Excessive Draft

excessive draft

PostBy: hgmd1 On: Sat Nov 18, 2006 6:52 pm

How would you know if you had had too much draft on a Hitzer fireplace insert. My insert is connected to a stainless steel liner over 30 feet high inside a masonry chimney. Would excessive draft lose you heat? In other words could I be sending a lot of heat up the chimney.You can adjust the air flow at the bottom of the insert but I don't know how you could decrease excessive drafting out of the stove. The insert just doesn't seem to get that hot. I have eliminated the other possibilities as I alway remove the appropriate amount of ash by shaking the grates. The larger Hitzer insert has a damper control at the top but this one doesn't.

PostBy: coaledsweat On: Sat Nov 18, 2006 7:08 pm

I think the answer is yes. Do you have a barometric damper to prevent overdraft? I think they are pretty much require with coal.
Besides, with a 30+' chimney, I think you would have a hell of a draft without a fire going.
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

PostBy: barley master On: Sat Nov 18, 2006 9:21 pm

not seeing your set up but by your description it sounds like that would roar. without a barometric you have no means for contolling draft. you have an air inlet and that is for suppling air for combustion. you could probably control your draft somewhat but then you fire would always be changing in the process. if you have a means and room for adding a baro I would do so.

what a barometric damper does is to keep a constant draft on the stove with out changing the fire and letting it burn away which a by product of that is a lot of heat being drawn outside when it is needed inside. when you light a fire draft is created. as the fire intensifies more draft is created, at a certain burn rate more draft is created than what is needed. at this point the baro will sart to open and maintain whatever you have it set at. (i set mine at-.05)

when the baro opens it keeps an -.05 draft on the stove but the draft is higher than that in the chimney. in another post I mentioned I used to have a draft gage on the stove and one on the chimney after the baro so I knew what the draft is on both. sometime the difference is zero or varies three to five hundreds. the amount that the baro is open will vary and is dependant on a couple of variables, your burn rate, atmospheric conditions and windy days.

I hear people say my baro just sits there and swings open and close constanly and I tell them thats how you know its working. without one on a windy day your fire will burn up quick especially on a handfired unit or it will start breathing because of a sudden updrafts followed by and sudden downdrafts.

when the baro is open under normal conditions and you lower the feed rate or on a manual stove are at the down side of a reload the baro will slowly close and then the stove and chimney are like in harmony working as one. if someone has set up your baro (pro) or you do it yourself and you set it at ?? you will know your draft is increasing when it starts to open and what the draft is at that point because you know the setpoint of opening providing the wind isnt ripping.

i hope this helps :)
barley master

PostBy: LsFarm On: Sat Nov 18, 2006 9:27 pm

Can you see the liner at the back of the insert?? or is it hidden behind a decorative surround?

If you can see the liner, put a stack thermometer on it, or use a laser thermometer and see what the stack temperature is. If it is over 250-300* I'd add a barometric damper in the pipe.

If the temperature is only 120-150* then you probably have ash choking your grates. Try a more aggreshive shaking action and watch in the ash pan for falling hot coals.

Davemich has a Hitzer insert, maybe he'll see this and add a bit of Hitzer knowledge.

If you have excessive draft, you should be able to get a huge flaming fire in a few minutes by opening the ash-pan damper full open. You should get 8" tall blue flames filling the firebox. If not, then you have ash choking the grate.

Hope this helps.

Greg L
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

PostBy: barley master On: Sat Nov 18, 2006 10:09 pm

greg has stated a good point about the thermometer. which just got me thinking that I need to bring up. if you use a infrared thermometer "laser" (i have a fluke 85) and your stove pipe is black take the reading there! you will be misled of the reading from a galvanized or stainless steel pipe. because what greg said I just went out to check something on my little franco im playing with in the garage for comparision of readings. the analog thermometer is reading 400* F which is 1" above the baro. connection on gal. pipe. the temp reading using the fluke at the same point is 85*F but the reading on the black pipe on the baro reads 214*F. all of these reading are taken in about a 2 sq/in area.

the other day while trying to get this thing started I kept wondering why the pipe was reading was so low and then I hit the painted part and what a big difference it was. it was then it hit me and it was something that I learned from thermography school last year and dummy me forgot. it was about the painted and non paint surface targets when using infrared equipment (cameras, thermometers) and its called reflectivity. it really distorts the actual reading and the accuarcy when the object is shiney because of the reflective interference from the units surroundings.
Last edited by barley master on Sat Nov 18, 2006 10:16 pm, edited 1 time in total.
barley master

PostBy: Cap On: Sat Nov 18, 2006 10:15 pm

I have a baro damper installed downstream of two 90's but it never opens no matter what the outside temp or or windy days. I haven't set it with a meter but have experimented by turning the weight in the direction which allows the easiest open if a change take place in the flue.

My stack temps just behind the stove after typically run at 150-200F unless I open the throttle quite a bit. I too have a 30' ss liner.

By the way, I have been installing veerneer stone on my chimney. While on the roof, I have noticed the top cap is cool to the touch with the stove running 150F on my stack thermometer.Maybe this is part of the reason I have probables drafting on warmer or damp days?

