Smoke seeping from Security DL Chimney seams?

[Skibum]

We have installed a Jotul Oslo wood stove in our home with Security Chimney DL stove pipe. The stove burns clean and hot and appears to be operating normally.

Jotul Oslo stove with outside piped fresh air connected to 20 feet of Security DL pipe.

The pipe has been suspended from the roof box and each piece has been twist locked together with a single set screw per the manufacture's recommendations.

Unfortunately when we turn on our kitchen range hood vent it draws smoke into the residence. When the hood vent is on a large amount of visible smoke in drawn from the chimney pipe seams. If the Hood vent is on for more then a few minutes the smoke fills the home and activates the smoke alarms.

Contributing factors may include the length of the DL pipe, strength of hood vent and the house is very air tight with spray foam wall insulation.

Anyone have any thoughts for a fix?

 

[HotCoals]

Wow.
Seeing how you already have the outside air kit you would think the exhaust fan would have no effect.
Connections are good with the O.A.K.?

 

[HotCoals]

One question I would have for you though ..
Does the primary air and the secondary air both come through the O.A.K.?

 

[oconnor]

Your double wall isn't going to generate the draft that chimney sections would. You may need to consider adding a make up air fan in series with your range hood to add air to the room at the same rate that the fan removes it. Ideally, you would also increase the amount of chimney you use vs connector pipe. The chimney will retain more heat therefore generate more draft.

 

[Skibum]

• I believe all of the air comes in through the 4 inch air intake on the bottom of the stove. The pipe drops into the floor to a 90 bend and then heads outside. The total pipe length is around three feet
• Getting a fire started doesn't seem difficult and the draft usually picks up pretty quick.
• We have been contemplating a fresh air inlet to the kitchen range but before the Sawzal came out wanted to see if others had experienced this problem. I have had wood stoves through out my life and never had or heard of this issue.
• Is the exhaust fan too powerful for a tight house. The DL pipe connections seemed pretty tight when installed.

 

[Fireshoppe]

There is no residential air tight chimney system and even if there were the fan would pull smoke out of the air intakes of the stove instead. i.e the chimney is the only source of make up air available to the range hood. Thus the only fix are 1. don't use the range hood. 2. provide make up air close to the range hood (under the range perhaps)

 

[HotCoals]

There is no residential air tight chimney system and even if there were the fan would pull smoke out of the air intakes of the stove instead. i.e the chimney is the only source of make up air available to the range hood. Thus the only fix are 1. don't use the range hood. 2. provide make up air close to the range hood (under the range perhaps)

He has a oak and he thinks the primary and secondary air is feed through that.
If that is true you mean to say that kitchen fan can suck the smoke right out of the pipe joints?(reverse draft maybe?)
If so that must be one strong fan!

 

[oconnor]

Happens all the time in new construction houses. The stove likely moves 40 to 100 cfm of air, while the range hood could move ten times that. It could out such the OAK and the flue.

I also noted the stove manual recommends no more than ten feet of connection pipe in the install. The cooling that occurs can reduce draft significantly.

 

[Dustin]

A small experiment you can do, to see if make up air will solve the issue.

With the stove burning, and the range hood running and pulling smoke through the chimney joints, open a door or a window to the outside, and see what that does

 

[Fireshoppe]

A chimney functions solely because the warm air inside is lighter and thus the air pressure is lower than that in the structure. If the stove burns normally otherwise that means it has adequate draft and there are 2 likely causes for smoke seeping from the joints. First is a plugged cap or upper section of flue. And the other is lower pressure in the structure than in the flue. In this case a draft fan.

 

[HotCoals]

A chimney functions solely because the warm air inside is lighter and thus the air pressure is lower than that in the structure. If the stove burns normally otherwise that means it has adequate draft and there are 2 likely causes for smoke seeping from the joints. First is a plugged cap or upper section of flue. And the other is lower pressure in the structure than in the flue. In this case a draft fan.

Even though the stove is getting it's air from outside? Interesting.

 

[Fireshoppe]

Which is likely why the power draft is not pulling smoke (assuming here since nothing was mentioned) from the stove itself. The stove continues to burn well because it still sees negative pressure at it's outlet and has a fresh supply from outside. The draft hood pulls smoke from the flue because it is an easier source than though the draft controls of the stove. An open window near the hood should tell the tale.

