Considering running OAK up flue?

This is a copy from the 'old' site...

XXarth.com/talk/threads/oak-drama.94214/page-4#post-1477265

Not sure if the pics work (fb is blocked at work anyway so i don't know if they are dead links or not for real)

 

Why does Harman have 3" diameter fresh air intake flanges on all their insert frames? Is that because Harman determined that 3" diameter flex is adequate? ? ?

 

yup....tho its not recommended to pull the air more than 8' or so thru flex piping, although admittedly I would be hard-pressed to prove that to you.....best way would be to test the draft on a cold appliance with and without a long intake pipe......

 

Interesting because on one install my chimney man installed the 3" flex up 30 feet and it was not connected while I had the Accentra Air Adapter on order.
The cold air was just falling down that 3" flex and blowing out! So when connected to the stove it worked perfectly and no difference with it off. The proof is in the pudding. I tried it and it works perfect!

BTW, where did you see it was not recommended to run flex farther than 8' for intake air?
How valid was that source?

My source for running 3" flex when going more that 6' is from England Stove Works which is a very good source.

 

well, like I said, draft data....empirical data, actual readings, would be more useful than opinions here as to how the draft "felt". As for my source, mentioned above that I'd be hard pressed to prove it to you...but can you show me in writing that its ok? (other than someone's say-so?) I think you'll be similarly hard pressed. I can show you though, in the Harman literature (see below):

http://downloads.hearthnhome.com/installManuals/ACC52i_I.pdf (see figure 4.1...its on page 10)

now, note that the intake pipe DOES NOT go to the cap? Why might that be? I challenge you to find for me somewhere in the install manual where that intake pipe goes to the surface. As we all know, as a UL listed appliance, the only approved way to go about an install is to follow the directions for that specific model (NFPA211). Deviations from that (including "fabbed" non-UL rated parts) are NOT technically correct, and if, God help us, a disaster were to occur with the stove (fire, CO poisoning), who do you think would be on the hook? I believe it will be the installation in which the install manual was not followed. Refusal to follow the instructions can negate the UL rating for the unit.
As for what someone at Englander SAYS, their opinion really isn't valid on any units other than Englander. You cant take the instructions from one unit and assume its "OK" for another.
Draft data would be handy, because it would show us if there is in fact a difference between using short versus long pipe. So, in lieu of that, I choose to follow the directions as written and tested rather than, well, guess, that its ok. I might not find it in writing that 8' is the max, but how about the picture in figure 4.1? Now, SHOW me your instructions....

I guess we're gonna have to agree to disagree on this one, Don.

 

Hello

Yes, we do disagree but the manufacturers or someone should have better guide lines for us to follow! I understand you must go by Harman.

From the Harman Manual
"#1 Installing into an existing fireplace chimney This method provides excellent venting with 100% outside air which is the most efficient operation of this unit. This method also provides natural draft in the event of a power failure. A4” stainless steel flex pipe is needed for the flue pipe, and 3" aluminum or Stainless Steel Flex Pipe is used for the intake."

I can just bearly see the outside air flex in the diagram going above the blocking plate! No limitation on length.
Boy is that vague! ! !

Here is what is what is in the Englander 25EP insert manual

From the Englander manual
"Outside combustion air must be connected, either by running the outside air
duct down through the ash clean-out of the fireplace, OR by running the
outside air duct to the top of the chimney."

"Increase the outside air pipe size to 3.0 in. diameter pipe if the outside air
connection is more than 6 ft. in length, more than two (2) elbows are used
or if the stove is installed in a basement."

The ash cleanout is not a very good option. It is not permanent unless you cut or replace the cleanout cover. Altering a chimney in a home is probably against the fire codes. Also many chimney cleanouts are inside the home which would not provide outside air!

There is also no limitation on length. That is why we go to the top, there are no chimney alterations.

 

well, the manufacturer certainly cant cover any and all situations we tend to see in the field in their manual, although they try their best.

Might also be important to note that the 52i is a 52,000 btu/hr output stove, whereas the 25EP is less than half of that, requiring half the air for combustion as well.....still need to follow the manual for each unit. So, if 3" pipe is adequate for a 25k btu/hr stove, whats necessary for a 50k+ btu/hr stove?

