Excessive Draft Options???

I have had the Harman Mark 111 in service for about a week and the am having a problem with excessive draft. An inside chimney about 35 ft tall from the stove pipe entrance. No chimney cap. Brick construction 8 x 12 tile liner. Basement installation.

Stove configuration. Stove directly to a 6” Tee with cleanout in the rear. Straight rise 28” centerline to centerline to a horizontal 6” T cleanout in front. This T is coupled to another T which is for the Barometric Damper then a 4” piece of pipe to the chimney thimble.

Takeoff for Manometer up 18” from bottom stove T.

I installed the Dwyer Model 25 yesterday and I am getting a reading in the range of .09 to .11 with a 300 degree fire. I have rezeroed it several times.

I read the instructions for my RC Barometric Damper made Nov 13, 2008 and it states in section 2.2 for a horizontal installation to add the 1 – 2 supplied washers under the back flap weight. The kit came with 4 washers and the back weight could not be removed as the rivet on the front side of the flap just spun in place. On all the posts I have read on this forum I have only seen the changing of the front adjustment screw knob from right side to left side for the change in direction on a vertical run to a horizontal run. Nothing about washers.

There was also a binding as it opened and closed. You could see the paint rubbing off both sides between the flap and the outer shell where the pins rotate.

Called Fields Controls and the Tech support guy knew nothing about adding washers but did say it was OK to file a little off the flapper plate to eliminate the rubbing.
I installed the Barometric Damper with a medium fire and set it for .06 as the fire cooled down the draft reading went up to .09. It also felt like there was a huge draft and the basement temps were dropping. Pulled it out and replaced the cap for the night. Tried the Fields RC again this morning and got the same results. Does this sound right?

What are the best options to lower and control the draft? I have been through the threads on Manual and Barometric dampers and am totally confused on what direction to go. Without the archives on this site I don’t think I would have ever gotten this thing figured out.

Wish I could post pix but the software for the camera is not compatible with windows 7 and I have not figured out a solution.

Thanks for any suggestions for getting this issue resolved.

If your camera has a removable memory card you don't need camera software to upload photos to your computer. You will need a memory card reader though to connect to your computer.

As for the baro damper, as you face the baro damper, do you have the adjustment weight on the left side and is it slid all the way to the right? Both RC dampers that I have didn't come with washers for the back flap so maybe someone else will chime in on that. You wouldn't want to add weight to the back of the flap anyway because that will pull stronger draft through the stove. Adding weight to the front top of the flap will cause less draft to be pulled from the stove.

Black*Rocks wrote:I installed the Barometric Damper with a medium fire and set it for .06 as the fire cooled down the draft reading went up to .09.

That doesn't sound right. Are you sure it's not the opposite? Draft will lower as the stove and chimney cools.

if so facto...get a SS chimney cap that covers the 8x11 and converts it to a 6" round outlet.....thus reducing the exit size

Either Add another baro or get a bigger one. To add more room air and reduces draft on the stove.

So, you are getting this high reading at a full burn and the baro is OPEN quite a bit?

I had to add a SS washer to my baro, under the supplied weight, to get enough weight to keep my draft correct. Don't recall it being supplied with the baro though.

Mine is in a horizontal setting, weight on the left side slid all the way to the right.

Poconoeagle wrote:if so facto...get a SS chimney cap that covers the 8x11 and converts it to a 6" round outlet.....thus reducing the exit size

Although this solution is often used, i'm not a huge fan, especially on an interior chimney. Instead of having a stack that is under negative pressure along almost its entire length, you end up with a stack that, during warmer weather, has significantly reduced negative pressure near the top or positive pressure thus encouraging the escape of flue gasses into the upper portions of the home. The flue will end up with a significant positive pressure area as the neutral pressure zone is lowered from the top few feet or less to somewhere far lower.

I had to put two washers under my weight, works great.
Something seems odd, as already mentioned about your draft getting
stronger when the fire went DOWN..... just make sure that the thing isn't binding up...
Also, if your draft is like 1.0, be sure the flap is opened wide, if it isn't, something isn't right..

Dan

Thanks for all the replies.

