Issues with negative pressure

[jds015]

Any helpful suggestions, ideas, tips, etc. are appreciated. First off we have a Drolet Savannah, that has double wall stove pipe that rises vertically about 4' and then elbows out and goes a total of about 3.5' through the wall, then elbows up again for about 18' on the exterior in triple wall pipe. This is our third season with it and I've inspected the chimney (I have posted pictures in the past of the pipe after last season) and it has been fairly clean. What happened lately was that I have noticed burns have been slower the past several days, and then last night I had opened the stove to turn some pieces of wood to assist in burning and noticed negative pressure to the point smoke was coming out the connections in the pipe, not just out the door in my face. Once I closed the door, proper draft again. Temperature was a bout 45 degrees with high humidity after a day of rain and rising temps from the 30's during the day. There was a decent breeze too. So I thought, maybe weather conditions? Got it burning again and it seemed okay. I let it die during the night and decided to inspect the clean out on the outside today and tons of black junk fell out. I looked up the chimney and took photos with my cell phone so I could see into the "through the wall" pipe. The chimney has some stuff on it, but not much and nothing that causes concern to me, not hard build up, but real light stuff that I brushed right off with my hand. The through the wall pipe did have a decent amount of ash that had accumulated on the bottom and I brushed it out and vacuumed it out from the exterior. So, I thought the accumulated ash and creosote sitting on the clean out was possibly obstructing the elbow and thus was creating my draft issue. So this evening, temp was around 50 outside, had been a warm day around 60 but drier and thought I'd try again as its going to be cold this week. Maybe I didn't get the chimney warmed up enough, but even my small fire I was lighting was once again reverse drafting on me and not only coming out the door, but through the connections in the stove pipe too. Besides these two instances this has only happened once when my wife was determined to build a fire on a 60 degree, windy, high humidity day. I have lit fires many times during conditions like todays and can't understand why I am having a draft issue? Yes, I try to burn dry, seasoned wood. Sometimes I burn what I have available, but 95% of it is at least 1 year old or more, split, stacked, and in the hot summer sun, don't use much oak cause of the long dry time, lots of maple, soft mostly with some hard, ash, bradford pear even, elm, poplar, cherry (yes about anything other than gum). I have been using more scrap kindling which I was given which is dried pine scraps mostly. We haven't had the chimney swept and I do speculate that the cap may be beginning to get clogged, or the baffle in the stove itself may be collecting junk? Any other thoughts? Suggestions? Thank you for any responses.

 

[JA600L]

How leaky are your stove pipe joints? I would seal that up. Sounds like your draft reversed. Could be a tight house, stack effect, weather etc..

 

[jatoxico]

Check the cap. If you can't get on the roof use binoculars. Weather may not be helping but sounds like you're due for a cleaning.

 

[begreen]

^^^This^^^ Check the cap screen for plugging. We've had a couple incidents of this happening this season. Same symptoms.

 

[jds015]

Everyone, thank you for the responses. JA600L, not sure how leaky the joints are as I have only witnessed smoke come out of them twice, those times I mentioned, and my wife experienced it once too. I would love to seal them up better if possible. Anyone who can suggest what to do in order to do that would be most appreciated! That could certainly help the situation. The house isn't so tight, as there are literally a couple of small holes in the floor even. The part of the house that the stove lives in is 105 years old and while its insulated well and we have storm windows over single pane windows, its still, well 105 years old and lets us know it when the wood stove isn't in operation. Our propane gas pack likes to run A LOT, which is one of the reasons my wife and I love our Drolet.

Jatoxico and begreen I have a strong suspicion that is the problem. I haven't looked with binoculars yet, but I feel strongly its likely the culprit just due to the fire behavior. One other thing was that I stuck my hand up in the baffle as much as I could and felt ash laying in it. Is there a good way to get this out? Vacuum from the interior? I sucked the through the wall pipe out from the exterior. The baffle is welded in and its not going anywhere, but any suggestions of how to deal with that issue? I may look at a chimney broom from lower or home depot to try to reach the inside of the cap and the pipe. Luckily, my clean out and set up are very easy to access. I'm also looking for a chimney sweep, but most are booked up for weeks in advance. Thanks again for any suggestions anyone. This place is an awesome resource, so thank you everyone.

 

[begreen]

If there is a lot of ash on top of the welded baffle it may take removing the stove pipe and vacuuming out the baffle top with a flexible tube. However, if there is just a little up there, then maybe just let it be.

 

[jds015]

Everyone, thanks again for earlier responses. We called a chimney sweep to come and clean things this week, which while in theory was good, I feel that we got taken and the individual didn't do a complete job. My wife was home when he came, but she said he did clean everything inside well, removed the stove pipe, cleaned the baffle in the stove top, ran a video line into the chimney pipe and she says he had a brush that he ran from inside. Was I wrong in thinking that a standard cleaning would include going outside and removing the clean out and running a brush up the chimney and cleaning the cap? He failed to do both these things, which I didn't realize until last night. We decided to fire the stove back up since he had come and we thought all was good, but still had the same problem. I finally thought, after looking up at the cap, that maybe he didn't clean it? Sure enough, I contacted him and he didn't clean it from the outside. I went up a ladder with a broom and cleaned the screen, because as most of you can guess, that was indeed the problem. It was gunked up pretty badly. I was able to clean it considerably and this time when we relit the stove the fire behavior was completely different, for the better. Draft was good! Flames were shooting straight up and smoke was not coming out when opening the door and best of all no smoke coming out of the seams. So, my question now, how difficult is it to get your own brush and clean your own chimney and cap? I think we still need an annual inspection by a professional (not this guy though) just to make sure all is well. Any additional pointers are welcome. Thanks again.

 

[begreen]

Good to hear that at least you found the issue. Anytime in the past for any chimney cleaning it's always been top down. Now I clean my own. I did remove the chimney cap screen because we are wet in the winter so sparks are not a concern and I don't expect a brush to to a good job on a cap screen from below. I use a Sooteater which is well covered in other threads. It attaches to a drill and does a decent job of sweeping in our almost straight up metal chimney.

 

[jatoxico]

I went up a ladder with a broom and cleaned the screen, because as most of you can guess, that was indeed the problem

I see many of those caps with a wrap of wire mesh that seems prone to clogging. Lousy design IMO. Sweep should have cleaned the cap. He must know that they are a likely problem spot.