The Englander 25EP manual also states:
Long runs of pipe and excessive elbows for outside air should be
avoided. Due to frictional resistance in pipe, any excessive outside air
piping can result in poor stove performance.
(but does not state how much is too much)

Also, doesn't the Englander manual specifically state that:
"Do not mix and match components from different pipe manufacturers when
assembling your venting system (i.e. Do NOT use venting pipe from one
manufacturer and a thimble from another)."
So, given that, "fabbed" caps also would not be allowed as per the manual as well? Interesting indeed.

 

We do not used fabbed caps they certified caps that come in the liner kits made by Olympia Chimney. The biggest chimney wholesaler around.
No it does not say anything about what type of venting to use. Yes it is true they BTU is half but our setup has been proven to work for 50k units too.

 

Hello
It still seems strange to me how the Harman manual talks about air restriction in a long flex pipe when there is a flapper valve in the inlet pipe on the stove that is a huge air restriction since it never fully opens? ? ?

 

Actually, it does fully open, unless, of course, intake air or exhaust air is restricted, or your combustion fan is dying.......and it's the Englander manual which mentions restriction.....

 

Hello
I just pushed the flapper in as far as it will go on my Harman Advance and it hits the back wall before it is fully open or fully vertical?
See

 

It's fully open when it goes to the back wall....can't go any further

 

I guess we disagree here because it looks to me there is still some restriction.
Also having a 90 Deg bend in the air intake plenum is more restrictive than the Englander 25-EPI that goes straight thru to the burn pot!

 

Rather than argue design in a UL listed unit, why not simply follow the directions? Deviating from them to save time or money really never will pay off, and only exposes you to risk. At least in following directions and doing things as specified, you're covered from a liability standpoint. It all "works great" until it doesn't. That's where it gets expensive. Sometimes it's even a better idea to walk away...

 

I agree. You have to go by the book . It just seems there is a lot of differences in how manufactures think outside air should be handled for a FPI. There needs to be more testing and some commonly agreed on methods and some common parts!

 

For the record, my manual says it can run a short run with block off plate (ie, after damper, use chimney air if cap is not air tight) or run all the way up.

In the past, my stove would soot up real easily and end up overflowing the burn pot if i ran on high for longer than a few hours.... not enough air to go with that fuel.
Since i've had the oak, i've not had that issue. it burns more complete.

I'd say that's as scientific as I need it to be.

 

Thanks for your input Briansol. The best method is what works!

 

yea, only problem is that we, as service folks....and don't be shocked here, guys......don't always know what the issue is! Sometimes have to try different things, rely on experience, the owner telling da truth on what they've done to/with the unit, etc. Why is my stove not feeding? Why is it sooting up? Why am I not getting heat?.....and the list goes on. Thing is, on the phone, we cant always tell what's wrong or fix your unit.....house calls aren't free either...sometimes the unit simply should be scrapped or replaced rather than fixed....but we don't know that until we see it. I hate selling parts to folks who have no idea what's wrong....throwing parts at a unit to save a service call...and end up spending more. Some folks, many here, are great at the technical side of fixing their unit, but that's MAYBE one person in 50....
Our biggest issue at this time of year is getting to these folks....only so many qualified techs, and so much time in the day.....its a challenge till like January, when things seem to be more manageable. I can send a kid out to your place to look at your stove, but he (likely) wont be able to fix it....do you want THAT, or rather wait for a tech who is factory trained, and with some experience?
As for installs...is the guy installing the stove:
1. Licensed? (you'll wish he were if the building dept. is involved)
2. Have workmen's comp? (you'll wish he did if he falls off your roof)
3. Liability insurance (you'll wish he were if you have a calamity due to his work)
4. Factory trained? (on the fence on this one...I've seen some real dopes get factory trained and be no better when they get back)
5. Do they have parts in stock? (Can they fix it THAT day, or do you have to wait a week or two for a re-visit with parts?)

Don and I might not agree on some stuff above, but I am guessing he would agree with this, and probably be able to add more to it.....

 

Yes LW I do agree, Also how do you tell people that the pellets that were left around all summer in a damp room are so full of moisture that you cannot start the stove even manually with gobs of starting gel! It is not the stove here! No kidding, the customer's house was very cold and when I tried to start the Harman Accentra FS manually it steamed up the inside of the door glass with moisture! ! ! Unless you have a kiln to dry these pellets, they are no good!