Terrible Downdraft

[cvaphiadis]

Hey all, first time poster here! This forum has proven to be a plethora of knowledge. First, I'll apologize for asking about something that has been discussed at length already, but I wanted to post about my specific conditions so that all factors can be considered.

I bought my house about 4 years ago. There is a finished, walk-out, basement which had a chimney access which had been plugged. Presumably for a wood or pellet stove at one point or another. I went and bought an old Huntsman wood stove to use there. Outside, there is a triple wall stainless pipe that runs parallel to my fireplace up on the floor above. They are boxed out on the side of the house and run up quite a ways. It is an 8" pipe and its about 35-40' tall. Off the stove is a 6" pipe that has a 6 x 8 " reducer where it goes through the wall (single wall black pipe inside). When it is very cold in Northern New York, and last night was -20F it can be an issue. Once the draft is reversed, I have no issues and the stove burns beautifully. However, priming it can be challenging. Typically when its in the teens or higher I can crack a window, fill the stove with newspaper and light it with a torch while shutting the doors it takes off pretty well, following up with kiln dried kindling. But this morning I filled the room with smoke trying to get it started, and the stove hadn't even cooled down entirely, though the pipe was stone cold.

I've seen draft inducers, which are not revered too well in the wood burning applications, and even seen the "draft collars" which are crazy expensive and I can't help but think there must be a better way. I will say that my house is quite drafty, unfortunately, it's old. The room the stove is in is block and only has cheap open core foam insulation behind the paneling. One wall is under-ground (I'm built on a hill w/ slab on grade). I tried to prime it with a map gas torch with no luck and am no considering a blow dryer or heat gun, but am not optimistic. If anyone has some suggestions I'm open!

One other thing to mention is that the propane furnace is on the same floor and its open air throughout. There is a return grill cut into the return plenum, so there is a vacuum being created from that as well.

Thank you all in advanced for your help and knowledge.

 

[MR. GLO]

Basment stove..you need a ultra low co meter. If you have a cold flue syndrome and in basement you probably will get some co2 on certain days and coaling. Possibly on reloads too...but you won't know this unless you have a ultra low co2 meter and constantly watching it. Some have a memory but that doesn't tell you when the co2 came.



Smoke on startup easy fix.... preheat the flue.. The easiest way is small heater in middle with a plywood face or candle or let a 1.00 Firestarter burn....an easy way to know when flue ready is auber flue probe. But with a new heater 5 mins is enough for me.

The cold air is dropping in the chimney..

 

[fire_man]

I second the idea of putting in an auber flue probe. I have a sensor bolted to the outside of the flue pipe and wait for the temperature to rise at least 5 degrees and then I know the draft is good.

 

[neverstop]

Hey all, first time poster here! This forum has proven to be a plethora of knowledge. First, I'll apologize for asking about something that has been discussed at length already, but I wanted to post about my specific conditions so that all factors can be considered.

I bought my house about 4 years ago. There is a finished, walk-out, basement which had a chimney access which had been plugged. Presumably for a wood or pellet stove at one point or another. I went and bought an old Huntsman wood stove to use there. Outside, there is a triple wall stainless pipe that runs parallel to my fireplace up on the floor above. They are boxed out on the side of the house and run up quite a ways. It is an 8" pipe and its about 35-40' tall. Off the stove is a 6" pipe that has a 6 x 8 " reducer where it goes through the wall (single wall black pipe inside). When it is very cold in Northern New York, and last night was -20F it can be an issue. Once the draft is reversed, I have no issues and the stove burns beautifully. However, priming it can be challenging. Typically when its in the teens or higher I can crack a window, fill the stove with newspaper and light it with a torch while shutting the doors it takes off pretty well, following up with kiln dried kindling. But this morning I filled the room with smoke trying to get it started, and the stove hadn't even cooled down entirely, though the pipe was stone cold.

