FPX Burn Times

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Maverick-

I put my thermometer on the door just under the cat damper lever. No it is not accurate in terms of flue temp but it is accurate as far as door temp. So basically use it as a gauge all things relative.

I found that the door stays between 250F and 325F where 325 is a good hot burn.
 
mdfireguy, I googled backpuffing and understand what you are taliking about now. There is a lot of good information that pops up when you google it. I do not ever experience this but my wood supply is not seasoned real well and it appears that extremely dry wood can be one cause of this. It may also indicate a problem with the air flow inside of the stove. Read the article written by the nuclear reactor guy that describes how the incoming falling air can be misguided to interfere with the rising exhaust air from the fire causing the incoming air to go directly to the cat and deprive the fire of fresh oxygen. Is it possible this is happening in your box?

Maverick, I experience similar temps to Burner73. I agree that the stove top thermometer placed on the front of the door does not give you the same reading as it would if it were on the flu. However, once you get used to it, it does still tell you what is going on. Unfortunatley, the design of these units really doesn't leave us another location to put this thermometer.
 
Derek said:
mdfireguy, I googled backpuffing and understand what you are taliking about now. There is a lot of good information that pops up when you google it. I do not ever experience this but my wood supply is not seasoned real well and it appears that extremely dry wood can be one cause of this. It may also indicate a problem with the air flow inside of the stove. Read the article written by the nuclear reactor guy that describes how the incoming falling air can be misguided to interfere with the rising exhaust air from the fire causing the incoming air to go directly to the cat and deprive the fire of fresh oxygen. Is it possible this is happening in your box?

Maverick, I experience similar temps to Burner73. I agree that the stove top thermometer placed on the front of the door does not give you the same reading as it would if it were on the flu. However, once you get used to it, it does still tell you what is going on. Unfortunatley, the design of these units really doesn't leave us another location to put this thermometer.

This was very helpful. Im thinking of putting the grate back in. Maybe this will pull air to the bottom of the fire and stop the mini explosions. I read in this forum to get rid of the grate.
 
I did get rid of my grate and prefer being able to load the extra volume. However, I usually set my load on coals (hot or cold) which raises the wood enough to allow air to flow underneath. It would certainly be worth a try to see if that would eliminate the problem. Good luck!
 
hughmyster said:
Derek said:
hughmyster, I don't have any trouble with "backpuffing" at all. I do however always open the air control and damper all the way before opening the doors. I also open the doors slowly. The only time I have ever had smoke roll back into the house is when the doors were opened quickly. The movement of the doors creates a draft stronger than the draft from the chimney for a brief second allowing the smoke to roll out of the box. I really don't think drilling holes in the plate is going to help much with this matter. And the downside would be that you would lose the ability to choke down the fire for a long burn or to get it back under control if it started to climb to extremely hight temps. I could be wrong but I would strongly advise against that plan. It is my understanding that backpuffing with a hot stove would almost have to be caused by negative pressure in the house (assujing the chimney isnt' clogged). Try opening the window closest to the insert for a minute before you open the doors and see if that solves the problem. In new construction homes that are built air tight it doesn't take much to cause negative pressure. Exhaust vents like the ones above your oven and in the bathrooms are enough to create this negative pressure situation.

I also open the doors slowly when reloading. When i say backpuffing i mean when i close the air control all the way down the wood gasifies and have mini explosions causing smoke to be pushed out the door seals. My chimney is 30 feet tall. The smaller the splits the more backpuffing i get. Does anyone else see this?

Try removing the CAT and cleaning it as well as the "box" it sits in. I have a 36 & had the exact problem you described earlier this season & after a good cleaning it has been fine. Sometimes fly ash is easy to see on the CAT but in my case it was deeper in the honeycomb & not real noticeable until removed, it doesn't take much blockage to disrupt your air flow....I'd say mine was maybe 10% blocked at the most.
Also I mention cleaning the "box", more specifically once the cat is removed you'll notice a channel on the bottom right & left sides of the box, mine was filled with ash as well thus further resticting air flow. I think what was happening in my case (and probably in yours as well) is that during the mini "explosions" the gases in the firebox expand rapidly & were being pushed out the seals due to the restricted flow through & behind the CAT....through being the fly ash in the CAT itself & behind being the channels I described. When you remove the CAT you'll see there's a steel plate behind it that is not quite as wide as the box itself so the gasses must flow around the sides & also through the two channels.

Anyway try the above & see if it solves the problem...........this is my 5th season with this unit & although I clean the CAT at least once per season I had never had as much ash accumulation in the CAT as this time & really couldn't see it until I removed the CAT. Now I can turn the air down all the way, still get the mini explosions (this is normal with air cut back 100% & a good hot firebox) but no back puffing anymore.
 
woodadict said:
hughmyster said:
Derek said:
hughmyster, I don't have any trouble with "backpuffing" at all. I do however always open the air control and damper all the way before opening the doors. I also open the doors slowly. The only time I have ever had smoke roll back into the house is when the doors were opened quickly. The movement of the doors creates a draft stronger than the draft from the chimney for a brief second allowing the smoke to roll out of the box. I really don't think drilling holes in the plate is going to help much with this matter. And the downside would be that you would lose the ability to choke down the fire for a long burn or to get it back under control if it started to climb to extremely hight temps. I could be wrong but I would strongly advise against that plan. It is my understanding that backpuffing with a hot stove would almost have to be caused by negative pressure in the house (assujing the chimney isnt' clogged). Try opening the window closest to the insert for a minute before you open the doors and see if that solves the problem. In new construction homes that are built air tight it doesn't take much to cause negative pressure. Exhaust vents like the ones above your oven and in the bathrooms are enough to create this negative pressure situation.

