Manometer Tube Depth

When I first hooked up my manometer I screwed a 1/4" compression fitting right to my flue. The inner cap was open to the flue. I recently read somewhere on this site about getting different readings pertaining to the length and direction of tube inside the flue. I decided to install a small piece of 1/4" rolled copper to the compression cap and direct it straight into the flue so it's closer to the center. Thoughts on this?

My personal opinion is that it shouldn't really make much difference. The concern is that air flowing by the probe could cause an inaccurate reading. The flue gases at the center of the stream and closer to the top (since the hotter gases will raise) will likely be the fastest flowing due to drag along the walls of the stove pipe.

It takes a pretty strong current of air blowing across at a perpendicular angle to see a reaction in a mano reading. At least it seemed that way to me when blowing across the end of the probe. I just don't think the flue gases move fast enough past the probe to skew the reading. Some might disagree.

I also have my probe in the center like you do.

As long as it protrudes into the stovepipe, it should not be flush.

Funny thing, I lengthened the manometer tube inside my flue this season and have been getting different readings than last season. Granted, the weather and flue cleanliness play a part. The reading is averaging about -.06 when it usually runs -.03 to -.04. Not much of a difference, but noticable. Also I cannot get my baro to limit draft well. I have the weight adjusted all the way down to -.02 and the door only begins to open when the draft is about -.06. Seasons past the baro worked flawless and kept the reading to the desired setting. I performed a full cleaning at the close of last season so there is no build up on the door or weight. The door swings freely. I can only assume by moving the probe closer to the flue center that it affected the mano reading. Perhaps my baro was always off? Ok, I'm starting to get a headache now...haha. Point is different probe depths yield different readings...imo!

Now you have my curiosity. My probe penetrates to the center of the pipe. I will slowly draw it back and see if the reading changes. I can't believe it will change that much. But, maybe I'll prove myself wrong.

I attempted watching the mano while I withdrew the probe from the center of the pipe to the edge. There was no change that I could notice.

tcalo wrote: I have the weight adjusted all the way down to -.02 and the door only begins to open when the draft is about -.06. Seasons past the baro worked flawless and kept the reading to the desired setting.

Could there be a problem with the manometer?

If you really want to play around Tom, put a 45* cut on the end of the pipe with the cut facing away from the stove.

scalabro wrote:If you really want to play around Tom, put a 45* cut on the end of the pipe with the cut facing away from the stove.

Yeah man, that might change things up a bit