pulling air from the leeward side

[southbalto]

I installed my stove back in 2009 and have been pretty happy with its performance. Just to get it out of the way- the wood I’m using is a mix of poplar and red oak CSS in 2010.

I’m running a jotul 400 rear vented into a prefab chase using a Class A system. The chimney run is roughly 21’ in total, but draft is impacted somewhat by a 30 degree offset which begins maybe 4’ above the stove. The first time I ran the stove it was a smoky mess! Shortly after the match hit the kindling smoke was bellowing out of the intake. This problem went away after installing an outside air kit. I’ve tried running the stove with using inside air a couple times since and had similar results…. Extremely sluggish starts or smoke out the air inlet. As I mentioned above, I’ve been pretty happy with performance, though, I still feel like I’m not getting enough airflow. It can take an hour or more to get the stovetop up to 500. I went as far as to buy an inexpensive endoscope and run it through the stove to make sure there are not blockages!

What’s been really frustrating is that periodically I get these fantastic burns….quick starts strong secondaries, ect. I noticed last week that during one of these good burns the winds were coming from the east, which is the side the chimney and OAK are on. I’m wondering now if negative pressure on the east side of the house (our prevailing winds are from the west) is impacting the stove’s performance. There are no windows on the west side of the house. I guess my options are:

• Remove the OAK and crack open a window on the north wall in the stove room
• Reroute the OAK to either the north (much shorter run) or south wall
• Accept the fact that inconsistent burns are the norm for woodstoves

Anyone have an issue similar to this? Will running the OAK all the way to the windward side really make a difference?

 

[rwhite]

I suppose if cracking a window gives consistent burns then the OAK may be the problem. Is the house on a stem wall foundation or solid? I wouldn't think that running and OAK to the west side would help as it seems to me that you will be attempting to pull a long volume of air. If the house is on a stem wall maybe you can run the OAK through the floor and vent the west side of the foundation.

 

[begreen]

If opening a nearby window improves burning it could be the OAK needs improvement. Is the stove rear-vented or top? Describe the current OAK setup. How long is the current OAK run? How many 90 deg. turns? What size pipe? How does it terminate outdoors?

 

[southbalto]

If opening a nearby window improves burning it could be the OAK needs improvement. Is the stove rear-vented or top? Describe the current OAK setup. How long is the current OAK run? How many 90 deg. turns? What size pipe? How does it terminate outdoors?

Stove is rear vented into the Class A Tee. I believe the OAK pipe is all 4". The current OAK begins with a 90 at the stove inlet:

It runs 18" back through the wall into another 90 heading down below the chimney Chase (Here I'm standing below the chimney chase looking up at the clean out portion of the chimney):

It terminates 18" below that final 90 degree bend:

 

[southbalto]

It's frustrating.... I feel like I should have pretty good draft with a 21' insulated run and i'm getting readings of 12-16% on my wood. I've checked the cap several times this year and I haven't had any issues in the past with excessive creosote. I'm not sure why I have to fight the stove sometimes to get it going and up to crusing temp.

 

[begreen]

With its shallow firebox the Castine likes a strong draft when rear vented. Ours was rear vented, then straight up 20ft. It drafted ok until temps were over about 45F. Over 50F it drafted pretty poorly. Your stove has the additional horiz run which hurts. Can you increase the pitch of that horiz pipe uphill toward the stove?

 

[southbalto]

With its shallow firebox the Castine likes a strong draft when rear vented. Ours was rear vented, then straight up 20ft. It drafted ok until temps were over about 45F. Over 50F it drafted pretty poorly. Your stove has the additional horiz run which hurts. Can you increase the pitch of that horiz pipe uphill toward the stove?

yea, actually, I started a new thread a month or so ago on potentially reconfiguring my hearth. I was thinking I might tear out the drywall and wood studs and replace with durarock and metal. I'd then raise the entire class a system and reconfigure the stove pipe to vent up 3' or so before making the 90 into the thimble. If that didn't solve the issue I suppose it would be easier to make that configuration work with a different stove.


begreen- Did you notice a significant difference in the ease of startup or the strength of your secondary combustion with the PE?

 

[begreen]

The F400 worked pretty well for us when temps were 45F or lower. Heating up to secondary combustion was quick as long as the wood was fully seasoned. We had a run in with some damp maple with that stove too and the difference was dramatic, just like it was with the PE. The PE is top vented and I can run it at 55F if I want. The T6's secondary combustion is good, but not as dramatic as the cascading fountains of fire that you get with the Castine's manifold.