Vent/Exhaust Restrictor

[Fire Bug]

Hi,
Can anyone explain to me what a internal vent or exhaust restictor is and what purpose it has on a Jotul Gas Stove,(Propane Fueled).
I see in the owners manual that it has something to do with termination height of the venting. It seems the higher the termination height the more the restrictor is to be closed.
I have a very tall chimney and the installer of my stove left the restrictor wide open,(unresticted).
Does this restrictor play any part in controling the amount of heat loss up the chimney linner to the termination point or is it just for flame adjustment purposes? Any how, mine is wide opened.
If someone can give me a detailed explanation of this device, I would greatly appreciate it to know what it is and what function it serves.
I can't seem to get a clear answer from the installing dealer.

Thanks,
Fire Bug

 

[MountainStoveGuy]

the restrictor prevents flue gas to leave the cmbustion chamber, with that you prevent heat to leave the combustion chamber. The more heat you prevent from leaving the combustion chamber the more heat comes out of the unit. To much restriction, and the unit overheats, ghosts, delayed igniton and the like. Thats why there is a chart in the owners manual to show where to set it. A proper installation follows the owners manual. The restrictor plate setting is determined by the venting graph. If the installation doenst follow the venting graph, then its not installed right. didnt we go over this a few months ago?
we did go over this:
https://www.hearth.com/econtent/index.php/forums/viewthread/6292/

 

[Fire Bug]

Hi MS Man,
Yea we did discuss this topic before but my questions where not fully answered especially the one about higher heat output from the unit with more restriction. This question has been addressed by you with your latest post.
This unit was installed by the dealers installer but he never fired up the unit because the propane company had to hook up the gas line two days after the unit was installed.
I called the dealerto send a service technician after the unit was completely installed and the gas line hooked up. He closed the air shutter slightly from its wide open position and added some ember material. When I asked him about the vent restrictor, he blew it off and said don't mess with it.
This unit is 40,000 BTU's and I feel that it is not putting out the heat it should be fore this size unit. The cast iron sides of the stove you can place your hands on and their not even warm. I do have a optional brick kit installed in the unit which I believe you said earlier, might be acting as a insalator, but I can't believe Jotul would design something like this to cut down on heat output.
The only heat comes out of the top of the unit and I doesn't seem like a whole heck of alot especially with the blower running. The rest of the heat comes from the front glass.
Like I said, the restrictor is wide open and I am thinking that I am possibly loosing most of my heat up the chimney. If this isn't the case, I am very disappointed in Jotul to produce such a poor heat producing unit. I selected them because of their reputation for quality.

Thanks once again,
Fire Bug

 

[MountainStoveGuy]

its not installed properly, it should be in positon three. If its wide open all your heat is going up the flue.

 

[BrotherBart]

What does the manual say about the the proper position for the vent restrictor for your particular flue set-up and elevation?

 

[MountainStoveGuy]

3, bb

 

[Fire Bug]

What does the manual say about the the proper position for the vent restrictor for your particular flue set-up and elevation?

Brother Bart & MS Guy.
The chart says:Up to 10'verticle and 10' horizontal (A setting Wide open), 10' to 15' verticle,(1/3 restriction "B"), 15' to 20' verticle,(2/3 restriction "C"), 20' to 40' (closed restrictor, "D", except Co Linear Vent).
They did run the flex pipe,(Co linear vent, I believe its called), up the terracotta flue.
I not sure what they mean by the "D" setting, Closed Restrictor (ecept for Co linear Vent).
All I know this unit puts out !$&@ heat for 40,000 btu's and I believe it might be going up the chimney.
I have a heat & glow FB Grand , 40,000 btu insert in my fireplace upstairs that puts the jotul Stove to shame when it comes to heat output.

Thanks,
John

 

[MountainStoveGuy]

John, i remember you had a very tall chimney. At the very least it should be C, but it looks like d would work too. I think we can pretty well establish that it should not be full open. Thats where all your heat is going. If the tech doenst know about restrictor plates, honestly you should be able to do a better job tweaking your stove. When you restrict the air coming out, you might want to open the burner shutter again.

 

[Fire Bug]

John, i remember you had a very tall chimney. At the very least it should be C, but it looks like d would work too. I think we can pretty well establish that it should not be full open. Thats where all your heat is going. If the tech doenst know about restrictor plates, honestly you should be able to do a better job tweaking your stove. When you restrict the air coming out, you might want to open the burner shutter again.

Hi MS Guy,
After I made my last post yesterday, I went over to the stove with the instruction manual and loosened the wing nut on the restrictor and closed it to the second hash mark on the manifold. It seems that there is much more heat comming from the top of the unit and the front glass. This would be the "C" Position. The stove lights perfectly and the flames are yellow not blue. There doesn't seem to be any signs of ghoasting or any other adverse effects of the adjustment.
I am going to open the air shutter all the way. This is where it is suppose to be for Propane Fuel. The tech. closed it up slightly.
Actually, the flame look better than ever and they still seem to lean back toward the manifold exhaust ports. I possibly could be closed even more.

Thanks,
John

 

[MountainStoveGuy]

fantastic!
happy heating. you should have done that months ago!

 

[jtp10181]

Be careful not to close the flue restrictor too much because one of the side effects is that it can trap more heat that the unit was tested for and overheat surrounding combustible materials like a mantle or the drywall, etc...

I once encountered a unit that had a restrictor in it that should not have had one at all, and the mantle above the fireplace got over 200 degrees (I used an infrared temperature gun). I think the tile on the face of the unit was around 250 degrees.

 

[Fire Bug]

Be careful not to close the flue restrictor too much because one of the side effects is that it can trap more heat that the unit was tested for and overheat surrounding combustible materials like a mantle or the drywall, etc...

I once encountered a unit that had a restrictor in it that should not have had one at all, and the mantle above the fireplace got over 200 degrees (I used an infrared temperature gun). I think the tile on the face of the unit was around 250 degrees.

Thanks I will keep your advice in mind. I might try closeing in more in 1/8" increments like the manual says. I don't want to close it up almost completely and turn this unit into basically a "vent free unit".
I will make small adjustments and observe the results to each adjustmetn. It still seems like there is a strong draft that pulls the flames toward the rear part of the unit where the exhaust manifold and tow ports are located.
The stove doesn't show any signs of overheating and I have no combutstibles around, behind, or above it.
Thanks,
John