Shutting damper makes flu temp rise

[rudysmallfry]

I was just wondering if this is normal. Last year, when I switched to double wall pipe, I decided to add a damper to my setup. I was very limited to where in line I could put the damper, so it ended up being 6" up from the stove rather than the 18" I wanted. I've noticed, whenever I shut it down even a 1/4, the flu temp tends to rise. It does seem to give me more heat output from the stove too, but it's not fulfilling it's function of giving me piece of mind when I get a fire going too strongly. I thought the affect of using it would be to get the fire burning more slowly and bring the temp down, not up.

 

[English BoB]

Unless you tamper down your air supply into the stove your fire will not slow down. By cutting the air intake and closing the damper you are restricting the fire to the stove.
When you need more heat / fire open the damper and increase air supply.

bob

 

[KimiBwoah]

Is your thermometer/temp reading before or after the damper?

 

[rudysmallfry]

After. It's 18" up.

 

[jpowell1979]

Guessing you have a rather tall chimney. Draft is pulling more air than needed. With the damper closed it is still getting enough air but the air is moving slower and getting hotter. Kind of like how your cars defroster blows hotter when the fan speed is lower. With the double wall you will lose less heat and have a greater draft out the top. Does your stove have any controls on the intake?

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[rudysmallfry]

The stove just has the air control which, with these newer stoves, doesn't completely shut down the air. My chimney is 18' with 2 elbows. It's just about right for the stove. On the warmer days, it's just enough height to give me draft. On the really cold nights, I have to be very careful on reload to not allow any new air to the coals or else I have to sit there for awhile waiting for a runaway fire. One night it climbed all the way to 800 before finally backing down. It was technically still in the safe zone for double wall, but I was not amused.

 

[kraco14]

I had this same problem and started a thread about it a week or so ago. I was getting extremely high flue temps and the key damper didn't seem to help at all. I've been experimenting with it for the past week. I have found that, on reloads, if I keep the damper closed about a 1/4 turn and start shutting down the air much sooner than I was previously doing, my flue temps are significantly lower but my stove top reaches the desired temps. The key damper has actually helped get the stove top up in temps faster.

I really have to be 2 steps ahead when shutting down the air. If I do it right, the fire almost looks like it is going to go out each time I step it down. I can barely see flame on the wood. I noticed the same thing that you are seeing. If I shut down the air like I was doing previously and then closed the damper, my flue temps would sky rocket.

 

[rudysmallfry]

That's good to know. I have been keeping the air very low on a reload but opening the damper back to full each time. I'll try keeping the damper at 1/4 next time out and see what happens. Thanks.