Think I have a strong draft, do I need a damper?

[Sealcove]

I did some searching on this, and think I know the answer, but I am getting conflicting opinions from my stove dealer. Sorry about the length, but I wanted to provide adequate detail for consideration.

I replaced my 12 year old Jotul F600 in early Nov with a new 2021 Lopi Liberty. The new stove is running well, and I am starting to have enough experience with it to see how it performs (and learn the differences). Multiple times now, I have had fires that I feel like are not well controlled. Meaning the fire is burning hot and can't be reduced as I have limited air as much as the stove control allows. The stove top temps are flirting with over firing (800F according to the Lopi manual), and I am having to use fans to help cool the stove until the burn cools a bit on its own.

I called the dealer a few weeks back and they had the good suggestion of double checking the seals even though it is a new stove. Using the dollar bill test, the ash drawer feels fine on all sides. The main door seemed a little loose, so I adjusted the door and it is very snug now. I then experimented with different wood and I am running beech that has about 18 months and two summers of seasoning. I experimented with E/W versus N/W, and trying to use large longs for the heavy load (hoping it would slow things down). No impact, once it gets going it screams no matter what I do.

Quick notes about my stack. I had a straight pipe from the Jotul, but had to add two 45 degree bends and a short slip section for the lopi install. After that I have about 7' of ICC Double Black to the cathedral ceiling, and then 24' of Excel insulated (with 22" of it being fully outside). So roughly a 31' stack with two 45's just above the stove.

My dealer is indicating that the stove should not need a damper, but the manual states that too much draft can cause excessive burn rates/temps. I can't shorten the stack, so I am thinking my only option is a ICC damper section above the stove. Am off base and should I be considering anything else? Thanks for any guidance.

 

[Hap Shaughnessy]

I have the Lopi Endeavor NexGen and same thing here, I have 19 feet of DuraVent chimney straight up which according to manual its on the short end. 15-33 feet is their range. This is the way they were built to run by Travis Industries. I plan on installing a DuraVent damper as soon as the stove goes offline as it burns 24/7 now. If you need to speak with Travis Industries about your stove ask to speak to Benny Barber the customer service manager. Ive recently spoke with him several times and he is very knowledgeable and will explain in detail how your new NexGen operates.

 

[gthomas785]

It sounds like you are in the right direction. 31 feet is a lot of chimney.

Unless your stove dealer performed a draft measurement at the time of install (very doubtful) then they have no basis to claim that it should work fine. I would add the damper and see if it helps.

 

[Sealcove]

Thanks for these thoughts and I should add that the original chimney install was done by me and my builder closely following ICC installation and any code requirements carefully. My dealer has not had a hand in any of my stove installs. I did reach out to Lopi, but I only got very basic info back from them. They keep referring me to my dealer or vent manufacture, but my question to them is about the stoves performance with too much draft and management of that.

Unless there is an issue with the stove air control (and that seems very doubtful), the seals (will check again, but they seem 100%), then I don't know of any other options for controlling airflow. Smaller fires have not been an issue and am able to control those well, but a 75% load or higher has been an issue every time so far. I am assuming the big load just offers more time for serious draft to build and continue the burn.

I am tempted to just get the damper and see how it impacts things.

 

[Todd]

Maybe before adding a damper check and see if you can reduce the unregulated primary boost air.

 

[brenndatomu]

I am tempted to just get the damper and see how it impacts things.

I'd do it in a minute...it shocks me to read how many people just put up with what is obviously high draft...which leads to hot running stoves that are hard to control, shorter burn times, and less heat to the house.

 

[bholler]

At 31' I would have put in atleast one damper at the time of install. You may even need 2

 

[Sealcove]

I'd do it in a minute...it shocks me to read how many people just put up with what is obviously high draft...which leads to hot running stoves that are hard to control, shorter burn times, and less heat to the house.

I agree with you. I have been following a couple of dealers recommendation of not doing it, but realizing they are saying that without seeing my situation or how the stove is performing. I am certain the F600 before this would have benefited from a damper as well, though it was able to reduce the intake more (at least it seemed to perform that way until it got leaky).

I don’t want to mess with modifying the air intake of the stove, and a damper would take me 15 minutes to add in with no risk to anything. The shop only had the ICC dampers at their other location, but I paid for one today and it should be available for me to pickup in a couple of days.

 

[begreen]

Just do it. The damper is quick and easy.
It also wouldn't hurt to investigate where the stove boost air intake is. This is not the same as the primary air that is regulated by the air control. Boost air is to make starting fires easier. It's a small amount unregulated air that is aimed at the base of the fire from the front bottom center. If you are lucky, there will be a small hole in the underside of the firebox right below. This can be blocked off with a magnet, or small wad of aluminum foil for a test without any permanent modification to the stove. To investigate, pull the ash pan and use a mirror to look for a small hole front and center.

 

[Sealcove]

Just do it. The damper is quick and easy.
It also wouldn't hurt to investigate where the stove boost air intake is. This is not the same as the primary air that is regulated by the air control. Boost air is to make starting fires easier. It's a small amount unregulated air that is aimed at the base of the fire from the front bottom center. If you are lucky, there will be a small hole in the underside of the firebox right below. This can be blocked off with a magnet, or small wad of aluminum foil for a test without any permanent modification to the stove. To investigate, pull the ash pan and use a mirror to look for a small hole front and center.

Thanks, I was not aware of this. I will investigate when stove next cools off.

 

[MR. GLO]

If you install a damper watch your chimney....sometimes they add creosote...but a tiny nudge of the damper can change my draft from. 15 to .07...

A damper with a permanent draft guage is always a plus...

Have you tried turning air inlet almost all the way down and in stages? Are you getting secondary combustion for long periods without smoke?

You need good 2 -3 year old wood and covered dry otherwise it will smoke out chimney... on some stoves I was never able to turn air inlet more than 1/2...seems like the timing has a lot to do with it....

 

[DBoon]

I have a very similar situation with a Lopi Republic 1750 with two 45s and a couple feet of double wall black pipe and then 27' of double wall insulated chimney straight up inside a masonry chase. You'll need a damper. I would install a second one if I had room (I don't).

Loading east to west helps. Bigger size pieces of wood will help. Loading E-W so that primary air has a tougher time reaching the back (at least at first) helps. I don't have a flue temp thermometer, but that would probably help too to monitor the acceleration of the burn. I just stay close to the stove for the first 30 minutes on startup and turn the primary air down really early and quickly because once it runs away it is off to the races. I'd rather stall the fire early and open it up a little at a time than let it run away. It still gets hot (700-750) but not as hot and for a shorter period of time. I definitely don't leave the stove under these conditions until the stove top temps drop a lot. Luckily, the Lopi is a well made stove and it takes these temps just fine.

This year I installed the blower kit so I could push some good volume of air around it when it is getting hot. I also installed the outdoor air kit and put a damper on the primary inlet air. I haven't run the stove yet since doing this. If I was going to keep the stove beyond the year, I would probably get a blast gate on the primary air so that I could shut it down completely, if necessary.

I've looked for the secondary air inlets and I think they are underneath the jacketing, so no luck on making those a little smaller. I will look for primary boost air and see if I can find it on that stove - I don't recall seeing it anywhere when I did a thorough inspection in the fall.