Rockwood
As for the baro damper, as you face the baro damper, do you have the adjustment weight on the left side and is it slid all the way to the right
The weight is in the left slot about mid point but has been tried at both left and rightlocations.
That doesn't sound right. Are you sure it's not the opposite? Draft will lower as the stove and chimney cools.
I am pretty sure but will recheck. That is why I am wondering about the weights – washers that were supplied with the damper. The addition of 1 – 4 washers will really affect things. I have no way to verify it is working as designed.

WNY
So, you are getting this high reading at a full burn and the baro is OPEN quite a bit?
This reading is at a 275 – 300 degree burn outside temp mid teens. No Barometric damper installed at this point. When the Barometric damper was installed it was always part way open high or low fire.

Did some checking this morning, Outside temp 18 degrees stove at 275 degrees (Magnetic thermometer) in the upper left corner front side. Draft floating at .08 to .09.
I added a 1/4” hole in the stove pipe 12” up from centerline of the stove discharge. Installed a Bacharach Draft-Rite gauge and it was the same reading as the Dwyer model 25. I know that portion is working correctly. I then inserted a Bacharach Tempoint probe thermometer which reads from 200 to 1000 degrees. The flue gas temp was 285 – 290 after stabilizing. The next test was with a Condor probe thermometer which produced a reading of 290. These probe temperatures were about the same temp as the magnetic thermometer on the front of the stove. In the same pipe location the magnetic thermometer was reading about 175 surface temp but that may be off a little due to a little creosote inside the pipe from several stress relieving wood fires.

Both of these Bacharach units were tested against professional equipment last year when the new oil furnace went in.

Did a lot of thinking last night and to me it seems that the Barometric damper is always increasing the negative pressure in the house and requiring more outside air to be brought in. This would be 24/7. Even if completely closed there is about a ¼” air slot between the damper plate and the outer ring. If the Barometric damper is completely eliminated then there will be less cold air entering the house. By controlling the air flow through the fire by reducing the coal size from nut – stove size to pea – nut size and running the spinner at 3/4 of a turn open from the closed position I was able to get a nice burn at 300 degrees through the night. Nice blue ladies were dancing. This morning the draft was at .09. Even if the chimney is pulling .10 it can only pull what it is allowed to. To me it seems that controlling the draft through stove before the fire would be good way to go. Am I crazy???

The barometric damper does one thing. It doesn't allow a change in draft to pull more air through your coal bed, thereby attempting, to the best of it's abilities, to limit your heat loss. If a more draft is created than set point on the baro, it opens to draw room air. When that draft settles down the baro closes.

Either way you're going to have a draw of fresh air into the house. The difference is whether it takes your heat out with it from the coal at 300°F or just room air at 75°F.

It's a hard concept to understand since we're so conditioned to believe that an open hole sucking heated room air should be avoided at all costs. I know it took me a very long time to understand the benefits personally.

You mentioned the baro was always part way open high or low fire. It has more to do with the draft out of your chimney than the fire you have going. A hot fire will produce a better draft...but...so will a good breeze, whether the fire is going or not. In the middle of summer my baro can be banging open and closed.

From watching my father in laws Chubby work I can tell you this. I've seen his stove sit at 350°F give or take 20° and be able to hold my hand on the flue pipe above the baro. It sits at around 100-120°F after the baro. That's what you're looking for.

Black*Rocks wrote:Even if the chimney is pulling .10 it can only pull what it is allowed to.

When the stove is hot the chimney will pull that draft no matter what. If your stove is airtight you CAN control the volume of draft being pulled through it but the pressure pulling on the stove WON'T change. A baro damper simply gives an easier path for the chimney to pull from resulting in a consistent pressure being applied to the stove.

Black*Rocks wrote:To me it seems that controlling the draft through stove before the fire would be good way to go.

Yes if the stove is airtight but remember that the stove will need more attention and precise tending than if a baro damper is used.
If you choose not to use a baro damper, I would recommend a manual stove pipe damper to help keep heat in the stove. Install the manual damper in a vertical section of pipe if you can so you don't have issues with fly ash build-up like you would if it were installed in a horizontal pipe.

Because every stove installation is different, the type of damper(s) required for optimal operation can be different.

My flue pulls hard, and I dampered the 6" flue on my Kaa-2. [between the boiler outlet and baro tee].

I didn't like seeing the baro wide open and sucking heated air from the boiler room.

