smoke from top of Bob Fisher Insert

[mikeU]

I am new here, so good morning from Maryland. We have lived in our home for over 10 years. We have a Bob Fisher insert (built September 9th, 1981) in the basement that we never used. The previous owners said that they loved it, but I was worried about firing it up due to young kids. I had it inspected, cleaned, minor pointing, and a new stainless steel cap put on. The insert was "pulled" and the damper removed from the chimney, which extends 3-4 feet above the roof peek.
Last night was in the 30's, with no wind. Opened the Fisher damper, opened the vent, loaded with kindling, heated the damper exit to chimney with a bit of rolled paper and started the fire. All was well, and flames headed up the damper without problem except smoke rolled into the basement from the flashing top and air deflector. We opened windows and set up fans. It took about an hour to clear the house of smoke, and I let to logs burn down to ash.
Called the company who did the work, but wanted to find out if it was something I did/did not do.
I will try to add a few photos. Me sitting in a smoke filled room cursing at the insert. All so see side label for further info. Thanks for any help; Mike

 

[pen]

welcome to the site.

Did you notice if they put any stove pipe or a section of chimney liner attached to the stove and up into the chimney?

How recently was this cleaned and inspected? Any chance some critter could have blocked the cap?

pen

 

[mikeU]

Thanks ...no pipe was added...looked like about 3"-4" was sticking out from the back when they pulled the stove out in march 2011...clean with new cap and no animals...

 

[coaly]

No need to curse the Insert. It's the chimney, or connection to it.

First, if the Insert is just set back into the hearth, that's the way they were designed to be installed. The heat naturally rises out of the Insert outlet, past the damper if you have one in the chimney, and up the flue. As long as your damper in the fireplace is opening, and there are no obstructions, smoke and heat is going to rise out, heating the flue liner and chimney. Once hot, this is the draft that causes the air to be pulled into the Insert via the adjustable air intakes. I would slide the Insert out, and look up the chimney with mirrors and flashlights to be sure it is open all the way. Something is blocking it. Make sure the outlet on the Insert is lining up with the flue, as in maybe the fireplace is built with flue just behind the mantel, and the stove blocks it off when shoved all the way in ?? Possibly a built in smoke shelf with something on it?
The top of the insert looks like the picture below. You mention a 3 to 4" pipe out the back ?
IMPORTANT ! Once the chimney is hot and drafting, any leaks around the face seal, will not allow smoke in, it pulls air out of the house and up the chimney. (cooling the rising gasses and decreasing draft -not good) That's the reason for sealing the block off plate to the face of the hearth. Not due to smoke coming in, due to heated inside air leaking out.

To prevent removing the Insert when cleaning, most are now connected with a flexible liner that connects to the top of the insert and goes all the way up. But it's not necessary to make it work. Just makes cleaning easier.

Whatever the problem is, it's not the Insert. Heat (and smoke) rises whether there's an Insert in the hearth or not.

 

[coaly]

Your tag shows it's UL listed and made by Cesco Industries Inc. Roanoke VA. They later made the Tech IV Insert. Nothing to do with yours, just some Fisher trivia.

 

[CamFan]

Coaly you are right on the point there. The only thing I would like to add is the face seal. If it allows air to go by the flashing into the chimney it can cause problems too. You hit on it but I think it is real important for a insert with out a liner. All the air going up the chimney needs to go through the stove and the spin caps. The way you can check your insert face seal is to take a lighter or a match and go alone the edge of the flashing. Everywhere the flame pulls toward the flashing add non flamable insulation until it stops pulling between the flashing and brick on the fireplace front. This generally solves more problems of a bad burn when the draft caps are not wide open but it is important for all fires in the insert.