 

[HotCoals]

Which is likely why the power draft is not pulling smoke (assuming here since nothing was mentioned) from the stove itself. The stove continues to burn well because it still sees negative pressure at it's outlet and has a fresh supply from outside. The draft hood pulls smoke from the flue because it is an easier source than though the draft controls of the stove. An open window near the hood should tell the tale.

Ok..that clears the air some,thanks and it gives the poster something to try and hopefully it clears the air some for him also.. Cheers!

 

[Skibum]

Thanks for all of the advice. I was on the same track but figured I should bounce it off others before I put in a air vent for the hood.

The air king rang hood moves 500 cfm. If we open a window or door it doesn't draw it from the stove pipe. I guess the house can't support the flow.

Even with the hood on the fire burns normally due to the tight outside air intake as fireshoppe mentioned.

Thanks again all of the help.

 

[Highbeam]

I don't know if you have gas powered devices in your home such as a water heater or furnace but if you do, you should know that those flues are likely backdrafting as well and spewing CO into your home which isn't as obvious as woodsmoke but much more deadly.

 

[Skibum]

I don't know if you have gas powered devices in your home such as a water heater or furnace but if you do, you should know that those flues are likely backdrafting as well and spewing CO into your home which isn't as obvious as woodsmoke but much more deadly.

Yes we do have gas appliances which are located in other areas of the home. Never thought about the hood vent pulling from them. We do have three CO detectors in the residence but that is still a concerning thought.

Thank you

 

[bag of hammers]

I don't know if you have gas powered devices in your home such as a water heater or furnace but if you do, you should know that those flues are likely backdrafting as well and spewing CO into your home which isn't as obvious as woodsmoke but much more deadly.

Sanity check appreciated - this also applies to direct vent gas appliances? I assume it doesn't matter - a powerful range hood can still cause issues?

 

[oconnor]

Give this a read http://publications.gc.ca/collections/collection_2009/schl-cmhc/NH15-436-2008E.pdf

There is a good section on vent fans and chimneys.

Edit - that isn't the document I was looking for, but I can't find the right one. Sorry

 

[begreen]

Sanity check appreciated - this also applies to direct vent gas appliances? I assume it doesn't matter - a powerful range hood can still cause issues?

Yes, this is a strong negative pressure that needs makeup air for compensation. A passive air room air intake with a flapper valve should cover this issue.
(broken link removed to http://www.fieldcontrols.com/mas.php)

 

[bag of hammers]

Thanks for the add'l info. Not sure if it's just me, but it seems really easy to just assume that an OAK or similar (e.g. direct vent) is going to solve any such problems, when that's apparently not the case. My bathroom fan (@ 70 CFM) has no effect on draft, no smoke or CO detectors going off, etc., so I wonder it that just lulls me even farther into a false sense of security? My kitchen renovation could put me over the edge (good range hood is on the list). I'm glad the OP raised this question.

 

[begreen]

500cfm is a very strong exhaust blower for residential use, especially if there are other exhausts for bathroom, clothes dryer, etc.. Would it be possible to replace the blower motor with a 200 cfm motor?

 

[Highbeam]

500cfm is a very strong exhaust blower for residential use, especially if there are other exhausts for bathroom, clothes dryer, etc.. Would it be possible to replace the blower motor with a 200 cfm motor?

Or a similar sized, 500 cfm, fresh air blower bringing makeup air into the home. The idea is not to put your home into a suction situation. It is hard to believe that there isn't some sort of code for dealing with make up air when installing a 500 cfm vacuum.

Backdrafting through the old natural draft type gas tank water heaters was especially easy.

 

[begreen]

A simple flapper vent should provide the makeup air. If you want to get fancier and more efficient use a passive HRV.

(broken link removed to http://www.fieldcontrols.com/mas.php)
(broken link removed to http://www.fieldcontrols.com/mas.php)

 

[Heatsource]

Yes, this is a strong negative pressure that needs makeup air for compensation. A passive air room air intake with a flapper valve should cover this issue.
(broken link removed to http://www.fieldcontrols.com/mas.php)

or
http://www.amazon.com/Chimney-41800-Make-up-Supply-Ventilator/dp/B001D1J7AE