat. On my Morso, the max flue temp was 450!

Wait a minute now, the Morso folks tried to tell you that 450 was the max flue temp or is that all you could get? I easily and intentionally run up past 800 in the flue with each fire. I expect to cruise in the 400-600 range. The pipe is built for 1000 continuous so why on earth would you be worried about temps below that?

 

[wendell]

Are you using a probe thermometer there for that 500 goal? Surface temp target is 250 for single wall pipe...

Also, keep in mind that the stone REALLY absorbs a lot of heat from the fire (really one of the good things). I hope someone will jump in and correct me if I"m wrong on this point too, but isn't a HIGH flue temp generally associated with too much draft?

It is surface but 250 degrees difference between surface and probe. That seems a little high.

You know, I've heard that too but my thought is the exhaust is moving up too fast to heat up the pipe.

I guess it's time for BrotherBart to weigh in!

 

[wendell]

I'm still trying to get my head wrapped around the flue temp needing to be above 500 before engaging the cat. On my Morso, the max flue temp was 450!

Wait a minute now, the Morso folks tried to tell you that 450 was the max flue temp or is that all you could get? I easily and intentionally run up past 800 in the flue with each fire. I expect to cruise in the 400-600 range. The pipe is built for 1000 continuous so why on earth would you be worried about temps below that?

450 8 inches above the flue collar was the recommendation for my stove. I could get it way hotter than that!

 

[Wet1]

Are you using a probe thermometer there for that 500 goal? Surface temp target is 250 for single wall pipe...

Also, keep in mind that the stone REALLY absorbs a lot of heat from the fire (really one of the good things). I hope someone will jump in and correct me if I"m wrong on this point too, but isn't a HIGH flue temp generally associated with too much draft?

It is surface but 250 degrees difference between surface and probe. That seems a little high.

You know, I've heard that too but my thought is the exhaust is moving up too fast to heat up the pipe.

The interior to exterior delta will reduce if exhaust temp is at this elevated temp for a decent amount of time, regardless of exhaust velocity... but 50% is the general rule of thumb. Obviously single vs double wall will make a huge difference as well.

 

[Wet1]

I'm still trying to get my head wrapped around the flue temp needing to be above 500 before engaging the cat. On my Morso, the max flue temp was 450!

Wait a minute now, the Morso folks tried to tell you that 450 was the max flue temp or is that all you could get? I easily and intentionally run up past 800 in the flue with each fire. I expect to cruise in the 400-600 range. The pipe is built for 1000 continuous so why on earth would you be worried about temps below that?

450 8 inches above the flue collar was the recommendation for my stove. I could get it way hotter than that!

450 at only 8" above the stove seems very low for a max flue temp.

 

[wendell]

Yes it does, that's why I have new stove! :cheese:

 

[Slow1]

Are you using a probe thermometer there for that 500 goal? Surface temp target is 250 for single wall pipe...

Also, keep in mind that the stone REALLY absorbs a lot of heat from the fire (really one of the good things). I hope someone will jump in and correct me if I"m wrong on this point too, but isn't a HIGH flue temp generally associated with too much draft?

It is surface but 250 degrees difference between surface and probe. That seems a little high.

You know, I've heard that too but my thought is the exhaust is moving up too fast to heat up the pipe.

I guess it's time for BrotherBart to weigh in!

The general 'rule of thumb' is that the surface temp is about 1/2 that of the inside. I'd love to understand the physics involved in why this is, but it seems to work out - thus Woodstock has the recommendation that you not engage the cat until you get 250 on the surface (500 is the actual cat required temp to ignite).

As to the "moving too fast up to heat the pipe" this theory would be sound IF you were doing a flash fire lasting a second or two perhaps, but since the gases are flowing up there more or less in a constant flow, the heat is present and thus the rate of flow doesn't (as far as I understand the physics) significantly affect the transmission through the pipe to the outside surface. Since there is a delay in transmission you are getting an averaging effect in any case - the slower the transmission, the greater the average (and lag if you want to think of it that way). Thus the desire of folks to use probes to get a quicker and perhaps more accurate reading of the temps.

However all of this still doesn't really answer the question of whether or not having too much draft would increase or decrease the temps in the flue. My working theory on this is that it would increase the temps during the peak burn period as it is pulling a lot more air through the stove in general and thus feeding the fire more than one desires. Then once the fire is down to coals, it would still be warmer than the 'right' amount of draft/airflow since it would pull more air over the coals (cold air in) and then hot air out of the stove and up the pipe that otherwise would stick around in the stove and heat the stove and eventually the room.

"To much draft" basically then is when you have more pull from the chimney than you can overcome with the stoves controls and thus slow the rate of air through the stove. Somewhat subjective I suppose, but a simple definition. What is optimal amount may vary from one stove design to another - I expect that in my case the FV is giving me far more control than the old stove (for whatever reasons) and I don't feel out of control anymore.. I used to feel I had too much. Of course, I'm not going to make a final decision until after a good COLD day with some wind etc... Anyway, that's my how I think of it - I could we off my rocker.