 

[coaly]

There, I added a bold IMPORTANT. Everything I have to say is important, you knew that. Now convince my wife. :lol:

Mike, Are you sure the smoke was from the combustion INSIDE the Insert, or did it start smoking after it heated a mouse nest or other material between the stove walls and outer shell? If this was unused in the basement that long, (10 years!) something could have taken combustible material into the air jacket above the inner liner. (firebox roof) Around the outlet is the hottest part that will certainly make anything smoke that may be in there. (tissues,acorns, shredded up paper) You should be able to see it with a flashlight, poke around with something like a plumbing snake to make sure it's clean. I've seen kids hide candy wrappers in strange places. Or someone dies who stashed cash in a not so smart place. hmmm

 

[mikeU]

Thanks for all the comments and advice. The photos from Coaly was very helpful and jarred my feeble brain to remember that there was no pipe after the back/top damper "too many meds" The insert was taken out last March, cleaned, and inspected. That was the first and last time I saw the back of the unit and into and up the chimney. I do remember some animal (?) stuff was sitting on the rear of the stove around the damper, which was vacuumed off. That work was preformed the same day the cap was put on. The terracotta lining of the chimney was totally clean and bright orange. No animals or nest on the smoke shelf. The chimney damper was removed at that time and a new cap put on top. I can see through the cap from my deck, and no sign of blockage. The chimney sweep company that did the work called me back tonight, but we were out, so I'll get back with him next week. He left the message that this could be a common problem with a common fix. I have enjoyed working with this guy (fast plug)his name is David owner of Maryland Chimney Services. The insulation around the flashing and brick seems OK and solid, but I will do as CamFan suggested and check for insulation leaks with the lighter. I did not see any smoke coming out of anyplace except from between the top of stove and the base of the air deflector. So again Coaly is correct in pointing out that this is NOT smoke from inside of the insert, but someplace beyond the damper. No smoke came out of the doors, even when closed, opened slightly, of full. With all that said, I will try to fire her up again tomorrow, but have the fans ready and windows open before I start. I will do this during the day so as to see if I can see smoke coming out of the top of the chimney, which I could not because it was too dark Friday night. I'll send results after that.
Thanks people-
Mike

 

[Redbear86]

I know this is an obvious one but some fireplaces have a built in baffle plate in the chimney, i think its to reduce draft when the fireplace is not in use mainly, i know i've started a fire without checking to make sure this baffle was open before and was smoked out for it, maybe when it was being cleaned/inspected it go closed. If one is in your chimney you should be able to see it with the insert pulled out.

 

[coaly]

That's the "fireplace damper" they removed when they had it out.

I believe the smoldering material is between the outer jacket and the primary combustion chamber. With no smoke opening doors, the chimney and insert is doing what it's supposed to do. If you get smoke in there again, leaving the doors open a bit will pull the smoke out of the room if you crack a window or door. If you have a screen, open the doors fully, and it will evacuate the air in the basement just like a fan blowing it up the chimney. (On a hot still day with no air movement, as soon as the outdoor temps are cooler than the inside of the house, you can light a small hot fire with paper or cardboard to preheat the chimney. This starts the draft, and with windows open downstairs you will feel the cool air being drawn into the hot house, exhausting the overheated house up the chimney. I have no A/C and use that technique to pull cool night air in. You don't want enough fire to start heating with the stove, that's all. Same principal to exhaust the smoke. With open burning, the screen must be used). I was referring to using a plumbing snake or piece of stiff Romex wire in the slot above the combustion chamber, below the deflector shield. And in the bottom slot (shown below) This space goes all the way around the insert, down the back and sides, across the bottom. A rodent going in the bottom, has access to the entire air space around the stove. This space is only open top and bottom to see in. When you hit nesting material, the sound will change, and you will feel it. The hottest area is on the top, right around the damper. If you can fit a piece of hose that fits in the slot, you may be able to tape it on a vacuum cleaner hose and get a hold of it piece at a time. Being shut down for 10 years is enough to allow dust to settle on it, and smoke off during the first fire. But it has a different "hot" smell that shouldn't be confused with the combustion particles from the inside of the firebox.

Below is a picture of the airspace on the bottom, where the accessory fan and ductwork blows the air out the top slot.

