Can't control air intake on PE T5 after chimney work?

[phoenixheater]

We've had a pretty good season since the Alderlea T5 was installed in November (thanks again to all who helped with the decision.) But we had a strange and scary problem today after having some work done on the chimney, and haven't been able to figure it out.

Anyone have any thoughts on what might cause the air control to suddenly not be effective in damping the fire down? Here's what happened...

For the past couple weeks, I was having a few concerns about the stove and install: whether we had enough draft, whether the chimney was full of junk already, etc. I was hearing that "raining" sound in the chimney, and it seemed to me we were getting too much smoke in the house when opening the door. So we decided to get another chimney company in to show us how to clean and take a look to see if all was OK.

For context, our set up was that we had 6 inch stove pipe coming straight up from the stove, a 90 degree elbow to exit the outer wall, and then double wall pipe up approximately 30 feet (past the 2nd floor and attic, and above the steeply pitched roof. So, a pretty tall chimney.)

When the guys came Tuesday they ID'd three problems with the install. 1) They said we would get better draft if we have a more gentle slope from the stove to the wall exit, rather than the sharp 90 degree turn. (See picture of how it looks after their mod.) 2) The T-bracket on the outside had the cleaning cap stuck on funny. 3) There was single wall pipe wrapped in insulation going through the exterior wall, rather than double wall. (Ouch -- this last seems to be a serious code violation and dangerous! We're working on getting restitution from the installers for that repair.)

So, they came today to fix these three things. We built a small paper and kindling fire in the stove, they verified that smoke was going up and out the chimney, and left. Five minutes later, we had added a couple of very small logs, no where near filling up the stove, and the room started filling with smoke, apparently from the new stove pipe and silicone offgassing. This was way more smoke than the offgassing when we first installed the stove.

We tried to cool down the fire by shutting down the air control. The fire didn't go down. We watched, and it kept blazing. The stove pipe appeared to get very hot, and the wall behind it got hot. We called the guys to come back, used the fire extinguisher on it, and tried but couldn't figure it out. They decided the wanted to come back Saturday to replace the length of double wall pipe that had a slight bend in the mouth, which he had sealed with silicone. But he said this was unlikely to be the problem, because it would have been hot inside the wall if heat were escaping there, and it wasn't. It was cool, although the room-side surface of the wall was hot.

They moved the stove a couple of inches back and forth while working on it, but otherwise didn't touch it, so I can't see how the air control mechanism could have been damaged.

The installer's theory: The air control "flap" is a flimsy little piece of metal. The new, straighter chimney caused such an excessive draft that it "sucked" it out of position. He plans to recreate the 90 degree bend chimney when he comes back on Saturday to address this.

My husband's theory: There's some leak in one of the many joins on the pipe between the stove and the wall. Air is being sucked in, creating turbulence, and causing the pipe to become a secondary firebox. (Hence the high heat.) Installer says this is impossible.

Does anyone have any ideas, or thoughts on these theories?

Many thanks! We love the T5 and are anxious to begin running it (safely) again.

 

[begreen]

Unfortunately, it sounds like you have a bunch of half-experts for installers and repair guys. You don't use silicone on woodstove connector pipe. Get that gunk off of there. And definitely get that thimble done correctly asap!

With 30 feet of pipe exterior, plus another ~5ft interior, I suspect that this is simply a case of very strong draft. My guess is that the wonky cleanout cap was masking the issue by leaking air. Once this was sealed up, the draft improved dramatically. Switching to the 45 on the stove just made it stronger. It's sucking the fire right out of the firebox. I'd return to the original setup with the 90 elbow and would add a butterfly damper to the connector pipe about 2 ft above the stove. This will give you greater draft control during cold weather and windy days.

PS: What is the distance between the top of the elbow going into the thimble and the ceiling?

 

[phoenixheater]

Thanks very much, Be Green -- this makes sense. We definitely had not enough draft before, but probably some problem with the initial install caused this. We'll go back to the 90 degree elbow.

I went and measured...we've got 16 inches from the single wall pipe to the ceiling. It's supposed to be 18, isn't it?

 

[begreen]

Yes, 18" is correct. I suspect that the ceiling sheetrock may be getting hot. You can mitigate this with a heat shield attached to the pipe. Or go to double wall pipe to reduce the clearance to 6".

 

[crazy_dan]

Yes, 18" is correct. I suspect that the ceiling sheetrock may be getting hot. You can mitigate this with a heat shield attached to the pipe. Or go to double wall pipe to reduce the clearance to 6".

oh man there you go making his already over drafting stove have more draft lol on a serious note begreen is correct.

 

[madison]

cpl of things, i can't see in the picture as it is a little dark, but the new angled connection to the stove looks suspect, if it is a straight connection jammed/angled onto the stove, all I can say is, well I'll with hold comments regarding the new installers.

The single wall must be changed to dbl wall if it is that close to the ceiling including the elbow. The Class A that transitions thru your thimble (fyi, they make Class A in black) looks like it may not protude enough into the house, measured from the thimble to the end of the class A for proper code (I forget but I think it is at least 9").

Suggestions as above, use dbl wall dvl telescoping both horizontally and vertically above your stove. Have a slight rise from the elbow to the class A-not exactly horizontal. This will allow you to put your stove exactly where you wish it to reside on your hearth (maintaining wall clearances which look sorta close in the back of the stove). Black Class A to transition the thimble/wall! Don't build a fire until it is fixed!