I've seen draft inducers, which are not revered too well in the wood burning applications, and even seen the "draft collars" which are crazy expensive and I can't help but think there must be a better way. I will say that my house is quite drafty, unfortunately, it's old. The room the stove is in is block and only has cheap open core foam insulation behind the paneling. One wall is under-ground (I'm built on a hill w/ slab on grade). I tried to prime it with a map gas torch with no luck and am no considering a blow dryer or heat gun, but am not optimistic. If anyone has some suggestions I'm open!

One other thing to mention is that the propane furnace is on the same floor and its open air throughout. There is a return grill cut into the return plenum, so there is a vacuum being created from that as well.

Thank you all in advanced for your help and knowledge.

Sounds like negative pressure issues. Probably should install an outside air intake for the furnace at least. Would most likely be beneficial for the stove as well. In the mean time you can test if an oak would help the stove by cracking a window near the stove for a couple minutes prior to attempting to establish draft. I find a heat gun to work well for heating the flue, if you feel the heat being blown back at you then you haven't established draft yet. Once you've established draft then light the stove and you shouldn't get smoke rollout.

Also, you shouldn't be increasing pipe diameter. That will reduce draft. If the stove requires 6" it should be 6" ID all the way to the cap.

 

[MR. GLO]

On my setup i tried an outside air intake on basement and it caused the chimney and co2 to get worse at coaling stage on very cold day because you are causing cold air to enter the stove and flu

And most likely the Co2 will not go out the fresh air intake and with cold flue go into basement

Adding small amount of air to basement would be OK to offset the other appliances but unfortunately the oak might not be best way and your only co2 issue could be stove even with negative pressure.

 

[cvaphiadis]

Sounds like negative pressure issues. Probably should install an outside air intake for the furnace at least. Would most likely be beneficial for the stove as well. In the mean time you can test if an oak would help the stove by cracking a window near the stove for a couple minutes prior to attempting to establish draft. I find a heat gun to work well for heating the flue, if you feel the heat being blown back at you then you haven't established draft yet. Once you've established draft then light the stove and you shouldn't get smoke rollout.

Also, you shouldn't be increasing pipe diameter. That will reduce draft. If the stove requires 6" it should be 6" ID all the way to the cap.

I don't really have a choice with the pipe diameter. I would have to get a different stove or tear the box off the side of my house to change it out. My furnace is a high efficiency PVC vented unit with a concentric. So it draws outside air in, but it's totally enclosed in the cabinet. I will try the heat gun.

 

[MR. GLO]

The heat gun will work but be ready for ash blowback...for your first time try to reduce the ash in stove and point it up at angle.

 

[stoveliker]

Just because it's a safety issue: the discussion above is about a CO detector, not a CO2 detector. Possibly you knew, but better safe than sorry.

Regarding the OAK: note that those can never rise. I.e. if the wall nearby is below grade, you can't put an oak in. It might function as a chimney, with associated fire risk.

 

[begreen]

First see if the negative pressure can be remedied if there are some direct causes. Some of these are leaky windows or attic door upstairs, bathroom fans open to outdoors with no damper-flap, etcl. If the reason for the negative pressure can't be resolve then an HRV in the basement may be a workable solution.

 

[Max W]

It happened at -20. Do you by any chance live in a valley or a geography affected by temperature inversions? They make it difficult for air to rise. Coming down the hill to work in a slight valley on very cold mornings I would see chimney smoke lying flat just above the houses. It was like a lid was put on the air.

 

[neverstop]

The heat gun will work but be ready for ash blowback...for your first time try to reduce the ash in stove and point it up at angle.

I point the heat gun above the baffle directly at the bypass, I never get ash blowback doing that. Assuming the stove design allows that.

Expanding the pipe id will allow the exhaust gas to expand and cool reducing draft. Does the stove call for 6 or 8"?

 

[stoveliker]

It happened at -20. Do you by any chance live in a valley or a geography affected by temperature inversions? They make it difficult for air to rise. Coming down the hill to work in a slight valley on very cold mornings I would see chimney smoke lying flat just above the houses. It was like a lid was put on the air.

Yes, inversion layers are common in valleys.

 

[FPX Dude]

Negative pressure sucks, no pun, but use a hair dryer up the flue to get it going right.