arch stack placement

[parsissn]

I just bought some equipment and included is an arch with the stack going horizontal straight out the back of the arch instead of the top. It goes out the back, through the wall to a cleanout box then goes vertical. Does anyone else have an arch like this? Right off I can't think of an issue as you are really just extending the path of the exhaust before it turns vertical. I suppose you may loose some efficiency since you aren't making the exhaust turn as soon and thus allowing it to maintain speed a bit longer. If it turned vertical sooner it may slow the flow down just a bit and allow some of the heat to stay on the flue pan a bit more? Just wanted to see if others had seen or used a similar setup and get your input.

Mark