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Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 4:19 am
by jpete
When trying to idle this stove down, I am having a CO problem. The alarm goes off and I can smell sulfur in the house. I can run the stove hot but not at a low idle. The weather has been up and down so it's fairly often. I'm running a Harman Mk I with a MPD. I ran this same set up with no problem for 6 or 7 years but I'm in a new house with a new chimney and the teething pains are starting to get to me.

The chimney is a 21' outside masonry chimney with a 6"x6" terra cotta lining.

Is this where the baro comes in? Should I put a chimney cap on?

I was looking at the Field Controls site and it says for a chimney taller than 16', use the next size up (7") baro. Can this be accomplished simply by using adapters on either end of the pipe the baro would got into or should it increase right from the stove and then back down at the thimble.

I can post pictures if that would help. I appreciate any help, getting up to the CO detector at 3am is not fun.

Thanks

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 7:20 am
by coalkirk
jpete wrote:I'm running a Harman Mk I with a MPD.
Does that mean a manual damper? Not supposed to use one. Get rid of it and install a baro and set it with a manometer. I assume you've checked the chimney for obstructions? Checked the door gaskets for condition? You say it's when you try to idle the stove down. Does that mean you are closing the manual damper down? If so that's probably the reason. To idle the mkI down, do it with the combustion air inlet cap. You could also turn off the fan or run it on a thermostat.

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 8:24 am
by Devil505
Make sure your stove is getting enough air to burn where it's a new house. Sometimes you have to burn it hotter than you'd like to get the draft going good on warm days too.

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 9:59 am
by jpete
coalkirk wrote:
jpete wrote:I'm running a Harman Mk I with a MPD.
Does that mean a manual damper? Not supposed to use one. Get rid of it and install a baro and set it with a manometer. I assume you've checked the chimney for obstructions? Checked the door gaskets for condition? You say it's when you try to idle the stove down. Does that mean you are closing the manual damper down? If so that's probably the reason. To idle the mkI down, do it with the combustion air inlet cap. You could also turn off the fan or run it on a thermostat.
Yes, it's a manual damper. Like I said, I ran it at my other house with no problems for years. When I say idle it down, I mean I only have the air inlet knob open 1/2 to 1 turn. Outside temp was around 30* last night. We are expecting temps in the mid 40's to low 50's today so I didn't want to have the stove cranking.

Now you have me thinking about the door gaskets. I thought I replaced them this season but it might have been the beginning of last season.

Unless an animal crawled in there, I don't think it's a chimney obstruction. I cleaned it at the beginning of the season and the stove runs fine when I let it run.

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 11:24 am
by Freddy
You got lucky at the old house. It's time for a barometric damper. My $.02

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 11:31 am
by titleist1
Something else to think about in addition to the others posts.....Is the new house much tighter than the old house? Maybe the stove is starved for combustion air and that creates problems when idling. ...edit.....sorry Devil....missed your post with the same idea initially...

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 12:21 pm
by Uglysquirrel
One thing not discussed too much is the basement chimney clean out vent, make sure the door is latched with a good seal, my door has a couple layers of duck tape over it and the surrounding concrete to ensure the baby is sealed big time, air intake at this location will lower the draft.

Hope this helps.

bruce

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 12:43 pm
by jpete
Now that's something to think about. I know the clean out door on that side of the chimney is basically not even attached. Just kind of propped up with a brick holding it from falling over.

Re: Stove Giving Me Problems

Posted: Sat. Nov. 29, 2008 12:46 pm
by jpete
titleist1 wrote:Something else to think about in addition to the others posts.....Is the new house much tighter than the old house? Maybe the stove is starved for combustion air and that creates problems when idling. ...edit.....sorry Devil....missed your post with the same idea initially...
It's probably a bit "tighter". My old house was built in 1951 and had no insulation in the walls with about 4" in the attic. This house was built in 1973 with insulation in the walls and around 10" in the attic. I opened the window next to the stove just a crack to try to see if that was the problem.

