Never anticipated this...

[Fred61]

My EKO 25 has had a weak flame and low flue temperature for the last week or so. Has been taking longer than the normal 3 to 4 hours to bring storage up to temperature on my daily burn. I knew enough not to fiddle with the air settings that have not been touched for the last 7 years but I suspected something was plugged or out of adjustment.
I decided to tear into it this morning and give it a good cleaning and as soon as I pulled the hatch the problem was staring me in the face.
The bypass flap (damper) is bolted on loose and secured with a nut and jam nut so that it wobbles in order to mate with the opening and seal all the way around. Somehow that bolt had tightened so that the two surfaces did not seal flat to each other and there was a leak most of the way around. It was basically only touching a one point.
Although I wouldn't consider it fun, it was a fairly easy fix once I found my wrenches.

 

[Fred61]

Interesting that if you leave the bypass open the stack temperature rises. Low temp reading in this situation tells me that most the combustion air was going through the proper channels and the air that was leaking must have been going across the top of the fire and not contributing to combustion.

 

[leaddog]

Interesting that if you leave the bypass open the stack temperature rises. Low temp reading in this situation tells me that most the combustion air was going through the proper channels and the air that was leaking must have been going across the top of the fire and not contributing to combustion.

I think what was happening was you were losing pressure in the upper chamber so less gas was being forced down. It was closed enough so the primary and secondary air was going to the right places ,just not getting gas to burn
leaddog

 

[Fred61]

Could be. I assumed the leaking air was diluting the exhaust air therefore lowering the stack temperature.

 

[BoiledOver]

Concerning the loose fitting bypass damper: I cleaned the damper mating surfaces of the Eko25 two times early on. Each time after cleaning, it caused a creosote buildup which made for difficult opening of the bypass for a period of a dozen or so burns. The creosote acted as an adhesive to glue the damper shut. I have not experienced the situation which Fred has described, but will now keep an eye out for a tightening nut.

 

[Fred61]

That's why I posted this occurrence which seemed trivial. To give others a "heads up." Not all problems originate with wet wood and air settings.

Perhaps your glueing of the damper occurred because after cleaning (scraping) you had a larger surface in contact and therefore was more difficult to release. If your boiler idles you're going to accumulate creosote on all surfaces of the upper chamber including the joint on the damper.