I also open the doors slowly when reloading. When i say backpuffing i mean when i close the air control all the way down the wood gasifies and have mini explosions causing smoke to be pushed out the door seals. My chimney is 30 feet tall. The smaller the splits the more backpuffing i get. Does anyone else see this?

Try removing the CAT and cleaning it as well as the "box" it sits in. I have a 36 & had the exact problem you described earlier this season & after a good cleaning it has been fine. Sometimes fly ash is easy to see on the CAT but in my case it was deeper in the honeycomb & not real noticeable until removed, it doesn't take much blockage to disrupt your air flow....I'd say mine was maybe 10% blocked at the most.
Also I mention cleaning the "box", more specifically once the cat is removed you'll notice a channel on the bottom right & left sides of the box, mine was filled with ash as well thus further resticting air flow. I think what was happening in my case (and probably in yours as well) is that during the mini "explosions" the gases in the firebox expand rapidly & were being pushed out the seals due to the restricted flow through & behind the CAT....through being the fly ash in the CAT itself & behind being the channels I described. When you remove the CAT you'll see there's a steel plate behind it that is not quite as wide as the box itself so the gasses must flow around the sides & also through the two channels.

Anyway try the above & see if it solves the problem...........this is my 5th season with this unit & although I clean the CAT at least once per season I had never had as much ash accumulation in the CAT as this time & really couldn't see it until I removed the CAT. Now I can turn the air down all the way, still get the mini explosions (this is normal with air cut back 100% & a good hot firebox) but no back puffing anymore.

My unit was installed wrong. I cleaned the unit like you said and looked up the liner and found that right above the unit the chimney pipe is slightly open. I was drawing air from there and not through the firebox. I have pople coming out to look at this tommorow. I stopped using this as this is a potential fire hazzard.
 
hughmyster said:
woodadict said:
hughmyster said:
Derek said:
hughmyster, I don't have any trouble with "backpuffing" at all. I do however always open the air control and damper all the way before opening the doors. I also open the doors slowly. The only time I have ever had smoke roll back into the house is when the doors were opened quickly. The movement of the doors creates a draft stronger than the draft from the chimney for a brief second allowing the smoke to roll out of the box. I really don't think drilling holes in the plate is going to help much with this matter. And the downside would be that you would lose the ability to choke down the fire for a long burn or to get it back under control if it started to climb to extremely hight temps. I could be wrong but I would strongly advise against that plan. It is my understanding that backpuffing with a hot stove would almost have to be caused by negative pressure in the house (assujing the chimney isnt' clogged). Try opening the window closest to the insert for a minute before you open the doors and see if that solves the problem. In new construction homes that are built air tight it doesn't take much to cause negative pressure. Exhaust vents like the ones above your oven and in the bathrooms are enough to create this negative pressure situation.

I also open the doors slowly when reloading. When i say backpuffing i mean when i close the air control all the way down the wood gasifies and have mini explosions causing smoke to be pushed out the door seals. My chimney is 30 feet tall. The smaller the splits the more backpuffing i get. Does anyone else see this?

Try removing the CAT and cleaning it as well as the "box" it sits in. I have a 36 & had the exact problem you described earlier this season & after a good cleaning it has been fine. Sometimes fly ash is easy to see on the CAT but in my case it was deeper in the honeycomb & not real noticeable until removed, it doesn't take much blockage to disrupt your air flow....I'd say mine was maybe 10% blocked at the most.
Also I mention cleaning the "box", more specifically once the cat is removed you'll notice a channel on the bottom right & left sides of the box, mine was filled with ash as well thus further resticting air flow. I think what was happening in my case (and probably in yours as well) is that during the mini "explosions" the gases in the firebox expand rapidly & were being pushed out the seals due to the restricted flow through & behind the CAT....through being the fly ash in the CAT itself & behind being the channels I described. When you remove the CAT you'll see there's a steel plate behind it that is not quite as wide as the box itself so the gasses must flow around the sides & also through the two channels.

Anyway try the above & see if it solves the problem...........this is my 5th season with this unit & although I clean the CAT at least once per season I had never had as much ash accumulation in the CAT as this time & really couldn't see it until I removed the CAT. Now I can turn the air down all the way, still get the mini explosions (this is normal with air cut back 100% & a good hot firebox) but no back puffing anymore.

My unit was installed wrong. I cleaned the unit like you said and looked up the liner and found that right above the unit the chimney pipe is slightly open. I was drawing air from there and not through the firebox. I have pople coming out to look at this tommorow. I stopped using this as this is a potential fire hazzard.

Yikes - that's scary & a good thing you discovered it! Hope they can fix it without tearing out too much of the finish work.
 
Thats a mess... Its a lot easier for me. Whenever I go to load the stove up I have to do the same.... sort of... I have to pick the cat up and move him away from the fireplace doors.

seriously though, glad my fpx33 is a non-cat stove...
 
At least you only have to lift a cat, I have to lift a 75LB Lab :) Seriously though, his problem is not a Cat / Non Cat thing it's an instalation mistake.
 
I've been getting good overnight burn cycles so far. Been using the unit for a few weeks now.

I'll go to bed with a good fire well before 10 PM and get up at 6 with no blower going, but still a good bed of coals that easily ignites another load of wood and a very comfortable house. If I crank the 44 pretty good before we go to bed it will certainly warm the house (4,100 ft) and it will still be @69 or so in the morning and the HVAC isn't running at all. This is with ambient temps in the 30's at night with a low in the AM in the high 20's. I do have a well-insulated home.

I do not close the air all the way down just as everyone else is saying. But I'll try the method Derek has found successful as I do get dirty glass in the AM.

I burn 24" hickory logs slit @6-9 in. with a bit of smaller OAK mixed in as well. This thing throws out some BTU's, I tell ya. Family room with 25' ceiling must easily be 80.
 
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