HGMD1--Try really cranking the heat for about 15 mins with your ash door open with a fresh load of coal. Then throttle it back to where you think it should be. Then keep an eye on it for a few hrs. Measure your temps coming off the vent. Should be 150-200F or maybe a little higher.What is the actual size of your firebox? I'm running a 15" x 12" box right now and see 150-200F on both the stack, water coil and hot air out. Didn't mean to hijack your thread.
Hand Fed Coal Boiler: Harman SF 250, domestic hot water loop, heat accumulator

PostBy: davemich On: Sat Nov 18, 2006 10:52 pm

HG...I have a 503 insert attached to 23 feet of SS liner in a ceramic chimney in the middle of my house. I have plenty of draft as well but as mentioned by Greg and others, you may not be shaking enough. You need to see in your ash pan 2 rows of glowing coal from front to back. That insures you have most of the ash in the pan. As you shake, keep the hopper topped. You don't want the level to drop below the shute line. I shake mine, stop, open the hopper door and feed it again to the top, put the lid on the hopper and shake again. I fill it to the top when I'm done and shake it like I just described only once a day. It gets too hot in the house otherwise. I rarely open my ash door damper more than a half inch. It keeps my 1899 SF home toastie at that setting. Hope this helps...Dave

PostBy: hgmd1 On: Sat Nov 18, 2006 11:15 pm

I appreciate everybody's input and ideas.This is a great group. Dave, I do shake the grates aggressively and have 2 rows of small red coals when I am done. The people at Hitzer told me to do this last year. As far as the insert it is covered by a liner so I can't see or measure the stack temperatures. Can you put a barometric damper in a fireplace insert where you can't get to it with the stove running? I have called Hitzer and there may be a way to try to manually dampen the stove air input into the chimney. After all the 983 stove insert has a manual damper at the top. I can tell you this. My insert never gets hot enough that it will burn you if you touch it. Also a steel kettle od water will last 4 days directly on top of the insert.

PostBy: LsFarm On: Sun Nov 19, 2006 10:38 am

Hi Hgmd, I looked up your insert on the Hitzer site. Your unit has a full jacket or shroud around the firebox with air passageways and maybe a blower.

The outer shroud and air gap are going to greatly reduce the outer skin temperature. To the point that you can put a hand on it and not get burnt.

If you want hotter air from the air vents you might be able to slow down the blower motor if it has one, or reduce the size of the intake air vents to slow down the flow.

I think that unless you have air leaks around the doors and windows, you should be able to control even a very excessive draft with just the ash door air controls. Have you checked the door gaskets?? Try using a candle or cigarette as a smoke source and go around the door and window edges and see if it sucks up the smoke.

Hope this helps. Greg L
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

PostBy: LsFarm On: Sun Nov 19, 2006 2:16 pm

I called and spoke with Davemich. His Hitzer 503 insert's outer skin gets way too hot to touch. Over 250* measured with a magnetic thermometer.

So in my above post I was wrong about the effectiveness of the outer shroud and air jacket. Something is not right.

Have you ever burned wood in this insert, and if so have you cleaned the SS liner since then?? I'm leaning towards maybe not enough draft. If you have a strong draft and a good deep load of coal, you should have one heck of a fire.

Check for air getting past the door and viewing glass gaskets. This would significantly reduce the stove's temperatures

And check the draft somehow, or have the liner cleaned, you may have a bird's nest in the top or something restricting it .

Bottom line: you should have the ability to burn a full bed of coal with tall blue flames and tons of heat.

Hope this helps. Greg L

Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

excessive draft

PostBy: hgmd1 On: Sun Nov 19, 2006 5:35 pm

I just had my chimney cleaned a few weeks ago it was clear. I can get a great fire going it just doesn't heat very well. I suspect that I am losing heat up the chimney. I think that my stove is doing what it is supposed to do. Somehow the heat is going somewhere else.

PostBy: barley master On: Sun Nov 19, 2006 6:11 pm

i too have looked at the hitzer web site for your stove.

this is from the features part for that stove.
Air intake controls
Air flows into the firebox at the ash tray and spinner controls at fire level and above the doors. This promotes efficient combustion as well as secondary burning of gases

from the picture I think this is the air wash controls? if so is this open or closed when your firing it? if open close this and see if your fire improves shortly there after

did you try opening the ash door as suggested earlier? if so what happened?

what size coal are you using?

your comment of a great fire should produce great heat.

from the outlet of the stove where the pipe enters how much room do you have? can you actually see the stainless pipe liner? if so I would find a draft gauge and a thermometer(insertion type) to see whats going up the flue pipe especially if you tried everthing listed here without positive results.

im trying to analize this problem and maybe just grasping thin air in doing so based on what has already has been posted. :?
barley master

PostBy: Berlin On: Mon Nov 20, 2006 12:22 am

have you checked for a blockoff plate where the fireplace damper used to be in your chimney, often times when relining this is not installed and the brackets/plate that hold the chimney up on the top of the flue are not anywhere close to airtight, this will suck all the heat from your insert out; this is a real problem that has occured from time to time. if not this, I would say you have some serious air infiltration, check, as ls farm said with a ciggarette, make sure everything is gasketed, if everything is ok, how good is the draft?? how "fast" can you get a roaring fire going? it should happen very quickly even with anthricite with the ash pan open.
Hot Air Coal Stoker Furnace: Will-Burt Combustioneer 77B
Coal Size/Type: Ohio BITUMINOUS pea stoker coal

PostBy: ohiocoalburner On: Mon Nov 20, 2006 6:33 pm

I am running a 503 into a shorty stainless pipe which dumps into a masonary chimmney and mine seems to draft ok. How hot is your stove getting? I am running about 200 to 250 degrees with a magnetic thermometer on the top of the stove without really pushing it. Does your blower turn on and off on automatic? I think it kicks on at or about 200 degrees. Unless I open the draft up quite a bit the blower on mine cycles frequently.

PostBy: davemich On: Tue Nov 21, 2006 7:35 am

My blower kicks in at about 120 degrees and that is per the manual. Once my fire is started and the blower kicks on it stays on. Stove top temps are at about 250-350 depending where my draft is set which I never have open more than 1/2 inch or so. Any more than that and I'm opening windows!