Dave

With the vast years of experience and the overall general high ratings for the Fields Barometric Damper I had to wonder why were my readings so weird.
The first try with the Fields BD unit were under less than optimal conditions.
Instruction sheet did not agree with the parts supplied and Tech service left me feeling less than completely satisfied this was a properly assembled unit for the horizontal location.
It was the end of a long day, the temps were in the single digits, some wind, and it was below zero the night before. This was making the basement cooler and making the associated draft in the basement feel cooler. I failed to realize that there were two new reasons for the increased air movement as I sat in front of the stove waiting for the desired result - MORE HEAT. The first was the draft going through the new BD and the second was the stove DID put out more heat and the gravity portion of the heat jacket really started to work. A 9” line off the top of the plenum.
I did notice the rapid decrease in exhaust temperature between the BD and the chimney. I failed to realize that it would take a good number of hours to reduce the temperatures throughout the chimney so that the temperature differentials would be reduced and draft numbers would drop.
As the BD did not appear to be working in 10 – 15 minutes as I expected I pulled the unit and went back to the solid cap for the night.
The second attempt went basically the same way. I wanted to see results but failed to wait long enough to allow the chimney to cool off.
Went out of town yesterday and had a break from the issues. I did reread the wealth of knowledge in the archives on Manometers, Barometric Dampers and Manual Dampers. It now seems that if I had left the Barometric Damper installed for a longer time on the first try I would not have had to bother all of you. I failed to see that the BD was actually a device to cool the chimney and reduce draft not just a hole in the side of the pipe sucking heat out of the house.
I sure hope this is the proper understanding of the BD in a coal installation. I am sure I will be corrected if not.

Test # 3 1-8-2012 10:00 AM
Outside temp 27.5 Manometer reading .085 - .09 Stove temp upper left front corner
300 degrees. Spinner opened 3/4 of a turn. Stove was last loaded with coal 9:00 pm yesterday. Stove was last shaken down yesterday afternoon about 4:00 pm. Blaschak mixed pea and nut - bagged coal. No shaking or coal additions through the night or during the testing period of about 5 hours.

Todays test started with a positive attitude that this Fields BD would work thanks to this forum. I knew the chimney was heat soaked at around 250+ degrees and would take many hours to cool off.

I installed the BD plum and level with the front weight in the left slot. I moved it all the way to the right as recommended and got a manometer reading of .04 which is a little low for the Harman Mark 111. Harman recommends a minimum of .06. I moved the weight slightly to the left and got a .06 reading at 300 degrees on the front of the stove. I almost immediately felt the reduced temperature between the BD Tee and the chimney. I soon felt increased air movement and confirmed that the BD and the heat jacket around the stove were contributing to the feeling. It was nice to see a steady .055 - .06 draft with the flapper floating about half way open. It seemed that things were finally going in the right direction. After about 45 minutes I noticed a gradual decline in the stove temp from the starting point of 300 down to about 285 – 290 hard to be accurate with a magnetic thermometer but it was trending down. This was to be expected with the reduced draft. I increased the ash door spinner opening 1/4 turn from 3/4 turn to 1 full turn. In about 1 hr the stove was trending upward and the temp finally stabilized at about 305 degrees where it remained for the rest of the test. Blue Ladies were dancing and much calmer than before.
At 2 hrs I checked upstairs temps and both heat register locations had increased their readings by about 2 – 3 degrees. Progress. Temperature outside trended down from 27.5 to 26.8 during the test run with overcast sky. No sunshine to sway the temperature increases. By the end of the test the Kitchen and Living Room were 2 – 3 degrees warmer with the stove running at 300 degrees, .06 on the manometer, flapper about half way open.
Test was a success I feel. The BD which was ready to be pitched out the window after the first 2 tries appears to have found a new permanent home in my setup.
No overdraft issues in the middle of the nigh will be nice. I have seen with the help of the manometer that this could be very possible at this location, with lower temperatures and some wind. Calmer dancing Ladies, Warmer room temps with the same stove temp are also a plus.
There appears to be a good reason that many experienced members on this forum recommend a BD. It took me a while to understand this but I am glad to have seen the light and now I can feel the heat.
Thanks again for the replies and the archives which without I would not have seen the light.

Ken

All the info. you need is here, if you can't find it or understand it just ask and everyone will help.
glad you got it under control.