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I’m not sure what you mean when you ask “can you partially block the return of the ERV as a test”?

Please see screenshot attached for window and vent locations. I’m not certain which direction the winds are generally coming from — but we have tried fires in calm as well as windy days and that doesn’t make a difference. I’ve also tried with the ERV on and off, as well as we had HVAC guys hook up a fan to the exterior vents to blow extra air in through:
1. The exterior ERV intake
2. Outside air intake to the fireplace
3. Chimney air kit

The only one that made a slight improvement (but still smoked) was when it was blowing directly in the outside air intake.

I wonder why the manufacturer would suggest an open top cap when that would just allow rain and snow to pour right in (I never even thought about the rust!) It would maybe be okay if there was an open top and then a “roof” above that, but not sure if there is such a thing, or if that would even make a difference. Uggghhhh.

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I mean take a piece of cardboard or paper or something, and partially cover the vent that is "sucking in" air to the ERV. Tape it in place temporarily. This should make the air pressure inside the room higher. If it fixes the smoking issue, then your ERV needs to be adjusted.
 
I’m not sure what you mean when you ask “can you partially block the return of the ERV as a test”?

Please see screenshot attached for window and vent locations. I’m not certain which direction the winds are generally coming from — but we have tried fires in calm as well as windy days and that doesn’t make a difference. I’ve also tried with the ERV on and off, as well as we had HVAC guys hook up a fan to the exterior vents to blow extra air in through:
1. The exterior ERV intake
2. Outside air intake to the fireplace
3. Chimney air kit

The only one that made a slight improvement (but still smoked) was when it was blowing directly in the outside air intake.

I wonder why the manufacturer would suggest an open top cap when that would just allow rain and snow to pour right in (I never even thought about the rust!) It would maybe be okay if there was an open top and then a “roof” above that, but not sure if there is such a thing, or if that would even make a difference. Uggghhhh.

View attachment 315841
That picture is helpful. Just a guess, but it still sounds like an imbalanced or undersized ERV system. Is this diagram roughly correct for the ERV layout? If so, it makes sense that the far window would not help. The ERV return is sucking the air in that area.

IMG_7863.png
Do you know what brand and model ERV was installed? Do you know the sizes of the supply and return ducts in the system?
 
That open top TVK cap is meant to be installed under a shroud which you do not have so I wouldn't install that. I think in your case you definitely need more than the minimum chimney height though it's hard to say if that alone would resolve the issue. If you go higher with the chimney it's going to need roof brackets installed.
 
Thank you all for the suggestions. Last night we used a camera to look down the air intake vent — as far as we could tell there’s no blockages. It’s however a bit difficult to see it clearly as the flashlight on the head reflects the silver walls of it.

I’ve attached a photo of the interior to show the location of the windows in relation to the fireplace. Last night I did a test to see what would happen with the fireplace opening made smaller. As you can see in the photo, I put fire-rated gypsum board on either side to reduce the width from 42” to 34” and then I also tried to 30”. Both of these dimensions allowed me (for the first time) to close the nearby window, but as soon as I’d close that far window it would again instantly start smoking.

There’s also 2 small windows on either side of the fireplace I’ve never tried opening while burning a fire.

I’ve requested the model, make and duct size of the ERV so I’ll keep you posted. Also, good idea to try taping off the ERV exhaust; I will try that next fire.

Do you think installing one of these exterior air supply ventilators would be worthwhile?
https://www.condar.com/ASV.html

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Taping off the ERV exhaust might damage the motor. Instead, try turning its breaker off and see how the fire burns then. It still may take opening one of the small windows an inch. Experiment and see how it behaves.
 
Hi everyone! We’ve still had no luck in solving this problem. I’m attaching two photos of a test I did to see how much it’s drawing. I took toilet tissue pulled apart to just 1 ply (so it’s very lightweight), and taped to the front of the fireplace.

Even with two windows open, this is as much as the tissue gets drawn into the fireplace. I don’t know if this is normal, or a very little amount? I have nothing to compare it to, as I’ve never had a fireplace before.

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Typically the most draw would be at the bottom of the fire. Yes, that still looks awful weak even in that position. I do not know how the exhaust path looks in that unit. In my stove due to the air wash for the glass which blows down at that apx spot I would likely see the same thing.
 
Did you try the suggestion in post #81? What were the results?
 
Thanks again for your suggestions.

Okay, maybe I should try the tissue again, but much longer so it hangs lower, towards the bottom half of the fireplace.

Yes, I did turn the ERV completely off, and not much difference. we went back and forth a few times between the ERV on & off, and it seemed if anything it worked better with it off - but not a drastic difference. And either way we need to have the far window open as well as a window near the fireplace.

Surprisingly, when the tissue was taped there, I experimented with the outside air intake lever both open & closed, and that air intake makes no difference to how much the tissue moved.

This is so frustrating not having any idea how to resolve this. I wonder if I should experiment with blocking off the chimney air kit from the outside (since this is only required in Canada and isn’t installed on the majority of these units). Could that be causing some sort of a problem?