 

[Todd]

I can tell you from side by side testing that my probe thermometer roughly reads twice the temp of the woodstock stove top thermometer. Just don't jump the gun and go by the pipe temp to lite off on cold starts, give it some time to warm up the whole system or it may stall or shock the cat. Once you have a good coal bed established and you want a reload it can take less time to engage. You will get it all figured out there rookie, it takes a little trial and error.

 

[wendell]

So, would I be safe in assuming that once you are burning a real load of wood, you will be bringing the air supply down a while before you can engage the cat?

 

[Todd]

So, would I be safe in assuming that once you are burning a real load of wood, you will be bringing the air supply down a while before you can engage the cat?

Yes, when reloading with a good coal bed I find the air set at#2 or less is all I need to get it started. Then when I engage I always have it at about #1 and turn it down from there. Small air adjustments go a long way with this stove, don't think of it as #1 is a low burn and #4 is high burn. With a full load I consider a low burn .5 or less, medium .75 and high #1 or a smidge more. Anything over that for me would be a waste of heat and fuel. The cat needs time for the smoke to pass through and burn, too much air speeds up the draft and smoke will pass through and not have the time to ignite. This is why cat stoves are most efficient at the lowest burn.

 

[wendell]

That's helpful, thanks.

What I was referring to though was from a cold start. 4 to start, down to 2 when the stove pipe hits ? and then down to 1 or lower and engage the cat when the top hits 250.

Is that about right once you fill in the blank?

 

[Slow1]

That's helpful, thanks.

What I was referring to though was from a cold start. 4 to start, down to 2 when the stove pipe hits ? and then down to 1 or lower and engage the cat when the top hits 250.

Is that about right once you fill in the blank?

From my experience my fill in the blank answer would not be a temp, rather as soon as the kindling is fully engulfed. It only takes a couple minutes to get there and I find that moving down to 2 does great for getting things things going and up to temp.

 

[Todd]

That's helpful, thanks.

What I was referring to though was from a cold start. 4 to start, down to 2 when the stove pipe hits ? and then down to 1 or lower and engage the cat when the top hits 250.

Is that about right once you fill in the blank?

Yes, I try and keep my probe under 1000, so if I'm at #2 and the temp gets close to 1000 I back it off. You will see the flames with higher air setting get sucked right up the bypass into the pipe and when you reduce the air the flames will back off and swirl around inside the fire box more heating up the stove instead of the pipe.

 

[wendell]

You know it's kinda sad watching these start up fires. You get this nice little fire going and you gotta just watch it die. Well at least for tomorrow for burn #3 I'll be able to get it hot enough to engage the cat for the first time.

 

[Frostbit]

Dang. That is one freakin' gorgeous stove and install. Kudos.

 

[wendell]

Thanks but don't tell Bigg Redd! :lol:

 

[Flatbedford]

You know it's kinda sad watching these start up fires. You get this nice little fire going and you gotta just watch it die. Well at least for tomorrow for burn #3 I'll be able to get it hot enough to engage the cat for the first time.

I know how you feel. I've done three burns with my Fireview so far. the next one is gonna be a real one. It just hasn't been coll enough for that yet. I can't wait to really let it burn!

 

[wendell]

Well, did the third fire this morning but used pine (OMG, I hope I don't ruin my stove!) and again, the fire was dying quickly before the stovetop reached 250. Today is our last nice day for a while so I decided to cheat and after it was down to coals, I added 4 more small splits. I waited until the wood was all charred and the temp was now above 250 so I put the air down to 1 and engaged the cat. Nothing really seemed to happen for about 5 minutes but then the flames did change and the flue temp dropped. Just came back downstairs after running some errands and it is kind of bizarre. The wood is obviously somewhat smaller but not nearly as much as you would think and the only flames are just climbing up the left side of the stove. It seems almost like the flames and the wood are unrelated.

 

[Backwoods Savage]

They are unrelated Wendell. You know what happens sometimes when you have relation in the same small room!

 

[Todd]

Yeah, those are what they call ghostly flames, they seem to float above the top of the splits and suddenly vanish and reappear. That's what my stove does with a low burn and if you tweak the air up a little you will see the coals brighten and the flames will come down to the wood. Sometimes when you first engage it looks like the fire is dying and all of a sudden it comes to life. Your draft may act different so your air settings may be higher or lower than other Fireview owners.

 

[wendell]

Is that normal for the cat to take that long to become active? I would think, once you close the bypass that the effect would be almost immediate.

Or did I not wait long enough for those new splits to get really burning and that is what happens if you engage it too soon?

 

[Todd]

How long did you wait to engage? Might of been too soon or maybe it needed a little more air? Hard to say, it will take some trial and error. Sounds like your done with break in, I'd fill her up next time and play around with different air settings and watch the temps and flames.