90 degree or straight?

[Sweber]

Setting up a new rig (2x6) it's going to be a pain in the *** to poke a hole through the roof on the slope for a straight pipe. In the past I've always used 2, 90 degree bends in the pipe to the outside wall. No problem with draw. The logs practically were sucked out of my hands. What's the verdict straight or are the bends o.k.?

[Fred Henderson]

I vote for a straight run.

[brookledge]

I'd go straight up but if you say you have used 2 90s and been satisfied then do it that way. You can always re do it later if it doesn't work as good as you like it to
You can get roof jacks made for your pitch.
Keith

[Haynes Forest Products]

I say if the draw is fine and the hole is there why not use it. Bends only slow down the draw and sometimes thats a good thing. Are we not always talking about dampners to keep the heat in the arch.

[mtnmeadowmplfarm]

I know with wood furnaces it is often better to use two 45 degree fittings to lessen the creosote buildup in the pipe, not sure if the same would apply. I would normally say to go with a straight run though to increase your draft. Dampers are for wood stoves.

[Russell Lampron]

Get a roof jack and go with a straight pipe. The evaporator will like it better.

[Dan W]

I understand the idea of good draft, but what if you had a blower. There really isn't any natural draft. Couldn't you just speed up the blower for more air? I too am thinking about two 90's with a blower. It would really simplify things.

[Fred Henderson]

I think about how hot those elbows get and any build up in them.

[Grade "A"]

I have two 90s in my stove pipe but I burn oil. I have never had a draft problem. I would say that 45s would work better. With the amount of heat (flames in some cases) that goes up the stack I don't think you would have much creosote build up.

[red maples]

hey steve.

you got yourself a new rig thats great. what did you get? new or used?

I know your concern is the metal roof. So check with the manufacturer that made the roof and see what they have for hot stack roof flashing...they usually have have some thing that fits easily to the that companies style of metal roof. and are usually pretty easy to install. and the hole is really not that bad...but Like others have said if 2 90's work don't worry about it as long as its long enough it shouldn't be problem. It wasn't in the past? right!!

Just make sure you get the right size because alot of them are sized for insulated pipe. which is usually 2 inched bigger than noninsulated.

Good luck with that new rig.

[3rdgen.maple]

Red kinda touched on my opinion on this one. Personally I would go straight up but if you are against it I would increase the stack diameter and put your elbows in. I think with the larger stack it will help with your draft. Thing is you might think that it works just fine but you may never know that it could be better unless you went up.

[Sweber]

A couple more things. It's a 10" stack, stainless,12 ft long. Not worried about creosote build-up, runs way too hot for that. Not putting in a blower....this year. I there any hard data to show a straight stack draws better?

[red maples]

yes I agree. but if it works well you wouldn't even think it could work bettter. ya know. and if its not neccessary then why bother.

I don't know if I would go bigger pipe size I just mean that when you go through the roof or wall or whatever asa far as fire code is concerned it is usually required that you use insulated pipe so when you order what you need like my stack is 8 inch dia. so the roof flashing opening is 10 in dia. because I have to follow the fire code which requires an insulated pipe.

Is that what you ment? I think I might be confused!!!

I bought my rig from sweber, so I know his set up from when we took it apart. and we talked about his roof.

[3rdgen.maple]

Sweber good question? Not that I have heard of. I figure that since draft is a key and since stack height is a key that any bends in the pipe will restrict it. What size evaporator are you running? I assume 2x6 since you have a 12 foot stack. If so 10 inch should be plenty. Elbows are cheap if you are concerned about the hole put them in. Maybe add another section of pipe to help it out a little bit more.

[KenWP]

When you instal a gas line you have to take into consideration the 90 and 45 degree angles to get enough gas to what ever your useing so I would say a bend in a smoke stack would have to be considered as a restriction also. I had a so called plumber intasll the gas lines to the NG generator and it would not hardley start and I showed him the spec book and he agrued with me but finally put in 2 inch line because of the bends and with a bigger orfice in the regulator it would start under load fianlly.