we have a chimney angled at less than 45, and the fp does not draw well...however, our fireplace is over 100 years old...i would think that todays new fireplaces are a much better design...speak to some experts at fireplace stores, i would not rely on your designer...

emmachas,
30 degrees is the max.
brix

I had given up on a response! Thank you both so much. My designer suggested the angle to solve a placement problem. But, if it doesn't draw well, we would never use it.
brix, will a 30% angle draw as well as a straight chimney? There are a lot of beautiful fireplaces in expensive homes that don't work. Takes a really good brick mason to get it right!

emmachas,
no, any angle will not draw as efficient as a straight line. I have built quite a few fireplaces from scratch, but they were all planned ahead of time rather than trying to make something work. I am not clear on why you need a sidewall for support. A chimney/fireplace is self supporting.
brix

brix, I so much appreciate you sharing your knowledge and experience! You have saved me from an irreversible mistake. On our plans, the designer had placed the fireplace in the middle of a one story 'connector' between 2, 2-story sections of the house. He planned for the chimney to angle 45% in the attic so that it (the chimney) could sit next to the 2 story wall which is 5' to the left of the center of the fireplace. (I'm having a hard time explaining this. In my mind, I still can't see how it would look.) I understood him to say, the chimney could not extend to the necessary height unless it were to be moved to the 2 story wall.
Anyway, It's easy to draw pretty things on a piece of paper. The fireplace would have looked awesome where he placed it. But, building it's another story. You're the expert. He's moving the fireplace.
Thanks again for taking the time to help me.

The max limit is 30 degrees, as stated---but that is in US. If you are in Canada, I believe the max limit is 45 degrees there. If that makes any difference at this point.

Lookin, thanks for taking the time to respond. We're in the US. My main concern is that the fireplace draws well. We lived for 16 years with one that didn't. I don't want to run the risk of having another one. Our plans are not yet finished so moving it is only a minor problem. Thanks again for your help.

http://www.woodheat.org/technology/bpfireplaces.htm

Here is link to "Best Practices" article.

There are many factors that affect how well a chimney will draw Size of firebox to size of flue liner , height of chimney flue , properly built smokeshelf, opening size of fireplace facing ,downdrafts caused by taller structures or tall trees near the chimney, etc . I have built many chimneys with slight angles in the flue liner, in fact with a 2 story house that has a fireplace on each floor and only one chimney the smoke chamber has to be corbelled over enough to to bring the bottom fireplace flue far enough over for clearance for the upstairs fireplace, It does sound a little funny that the designer would want to bring the flue over that much in order to "support it" any angling should be done within the internal structure of the chimney. Having said that we have corbelled chimneys over inside the attic before but only by a small amount and only as a last resort.
Cheers
Martin

Get make/model of unit...go to the manufacturer's website and check their on-line manuals. They will show what venting options are available for that particular model. An improperly installed unit can void your home insurance.

I was under the impresion that this was supposed to be a "masonry, wood burning fireplace" if so it would be constructed on site.
Cheers
Martin

Many, many thanks to all of you for your expert help.
Brickman, you are right. We want a masonry fireplace with a brick chimney. The designer was told that's what we want. His preliminary drawing had the 45% angled chimney. After posting the question on this forum, found out he had substituted another type of chimney (pipe?,stucco?) without discussing it with us because, "Brick chimneys are not what you want. You can buy a Lexus for the cost of two brick chimneys." Futile to point out the Lexus depreciates the minute you drive it off the lot while two well constructed masonry fireplaces with brick chimneys don't. Anyway, at least in our part of the country, the Lexus cost more.
Hopefully, we will survive this design phase to actually build the house!