 

[CamFan]

If you use an air tank and compressed air you can clean that area out too but depending on what is in there is can be messy. but I would rather clean up the mess than get the smoke or smell of debris burning in the void.

 

[mikeU]

Thanks for all the comments and advice. Again, the photos from Coaly were very helpful. I think you are correct with the open spaces.
I took a small vacuum cleaner hose and cleaned all around the insert, and got the corners and vents. Truth be told, almost nothing, in the way of dust or dirt, came out. I opened a small window before I got started this time, and built a smaller fire. The fans were ready and I pre-heated the damper inside of the insert until the flame went up and out. I started the fire about 30 min. ago, and so far so good. Temp has only reached 250F. I went outside and was able to see smoke coming out of the chimney. It is rather dark gray to black on exiting. It is a very clear day and I see to turning to white puffs at about 10 feet over the exit. I’m thinking it is still burning off dust and stuff from being unused for, actually, 11 years. So we will see. Does anyone have a comment about the black/gray smoke…is this normal, or am I correct in thinking it is still burning off stuff
Thanks,
Mike
PS the temp just hit 300F and I'm starting to smell something but can't see any smoke in the house...yet

 

[mikeU]

Thanks you Mr. Coaly The fire alarm in the house went off just as I was going to the basement to check the smell (plastic). Looking over the photo Coaly sent, I got down on the floor with a flash light and looked into the side vents. One plastic toy soccer ball on the left, another small clear plastic ball on the right and a yellow/clear fish bobbin. I fashioned a hook with a metal hanger and pulled them all towards the side vents, but even with gloves it was too hot. I was also surprised that the balls, while made of hard plastic, did not even seem soft. I was hoping to grab them with some long nose pliers and squeeze them out. They are each about 1†round. Now I will let the fire burn out as I turn in my head the next move. BTW, I am too old/weak with Lyme and RA to move the stove, so worse case, I’ll have to pay someone to help extract the toys. I think this may also answer the issue of black/gray smoke coming out of the chimney
Thanks,
Mike

 

[coaly]

Removing the Insert wouldn't help removing the debris. Fishing it out is all you can do.

You probably have soot dust and debris on the smoke shelf, or dust and dirt from cleaning or dirt from the atmosphere settling on top of the Insert. It will go up the chimney and clean itself up in time.

Now as for cursing out the old Insert; When you're on your knees in front of it fishing this stuff out, would be a good time to have a long talk with it. Maybe give it a name, let it know you're sorry for taking it out on him (or her). Ignoring him (or her) for over 10 years, then being abusive during it's first fire is not a good way to start the relationship. Maybe treat it to a little Maas Metal Polish when things have cooled down between you two.

 

[Bone1099]

Im burning the very same stove right now. Except i removed my damper and directly connected my opening to the clay liner in my chimney. (it draws better than Joe Kamel)

 

[Bone1099]

Hey coaly i didnt mess up with that damper removal did i?
Sorry for the Hijack

 

[coaly]

A damper in the Insert is required for various reasons. Since every chimney drafts differently, it gives you a way to fine tune your draft, and you soon learn where it works best. A strong draft (insulated liner) may allow you to run it partially or fully closed, a weak draft may require 3/4 open. Once you know where it drafts best, you can adjust for outside air temp. Warm days with the least amount of draft, you open a little more, extreme cold days you can close it more than normal and maintain the same draft. (this is what an automatic barometric damper does) This gets the most heat out of your Insert, keeping the chimney as clean as possible. After running mine for years, thinking I had it mastered, I learned how to get the most heat out of it, and only require one seasonal cleaning. That means a lot when it's your ONLY heat source and you don't want to shut it down for service.

You can control the rate of burn by closing air intakes, but this is mearly snuffing the fire causing smoke. The damper has more control on the velocity up the stack. Slowing the fire down with the damper, then adjusting the air just enough to glow with little flame works best for me. The more heat required, the more air I give it. Since I have an insulated chimney, I only open the damper fully during start up. Within minutes I need to close it partially to control rate of burn. I think of it as putting on the brakes. The air intake is like giving it gas. You can idle along, but you're not going to stop until you hit the brake.

