I don't use a permanent connection as you should zero the manometer before each use. You could simply drill a small hole in the stovepipe and use a very small hose barb if you want, the tapered pipe thread should pick up the thin sheet metal and seat well.
OK.......Here's a photo of the plastic tubing & the barbed fitting I assume is to be used to connect to the stove pipe. I have drilled a small hole in the elbow at the wall thimble. Do I just stick the barbed end of the brass fitting into the hole & somehow connect the tubing to it?? (intuitively it would appear that the tubing should slip onto the barbed end of the fitting & that the threaded (larger) end should go into the stove pipe....But I'd don't want to put that large a hole in the stove pipe)
This is where my Head Injury really gets in my way, so please accept my apologies for being dumb!
You're only going to use one hose, the other is not relevent for what we are doing. Plugging the hole... you could use a pipe plug the same size as the hose barb has, more than likely 1/4" NPT, about $.25 @ the hardware store.
Either one will give you a good reading, it just changes the direction the fluid travels from zero. Most of us use the plus scale (to the right) as it is defined better. If it goes to the left, simply change which port you are using at the top of the manometer. I'll look at mine when I get home and post which one it is as I forgot. Oh yeah, make sure you have the same hose at each end, that siamese thingy can bite you. The tubing is silicone, not plastic so it won't melt.
Or, you can use a piece of tubing, I used a piece of brake line, which is about 3/16" OD. Cut the flared ends off the tubing. Slip the supplied hose over one end of the tubing, put the other end through a screw hole in a flue pipe joint.. the other end of the hose to the manometer.. make sure the fluid is moving to the right side, with the expanded scale..
OK...I've got the stove up & running & the manometer moved .03 (3 lines) but to the left? (Last night, Greg had me try getting a draft going with a hair dryer which moved the meter to about .02 but to the right. ) I know I can reverse the connection to the other port on the manometer & am thinking last night I may have gotten a "blowing across a coke bottle" effect & may have caused air to be drawn out of the stove pipe rather than in it.
Questions: 1.Does it make any difference which way the gauge moves? (left or right) as long as the fluid is still showing & not blown out of sight to left? (very little room on the left forf the fluid to move) 2. With a very light load (1/3rd full) & fairly warm outside (low 60's to mid 50's) I know the draft is not going to be real strong....so...does a reading of .03 on the manometer provide any useful info?