Venting and Setting Up a Gas Roaster

[SJM]

Peter made me to it 

Seriously, I need to know what I need to know about venting a roaster (the Hottop and also the Huky).

I am going to set both roasters up in a previous rental unit.  Previously I have hauled the Hottop outside onto the deck, but that is an impediment to just getting with a roast, and I'd like to have everything set up in a secure and safe location.

What I am most curious about is how it can go wrong:  whether venting can impede the fan action for example.

Truth is I don't yet know enough to ask my questions very astutely, so I will take whatever potshots come my way.

Susan

[jspain]

Thanks Susan for starting the thread! I've had a few folks ask the same question surrounding the venting and install for my new 1.5K. I'll be posting pics in a few weeks of the whole process.

I'm going with double walled metal pipe out the wall with a cap on top of the chimney. Dedicated 220 line and propane tank several feet away in another room of the "Man Cave." Gas line through the wall to the roaster. I have no code to pass here but I want to be safe!!

The Sono is now vented out the window with single wall flex metal. It works fine and I just open the window, put the pipe out, and roast away. Works fine for my application.

Several folks have used hood vents with your machines. 

[SJM]

Okay, so no one is chiming in on the issue that I am concerned about which is the possibility that the vent itself could be a hindrance to the ability of the fan to exhaust the roaster. 

Not to be worried about? 
Just give the air and smoke exiting the roaster a path to the great outdoors?

[ecc]

The diameter of the pipe is important, but depends on a few factors.  Any exhaust ducting will increase the resistance to air movement, and decrease overall air flow a little from the roaster.  Any bends will also restrict airflow, and the total distance of exhaust pipe is also a factor.

Generally, the bigger the roaster, the more bends you have, the longer the pipe you have, the bigger the inside diameter has to be. 

There are additional concerns, like how much junk a flexible vs. smooth vent will trap, how much the outside of it heats up, and what would happen if the chaff and dust inside caught fire.  You also should make sure it is pretty airtight, and maybe invest in an inexpensive CO detector to have nearby just in case you leak some of the combustion byproducts into your airspace.   

An additional big concern to me would be any storage of propane in an enclosed area.  Propane tanks are designed to vent directly out the fitting when they warm up, which would include after any heavy use.  This almost guarantees propane inside your house.  This is also a huge safety issue in the event of a fire.  Most local codes prohibit any storage of propane inside. 

[Cammie]

I'm not sure this adds to the discussion or not but here's how my Torrefattore is vented:





I think the question of whether the vent itself could be a hindrance to the ability of the fan to exhaust the roaster would depend on the particular roaster being vented, the type of venting materials that are selected and the set-up/placement of the venting. But, I'm not very mechanical so I could be totally wrong.

I'm going to play with a Huky for a few months before I make my purchasing decision regarding a bigger gas roaster (Susan is a bad influence...really bad and an enabler too ).  My brother-in-law will be setting up the Huky.  I'm pretty sure he'll place the propane tank outside the shed.  He is very safety minded.  I will post pictures of the venting once the roaster is set-up.

[SJM]

Hey !!!!
    
Who's the enabler here??

So, if I put the propane tank outside the cottage, I'm guessing that attaching and unattaching it is an invitation to leakage, so it probably needs a long hose through the wall???

[peter]

You could find a more technical answer, but...  you don't want the exhaust so small that it's restrictive (and every elbow increases restriction), nor do you want it too large.  I always thought a long horizontal run would be undesirable,a long run - maybe 25' w/ an elbow - and doesn't appear to have any problems.  He uses, as do I, a simple 4" duct pipe - mine came from HD.  My roaster came with some thick/sturdy single-walled pipes that fit together with clamps, and if I was setting things up permanently I'd probably use it. 

I have two 4" pipes coming off the roaster, one from the drum exhaust blower that originally did airflow and cooling duty, the other of the two pipes from the cooling blower I added at Milo's suggestion so that I/we can cool faster while letting the drum blower concentrate on drum airflow for the next batch.  The drum blower exhausts from the roaster to a chaff collector, and then both 4" pipes go vertical for 3' to a plywood baffle which I put in place of the basement window, and remove after the roasting's done.  Takes a minute to set up, and a minute to take down.

My exhaust pipes, both from the drum and cooling tray, never get all that hot.  The chaff collector may have a lot to do w/ that.  I'll get my IR thermometer on both pipes next time I roast.  I'm sure many double-wall venting pipes are there because of local codes, and the codes are theoretically there because of safety reasons, and a larger commercial roaster no doubt puts out more heat than mine, but I've never seen the reason for going that route.  If I was running a long stack up through a building, maybe between walls, I might see the wisdom of using it; for what I do and what most of us do, double-wall is a waste of money.

The plywood baffle I mentioned fits the window opening perfectly, and has two 4" pipes mounted in it, both about 2' long mounted horizontally.  I've never had an instance where a northerly wind was so strong that it affected roasting or the exhaust.  The worst that could happen, and again I've never experienced it, would be that the airflow through the drum would be diminished, and that's not such a big deal if it did in fact happen for a moment now and then; it would be much the same as having the airflow to the drum closed, which we do at times during the roast anyway.

[SJM]

Excellent information, Peter, Thank you.
I will look forward to the pictures.

This is the space where I am planning on setting up the roasters.
The wall to the right has a very shallow overhang.  The wall to the left where the big window is opens onto a deep deck, so venting there looks good but probably isn't...

