Need advice on straightening flex pipe during chimney liner install

I'll soon be installing my new Jotul F600 CB woodstove. I'm using a 6" ss flex liner in my 13"x18" tile flue on a 17' run down the chimney. The stove company where I bought my stove and chimney liner kit sells its flex pipe off a large spool. Both ends of the pipe were pretty ragged, so I cleaned them up fairly well using a utility knife and hacksaw. While working on the ends of the pipe I could tell this flex liner is pretty stiff. It is currently in a circle with a 5' diameter. I know I'll need to send it down my flue as straight as possible and I'm wondering if anyone can chime in with some advice on the best way to accomplish this. It seems it would be unwieldy to straighten it out on the ground and then try to carry a 20' long piece up on the roof. I sure can't see myself somehow getting that long a piece vertical in order to slide down the flue! I've watched some YouTube videos and they seem to be unspooling the flex pipe as they feed it down the chimney, but this stuff I have is way to stiff to do that as smoothly as the video shows.

Straighten it as best as you can on the ground, or even on the roof if the roof is not too steep to do so safely.
It will bend while you are trying to slip it down the chimney. No biggie, just straighten it as best you can as you work it down the chimney. It is never going to be perfectly straight, but it will be plenty straight enough to operate as it should. One thing you can try is once it is in place, have someone hold the bottom, or tie it off, and gently pull up on it from up top to straighten it out from the force of the pulling. Don't pull too hard as you might cause it to unravel. You probably won't need to try and pull to straighten it though.
Another tip: If it gets hung up on the way down, spin it and it will slip past whatever is hanging it up. Usually a glob of mortar between the old clay tiles.
It is awkward but with the size of your flue, it should go down pretty easily.
You can also buy or fab a cone to screw into the end that will be going down, tie a rope off the to cone, and have someone pull on the rope and you work/push the liner down.
If you have a good amount of extra liner, you can also cut a vertical slit in it and make a cone out of the end part you slit. Tie rope onto something large enough that it won't pull through the cone hole, and screw the end into a cone shape after you have the object with rope tied onto it, resting inside the cone.

2 people is great, 3 people is awesome. The liner will squirm around on the roof as you have another person on the bottom pulling it down with a nose cone attached to the liner, the 3rd person hanging out on the peak keeping it in line for the person feeding it down the chimney is a great help, or so I hear, always done it it with 2 people.

Nick:

Yes it is possible to install the flex pipe yourself with the help of a friend, or your significant other. My wife helped me insulate and slide a 25 foot flex pipe down a 13 inch by 13 inch terra-cotta flue. I do recommend that you insulate your flex pipe first. You can buy 1/2 inch insulation kits on-line for this purpose. It's much harder to insulate after the fact.

With the help of a second person, straighten the pipe on the ground as much as it is possible to do so. Apply the insulation and metal mesh. If your roof slope is not too steep, (ours is 4/12) you can slide the pipe down the flue by yourself, slowly spinning the pipe as necessary to get it down the flue.

To get the pipe on my roof, I started at the bottom of my ladder, then had my wife hand me one end of the pipe while I ascended the ladder, pulling the pipe upward. When I got to the top of the ladder, I stepped onto the roof with the pipe resting against the ladder. I then pulled the 25 feet of insulated pipe and placed it against the brick chimney to keep it from rolling off the roof. Then I picked up the "down end" of the pipe (there is a marked up/down orientation to the pipe - at least on mine there was), and started to slide the down end into the flue. I should mention that I had taped a 30 foot length of rope to the down end, which I threw down the flue first.

Then my wife moved to inside the house and started to gently pull the rope down the flue opening, while I was feeding (spinning) the pipe down the chimney. Within one hour we had the pipe in place.

Good luck with your pipe install.

I'm getting ready to do the same. This helped me -

Good idea on the rope too to lightly tug from the bottom

I have a shed roof so I carried the whole thing still in the shrink wrap it came in up to the roof and straightened it as best I could there. It was like wraslin' a gator at times but I got it down the pipe without too much trouble. Did it by myself but a second set of hands would have been helpful. I did mine without a liner so if you are going to line it you will probably need to get it straight on the ground to get the liner around it. Took awhile for the whole project but it was fun and satisfying to do it myself.

Mine is 40' and there is no way I was going to handle that on the roof, so I unrolled it in the house and dropped a rope down the chimney and pulled it up with someone pushing it up from the bottom. Be prepared for an upper body workout.

I ended up putting the liner down my chimney on my own and it went smoothly. I only had a 20' liner to deal with. I unrolled it on my deck as much as I could and then positioned it so that the end with my T- connector (minus the horizontal piece of pipe) was sticking up a few feet at the bottom of one of the valleys of my roof. Once I was up on the roof I dragged the liner up to my chimney and fed it down my 13" x 18" clay flue liner straightening it out as much as possible as I went. I was fortunate that when I cut my fireplace damper out it gave me a straight shot into my fireplace opening. When the liner got down to the hole I cut in the damper it got hung up and missed the hole, but I was able to reach it easily from inside my fireplace when I went down to the living room. I had pre-built a support the same height as the flue collar on my stove, so once I got the liner through the hole in the damper plate and through the hole in my stop off plate the bottom of the the T - connector sat right in place.

I was a little concerned that my liner was going to end up leaning on the sides of my clay tile liner, but once I connected the T - connector to my stove I was able to pull the slack out from the top of my chimney when I put on my top plate and when I looked down the liner it looked pretty straight with just a mild helix like rotation from the way the ss liner is constructed. It didn't appear to be touching the clay liner anywhere. However, when I went down to the fireplace to see how things looked I could see I pulled too hard on the liner and my T - connector was being pulled up into the fireplace at a slight angle. Another trip up to the roof to loosen my connection on the top plate and release about an inch of slack lined things up perfectly.

If I were doing it myself, I'd rig a hand crank winch (think boat trailer) to a platform across top of chimney, and draw it up from below. This is actually how one installer proposed doing one of mine, to avoid removing my heavy slate chimney topper. Working on a roof with something a unwieldy as a chimney liner sucks.