Without a baffle inside, you're letting more heat than necessary out. So the damper is your makeshift "baffle". It doesn't roll the smoke back into the fire, but slowing it down, and making it turn at the point of exit where the gasses are hottest is the last chance to burn any unburned particles.

When you burn down to lots of coals, 4 or 5 splits can create a 6 inch deep glowing mass, you have virtually a smokeless fire with lots of heat available. This is burning charcoal with little to no flame. You want to close the damper fully to allow that glowing mass to radiate heat into the Insert for hours. Damper closed, air intakes cracked you will achieve a much longer burn.

Page 13, under Preventive Measures suggests burning in fireplace mode with screen in place at least 5 to 10 minutes a day. Canadian manuals call for 10 to 20 minutes a day. This is to bring flue temperature up. Burning with doors open requires the damper to be slowly closed until smoke starts to roll in at top. By opening damper just enough to allow smoke to vent properly, you're getting the most heat out of the Insert in fireplace mode.

Another reason not to remove the damper is that the appliance is UL listed "as tested". The UL rating is lost since you're using it as untested. In the event of a chimney fire, you're going to want to close the damper tight, along with the air intakes. Use of a coal grate also requires damper use. They are listed for coal use in the US, not Canada. The air leakage around it, and the flat spot in the radius allows the proper outlet size for this.

 

[mikeU]

I believe this will be my last entry on my smoking Bob Fisher insert. Dave from Maryland Chimney Services came by and pulled out the stove, and took off the side wings. Out came a hard yellow toy bal a hard foosball (what I originally though was a toy soccer ball), a sort of melted daedal (toy top for spinning-timely for Hanukkah), a nickel, dime, unidentifiable piece of metal, lots of dirt and insects…after this was all vacuumed out, we took a hard look between the deflector and top of the stove. Coaly was great in his comments and pictures, which I shared with Dave, right near the pipe that runs through this sealed heat box area, was a glob of black stuff that turned out to be plastic…the source of all the smoke and stink during the last 2 firings of the stove. Dave tried to scrape it out, pull it out, and sand it out, but nada…nothing worked. We talked about using a blow torch, but neither of us had one handy. So after 2 hours of working and refusing compensation, Dave had to leave. Two nights ago I went to Home Depot (at the suggestion of Dave’s partner, an d bought a length of flat aluminum, about 3mm by 3cm, by 1 meter. I hammered one end around, and started a small fire in the corner in the back under the plastic. When the temp reached about 200, I could smell the plastic start to burn. With heavy duty gloves and my created tool, I was able to reach in and scrape/pull most of the still unidentifiable plastic out. If I rolled all of what I pulled out into a ball, it would be about the size of a small fist…who knows, maybe it was another toy ball at some point of is destructives and gaseous history. House still stinks, but we got almost all of the plastic out. Next time I set up a fire I plan on getting it nice and hot and go in for the final cleaning.
BTW Coaly, I got some metal polish, and shined Bob up…we will see if this helps a bit…
Thank you all for you comments and support.
-Mike

 

[coaly]

Good for you, and Bob. Don't forget to open the draft caps occasionally, reach through the holes in the door, and dab some hi-temp grease or antisieze on the bolt threads behind the cap. It saves the threads in the caps, and feels good to him. Those doors will spiff up nice.
Orange peels on the stove top section smell good, A couple boxes of baking soda left open may absorb some of the smell too. Can't hurt.

I had a duplex rental home plug up the sewer years ago that I couldn't open up even with my own motorized router tool like the pros use. Ended up digging down to the pipe at the foundation, across the front yard to the sidewalk, where there was a 4 foot high retainig wall that droped down to street level. Broke up two sections of sidewalk, and dug a foot or two UNDER the street until I found one of those toy Transformers caught in a root at the last elbow where it dumps into the city sewer pipe ! I kept telling myself it was all old pipe that needed to be replaced anyway.