Re: Stove Giving Me Problems

Posted: Mon. Dec. 01, 2008 7:01 am
by captcaper
Was the chimmey built after the house was built? The chimmey I had built on my old house was built wrong. It didn't clear the roof like the codes said for one. Another is I was in a crowded area and had a tree right next to the house plus the liner was 8x8 tile. This new one I have clears the peak by almost 4 ft. and is 6" SS with 1" insulation and works so good.
Coalkirk I can't see why a MPD is so bad. If you look at the air intake hole and the MPD holes and gaps around the damper inside the pipe I would think it is enough to let the burned air by. You can see the dancing ladies behaveing to prove there is good draft with the MPD closed. I never had a problem with a MPD. Only the chimmey before mentioned above. Even with the MPD open all the way the chimmey would draft badly on SW winds on warmer days. It would even blow back steadly into the room. Once the winds changed from the S or SW it would work fine.
Now that I have used this setup since Oct. and have a feel for it I'll try opening the MPD and adjusting the air intake to see how it burns to compare.

Re: Stove Giving Me Problems

Posted: Mon. Dec. 01, 2008 8:46 am
by LsFarm
Manual dampers don't control draft,, they throttle air flow.. You need to control maximum draft for an airtight stove.. there is very little airflow through an airtight stove.. But the draft can vary widely with wind and temperature changes..

A manual damper had a place in the days when stoves were not airtight, and you couldn't control incoming air to the fire,, so you slowed the rate of flow up the flue pipe with a manual damper.. The barometric damper was designed to limit draft for automatic appliances burning oil and gas, where draft was critical.

Our new airtight coal stoves are much easier to control and adjust burn temps and burn rates with a barometric damper..

Greg L

Re: Stove Giving Me Problems

Posted: Mon. Dec. 01, 2008 9:38 am
by CoalHeat
jpete, I have a similar set up and chimney as you, although mine is taller.

Get rid of the manual damper, Harman specifically forbids the use of one with this stove. Install a baro and set it with a manometer to -.05" WC with a full fire and a warm chimney. Mine has been poking along with the air open 3/4 of a turn, the blower off, using Harmony nut coal. The baro is open quite a bit.

The MPD is restricting the flow of hot gases into the chimney, the chimney is cooling off, the result of that is the drafting ability of the chimney drops like a rock. With the baro the flow of warm air up the chimney will be constant, the chimney will stay warmer and the result will be more draft.

Use the MPD as a doorstop.
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Re: Stove Giving Me Problems

Posted: Mon. Dec. 01, 2008 8:08 pm
by jpete
Thanks Wood'nCoal. I'd like to do this "right"(where right means whatever works) but I had a question on the baro dampers. On the same page you got your diagram from, http://fieldcontrols.com/draftcontrol.php if you go all the way down to "Choosing the right size", they have a graph which states for a 6" flue, with a chimney height above 16', use a 7" damper. My chimney is 21'.

How would this be accomplished in your opinion?

Use a step ring before and after the piece with the baro? Step up just after the stove collar then back down just before the chimney? Use a T like in the diagram and a step ring behind the baro to mate it to the 6" pipe?

I hate spending money twice and would like to get an informed opinion before I do.

Thanks.

Re: Stove Giving Me Problems

Posted: Mon. Dec. 01, 2008 9:59 pm
by CoalHeat
I guess I missed that graph, which probably explains why my baro stays so far open all the time. :doh:

I'll leave the final say up to the other experts here as far as installing the 7" baro, but I think you can just get a reducer to fit the baro and plug it into the 6" pipe.

Your chimney is probably like mine...once it warms up the draft is like a vacuum cleaner.

Re: Stove Giving Me Problems

Posted: Mon. Dec. 01, 2008 10:10 pm
by rockwood
Woodncoal is on the right track here.

The main problem is the chimney cooling off and not making good draft, a common problem with exterior chimneys
I think a six in baro damper would be fine but I can't say it will fix this draft problem.

Good thing it's a 6x6 flue, any larger and the problem would be even worse.