Problem firing older Hearthstone - house gets smokey as fire dies down

[ZenFire]

Hi all, I appreciate you reading this.

I had an older Heartstone (Pheonix I) installed in a new home and this is my first fall firing it up. I've fired it up twice now and had the same problem both times: it starts fine and burns very well. When the house is warm enough and I don't want to add more (after ~3 hrs), I left the fire die down on its own and around this time the house gets smokey. I can't quite figure out what I'm doing wrong or if there is something not right with my set up. Since its not smokey at the start up, I know my draft is OK, although I have found that when I'm starting up the fire it helps to leave the door open a crack to really get it going and encourage draft.

Other things that might help: the house is super insulated and generally airtight. I had an outside air adapter made by Hearthstone installed onto the stove, so there is outside air going directly into it and that is (I think) fully open throughout. The stove pipe is double wall and has a 45 deg bend and then goes straight up a ~16 foot stretch and then through a square support through the roof.

Does this sound like a common problem? What can I do to reduce smoke or encourage draft? There are sure to be times when the fire dies down after we are asleep, so I really want to get this figured out. Any advice or help is appreciated.

Thanks,
Mark

 

[begreen]

Sounds like this might be draft reversal. What are the outdoor temps when this happens Mark?

 

[ZenFire]

Thanks for responding!

It hasn't been that cold, actually. Maybe 50F or so. I'm mostly trying to warm my house up in the evening so it isn't chilly in the morning. I live in the Finger Lakes and it gets cold at night and warm in the day this time of year. Does that sound like draft reversal? I haven't heard of that before.

 

[begreen]

Could be. If so, this condition should improve with lower outdoor temps. When this happened was anything else sucking air out of the house like a kitchen exhaust fan, bath fan, clothes dryer?

 

[ZenFire]

Yes, most likely the bath fan was on and the dryer was running today, not sure about the first time. Because the house is so air tight its actually recommended that we keep that bath fan on a timer and run it X hours per day. But it makes sense - do the fan and dryer compete with the draft of the stove?

 

[peakbagger]

Yes it does. A super tight house has a tough time with wood stoves unless there is air to air heat exchanger make up air system which may need to be upsized to deal with the woodstove. When an exhaust fan is running it pulls air from the path of least resistance and that's the stove when its dying down. If you are having these issues its a possible sign that you are too tight and that can lead to sick building syndrome. Just running exhaust fans without a properly designed air makeup system is asking for trouble, the mobile home industry loves to do that and inevitably it doesn't work that well.

 

[blades]

Old standby method- crack a window open- see if that resolves difficulty. Draft reversal- quite common in milder temps- most of the time it is a basement unit someone is asking about. At start up it can also be called a cold plug. requires pre heating flue to get things going in the right direction. Dryers pull a lot of air , but no one really thinks of them in relation to a stove ( they pull more air out than any of common kitchen or bath fan units from Broan or Nutone others as well) I do not think I have ever seen a cfm listing for any dryer. Very tight houses is one of the reasons that radon has become such a big issue, combined with the totally sealed combustion units of current HE furnaces and water heaters there is no automatic air to air exchange taking place. In some areas new builds are required to have hrv units installed tied into the cold air return line of the conventional furnace. I have one in my new to me home - going to be a learning curve on that. Course that particular MFG is no longer around- typical problem for me. One of the blower motors on it was burned out - that has been replaced , so now to get more information on how to set it up cfm wise. O f course this leads to the age old debate about OAK ( outside air connection) directly to heating appliance- In your case, tight house,its a no brainier if the appliance has an input for that it should be installed.( heck of a lot cheaper than a HRV and beats a window open with resulting cold air draft.) just my thoughts.

 

[ZenFire]

Thank you so much. I'll keep an eye on the temperature and other sources of air pull in the house to see if that resolves it next time. I'm not sure if our dryer has an input for outside air, I've never even heard of that for anything except a wood stove. I'll look into it.

I've heard of 'sick building syndrome' and I'll look into it further. Our builder was very knowledgeable so I would think our house has been made up to current standards but I don't know enough about air exchange to have definitely asked the right questions in construction.

I really appreciate you both taking the time to answer, this has been very helpful. If anyone else has other advice or suggestions, I'm all ears.

 

[kennyp2339]

Your outside air connection is level with or lower than the base of the stove?

 

[ZenFire]

Its either level or just a few inches lower than the base of the stove. The conduit itself is about level (more or less) from the back of the stove to the exterior wall. This is the adaptor I'm using:

(broken link removed to http://rockymountainstove.com/search.aspx?find=90-53003)

 

[blades]

I was refering to outside air intake for stove, never seen a dryer set up that way either. Zenfire was refering to the outside air intake should be lower than the floor of the fire box/pot perferably not on the windy side of the home. I set the out side portion up so it goes down then loops up and loops down a bit again - seems to keep any wayward wind from creating a suction on the intake. Others have done similar but inside up and down a basement wall before exiting to the outside. added benifit of this is the intake air gets a bit of tempering before introduced to the stove. Used to do the same thing as a fresh air source into the return line of the furnace but a lot longer with a filter box in the line as well- before the fancy HRV units came along for home owners.

 

[WoodyIsGoody]

Zenfire was refering to the outside air intake should be lower than the floor of the fire box/pot perferably not on the windy side of the home.

The windward side is preferable to the leeward side if you're not going to have a split, pressure balancing intake setup (which is the only way I would consider an outside air intake). Because Tuesday's windward side of the house becomes Wednesday's leeward side.

There is no significant "tempering" of the outside air without a heat exchanger. That's another negative of outside air intakes. If the clothes dryer or other exhaust fan is operating when I'm ready to light a fire, I either crack a window on the windward side of the house (if it's windy) or turn the fan off when I'm ready to light the fire. The best tempering of intake air is by using room air to feed the stove. This increases the efficiency of the burn, especially on secondary burn type stoves.

 

[fbelec]

Also since you are having this issue make sure you have a working carbon monoxide detector