 

[begreen]

Yes, double-wall connector pipe would give the cleanest looking installation with safe clearances. The Alderleas stay pretty cool on their backside. With single-wall, the T5 requires 12" from the back wall, 7" with double-wall connector pipe. Perhaps an alternative to changing the pipe to double-wall would be to put a section of sheet of metal or durock on 1" spacers on the ceiling. Effectively, a ventilated wall shield on the ceiling.

 

[BrotherBart]

Perhaps an alternative to changing the pipe to double-wall would be to put a section of sheet of metal or durock on 1" spacers on the ceiling. Effectively, a ventilated wall shield on the ceiling.

Would that really work since the wall shield works because cooling air is convected up through it from bottom to top for cooling. Not so sure that would work flat mounted on a ceiling. The heat would just radiate through the shield right on up to the ceiling.

 

[begreen]

You could be correct. I was thinking back to when Elk installed the donor stove in a place with low ceilings. In that case the ceiling shield was approved by the inspector. In this case, given that the pipe is 16" away from the ceiling, I think a ceiling shield would be effective as long as it was open on all sides, similar to a mantle shield. But maybe not. It would be easy to test with an IR thermometer.

 

[phoenixheater]

Thanks for the catch on the ceiling, Be Green, and to all for the advice.

We were planning on putting a metal heat shield on the ceiling. It sounds like there are some doubts about whether this will work? This is because the heat shield is designed to be cooled by convection and thus must be vertical?

The installers told us that they were reluctant to use double wall inside because of unsupported weight and difficulty cleaning. Does this make sense? I'm assuming that if we went with double wall for the horizontal section we would also need it for the elbow? Or would that be considered curving away fast enough to meet 18"?

We'll check into the protrusion issue. Anyone know if there's someplace on the internet we can find a complete code list and go line by line through it with these guys when they come back?

This whole thing with the installers has been incredibly frustrating. Our neighbor offered to do it, but I insisted we go with "professionals" due to the whole burning down the house thing. Some professionals!

Thanks much for all the advice.

 

[begreen]

More nonsense. If the system is triple-screwed at every joint there doesn't appear to have a support issue. Double wall should be no harder to clean. It will probably require a telescoping length to make it fit just right. Can you post a front view of the stove and flue so that we can be sure?

If you do go with double-wall connector pipe, it will need to be all double-wall from the thimble to the stove. Remember to add the manual damper section. I still think the ceiling shield would work well, but that's my own opinion. You should do what you are totally comfortable with.

 

[madison]

Hogwash! It would be no different to brush the inside of double wall pipe vs single wall.

Insist on double wall from stove to Class A, and you will not need the unsightly shield on your ceiling. I would think that shield would have to have an air gap as well to be safe and to code.

 

[phoenixheater]

Hi everyone....We're still debating on the double wall pipe vs ceiling shield solutions. I'm leaning to the double wall as the safest and best looking, but my husband has raised some concerns about the double wall prospect:

1) Will we have significantly less heat gain into the living space because of the well insulated pipe?

2) Could this make our excessive draft problem worse, by keeping the flue gases significantly hotter?

Thanks for any thoughts...

 

[begreen]

Hi everyone....We're still debating on the double wall pipe vs ceiling shield solutions. I'm leaning to the double wall as the safest and best looking, but my husband has raised some concerns about the double wall prospect:

1) Will we have significantly less heat gain into the living space because of the well insulated pipe?

No, this is not a lot of pipe. Let the stove do the job of heating the house.

2) Could this make our excessive draft problem worse, by keeping the flue gases significantly hotter?

Yes, this may increase draft. Reread the recommendations to add a draft damper so that you have control over this. They make them for double-wall pipe. In fall/spring when outside temps are moderate you may run with the damper open. In cold weather, you might start with the damper open, then once the fire is going strong, close the flue damper to moderate the draft.

 

[phoenixheater]

Hi BeGreen,

Thanks for the advice on the pipe. That was my thinking on the heat issue, too.

In terms of the damper...We called our PE dealer and he told us, in the strongest possible terms, under no circumstances, to install an inline damper. He said it would "utterly mess things up".

So now I'm torn. It sounds like a good idea to me. And I know you've got lots of experience with this stove. But he's the guy who's s'posed to know, right? So we're back to don't know...

If anyone has a knowledgable PE dealer they can recommend we speak to, I'd go that route.

Thanks!

 

[begreen]

If I recall, the original issue of this post was to that the stove was hard to control due to increased draft. What does the dealer propose as a solution? An inline damper will not utterly mess up anything. There are some folks that can't run their stoves without one. It will put a greater responsibility on the person tending the fire to judge the appropriate level of dampening to achieve a good burn rate. This comes with a bit of experience, but it's not hard.

Some people just set the damper at halfway (handle at 45 degrees) and leave it there. I prefer to pay closer attention to how the fire is burning. Draft conditions will vary with the weather and temperature differential between indoors and outdoors. This is not a big deal. At worse, you might forget that it's closed on some spring day and wonder why there is some smoke spilling out the front of the stove when you open the door. Opening up the flue damper will clear up the problem quickly. After a season of burning the routine becomes habit, just like working a bypass damper in a stove. FWIW, I've had dampers on four of the six stoves I've owned.

PM thechimneysweep here on the forum. Tom is a long time PE dealer and will tell it like it is. He has some info in the sweep's library as well:
(broken link removed to http://www.chimneysweeponline.com/hoxdraft.htm)