 

[peter]

An overhang probably isn't much of a consideration, as you can see by Cammie's vent.

Chaff may be something to think about if you vent over your deck.

Edit: Photos added to my previous post.

[SJM]

 I run my cyclone directly behind the roaster connected with a 10" length of stainless steel flex pipe. Exactly the same as you'd find an auto parts store for car exhaust. It's pretty rigid and I like how it looks. It's bridging a 3" gap and it's snug enough that I don't need hose clamps. I'll add a pic later today just for grins.

Okay, tell me more about  a "cyclone"?  I think I get that it's a gizmo to de-chaff the roast, but the term has just recently arrived in my mental inbox and I'd like to know more about it/them.  Is it something I need to make myself?  Is it something I will add later if the Huky seems to need it or ? 

Susan
looking forward to pictures which speak at least 2000 words in my language

[peter]

Similar to a saw dust collecting cyclone;

http://www.woodcraft.com/Product/2021015/26326/Oneida-DIY-Molded-Dust-Deputy-Cyclone.aspx

I would think that the little heat our roasters are putting out, the above model would work fine.  And if you life in CA, with wide open spaces, you might not even care where the chaff goes.  Whether or not you collect the chaff will have no effect on the roasts you produce.

[SJM]

Thanks, Peter, that looks supremely reasonable. 

Given how much time I spent yesterday just vacuuming the floor, ceilings, windows, etc. in that cottage I can't help but wonder if they sell a whole-house model?

[SJM]

Here's a video of a test of three dust separators:

https://www.youtube.com/watch?feature=player_embedded&v=dBqXmwzbVXI

[Tourman]

Great thread and conversation - thanks to all for bringing it up and contributing. My vested interest is one who is 1) getting a 1# natural gas sample roaster from the USRC group buy and 2) intending to get my city code official's approval.

It sounds like we have many who haven't pursued code approval and I pass no judgement on your choice. But I, like B|Java, want coverage if something bad happens...I don't want my insurer rejecting my claim because I had an "illegal" operation going in my basement. (Not talking about moonshine or meth  )

I think code-approved use of "commercial" roasting units in a residential (non-commercial) application is still cutting edge or plowing new ground. At least, that's the way it sounds to me as I talk to my city code people or others in larger cities who've gone through this. That's at least mostly true if you're venting directly out of your house, not up a chimney. If you are operating a business and not in your home, you're likely using a large(r) roaster and venting is pretty straightforward and certainly more costly. My code official is willing to work with me to get the job done achieving what we both want (safety) and what I prefer (least cost, not the big-buck Mercedes options). To get that approval they are looking for proof that what I propose is safe.

For clarity I'm going to define what the options look like, most already directly or indirectly referred to in this thread already, from cheapest to priciest:
1. First, there are all the cheap routes that are probably not good choices - plastic dryer ducting, etc..
2. Next there is single-wall rigid and flexible galvanized steel or stainless.
3. There is what is called Type-B flue venting. It's double-walled, rigid galvanized steel - some have an aluminum liner, but has an air space between the walls for insulation. It will remain hot to the touch so it needs 1” clearance (air space) to any combustible materials like floor joists, etc. The cost is reasonable as compared to...
4. Finally there is Class A venting that comes in double or triple walled stainless pipe. This is the Mercedes, costly route. It's lined with some sort of thermal woven material. It's what Steve Green notes most manufacturers recommend -- if they say anything -- to keep their legal butts covered. (Bill Kennedy at San Franciscan told me they "recommend" this - referring to this one http://bit.ly/WTjsBH).

I'm hoping to use #3 Type B. I know that code officials like to talk about/look for UL listings for appliances and materials - it's the safe haven for them. Type B typically says "Use for venting listed natural gas or liquid propane Category I, draft hood appliances, or appliances that have been specifically tested and listed to use Type B Gas Vent. The appliances listed typically use Type B Gas Vent systems, but not always: Furnaces, Water Heaters, Boilers, Room Heaters, Decorative Gas Appliances, and Unit Heaters." USRC is quick to point out that their roasters "are not appliances" - which has definitional meaning to them, is lost on me, but not lost on my code people.

Having said all of that, has anyone had code approval of your home install for a natural gas roaster? I'd like to know what you used. That's especially the case if it's direct vented outside (not chimney) and Type B. If I can get pics and a referral so my code peeps can talk to your code peeps, I'll be a happy camper! 

[peter]

You may want to call your insurance agent and ask for their thoughts too.  I wouldn't suggest doing anything unsafe or something that goes against your own common sense, but I talked to mine and they said I'd be covered if my house burned down, simply because it's an accidental loss.  They insure against loss, even loss that's facilitated by stoopidity.  It would be the same as in the case where I do some wiring w/o pulling a permit, and the wiring not being code, caused a fire.  They wouldn't disallow the claim.

This isn't to say we are encouraged to be hillbillies and jerry-rig things haphazardly.  I just think it would be good to check w/ your insurance agent.

We're talking about low temps on the exhaust.  To my way of thinking, it isn't the temp of the pipe that's the problem, or to put it another way, whether that pipe will get hot enough to combust surrounding materials.  The double and triple wall pipe may be insurance that if there is a chaff fire, that the fire will not spread.  If that's true, then it's a primary concern to keep the pipes clean, rather than be lulled into a false sense of security that a super-duper code-approved venting system might give.