What’s all of your thoughts on this idea?:
The only other thing I can see trying is to extend the height of the chimney even further. Unfortunately, that would mean we’d need to add supports, and that’s a lot of work and damage to drilling through the roof shingles etc if it doesn’t even solve the problem. With that said, I wonder if the installer could extend the chimney temporarily (?) — just long enough to hang around while we light a fire to “test“ if the extension makes a difference. And if not, he can just remove that extension and put it back to how it was. Does this sound like a silly suggestion for me to make?

Thanks again to all of you!
 
Yes to both ideas
 
Thanks again for your suggestions.

Okay, maybe I should try the tissue again, but much longer so it hangs lower, towards the bottom half of the fireplace.

Yes, I did turn the ERV completely off, and not much difference. we went back and forth a few times between the ERV on & off, and it seemed if anything it worked better with it off - but not a drastic difference. And either way we need to have the far window open as well as a window near the fireplace.

Surprisingly, when the tissue was taped there, I experimented with the outside air intake lever both open & closed, and that air intake makes no difference to how much the tissue moved.

This is so frustrating not having any idea how to resolve this. I wonder if I should experiment with blocking off the chimney air kit from the outside (since this is only required in Canada and isn’t installed on the majority of these units). Could that be causing some sort of a problem?

What’s all of your thoughts on this idea?:
The only other thing I can see trying is to extend the height of the chimney even further. Unfortunately, that would mean we’d need to add supports, and that’s a lot of work and damage to drilling through the roof shingles etc if it doesn’t even solve the problem. With that said, I wonder if the installer could extend the chimney temporarily (?) — just long enough to hang around while we light a fire to “test“ if the extension makes a difference. And if not, he can just remove that extension and put it back to how it was. Does this sound like a silly suggestion for me to make?

Thanks again to all of you!
I have a fireplace that will smoke no matter how cold it is outside if I let wood hang even an inch of the front of the grate, and that's about 1/3 of the way inside the firebox. Or to the sides, the wood will just smolder smoke and I'll see some smoke escape. Generally a hot fire with a large bed of embers and keeping my wood more toward the middle back is what keeps us from getting smoke inside the house.
 
Any back draft dampers on the OAK? Some dryer vents have one way dampers.
 
With that said, I wonder if the installer could extend the chimney temporarily (?) — just long enough to hang around while we light a fire to “test“ if the extension makes a difference. And if not, he can just remove that extension and put it back to how it was. Does this sound like a silly suggestion for me to make?
Not silly at all. For testing only, he could do this with a 4' length of single wall stove pipe or even warm air duct. Do this on a calm day with little wind.
 
The confusion continues.…. I had an HVAC expert out today, and here’s some things we figured out:

-See photo attached: Strangely, when you hold a tissue to the gap around the fireplace where the fresh air intake should be coming through it sucks the tissue to it. Shouldn’t the tissue be blown into the fireplace?

-We used a leaf blower to blow extra forced air into the outside air intake (to see if adding more forced air would help the combustion), and strangely, that blew even more smoke into the room.

-The HVAC tech confirmed the ERV was balanced. He also tried changing it to a positive air pressure, and it still smoked. Again, as mentioned before, it smokes regardless if the ERV is on or off.

-One thing that’s always confused me is why this chimney starts at 11” and then has an adapter to narrow it to 10”. I had read a few times that chimney diameter shouldn’t be narrowed?

Oh gosh…. there’s got to be something I’m missing here 🤦🏼‍♀️

IMG_8091.jpeg
 
The confusion continues.…. I had an HVAC expert out today, and here’s some things we figured out:

-See photo attached: Strangely, when you hold a tissue to the gap around the fireplace where the fresh air intake should be coming through it sucks the tissue to it. Shouldn’t the tissue be blown into the fireplace?

-We used a leaf blower to blow extra forced air into the outside air intake (to see if adding more forced air would help the combustion), and strangely, that blew even more smoke into the room.

-The HVAC tech confirmed the ERV was balanced. He also tried changing it to a positive air pressure, and it still smoked. Again, as mentioned before, it smokes regardless if the ERV is on or off.

-One thing that’s always confused me is why this chimney starts at 11” and then has an adapter to narrow it to 10”. I had read a few times that chimney diameter shouldn’t be narrowed?

Oh gosh…. there’s got to be something I’m missing here 🤦🏼‍♀️

View attachment 319719
Where does it reduce to 10”? Got a picture of it?
 
I haven’t seen this post for quite some time.
Is there a proper draft stop installed above the fireplace at ceiling level or 8’? Did the wall get insulated around the fireplace? Sorry if this has been covered already.
 
Sorry for my delayed response. I’m attaching a few photos in case that helps to answer your question. I believe the chimney air out which is right on top of the fireplace unit is where the diameter reduces.

As far as my idea to temporarily extend the chimney long enough to test if that helps; because of how high the chimney currently is, the company who we bought this from said he doesn’t know how he would temporarily extend it, because how will he get up that high . I included a photo of the exterior as well to show how high it is (ignore all of the notes on that image).

So now what 🤷🏼‍♀️

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I do wonder about adding another air intake, this time lower than before? Just a shot in the dark. So sorry you've had these issues. Best wishes.