Originally posted elsewhere, moving this to a new thread: I was planning to install my OAK earlier in the fall and never got around to it. Well, I'm back to it - hoping to get it installed this weekend. I ordered an exhaust adapter to reduce from 2.75" Harman flange to 2.5", and also ordered a 2.5" 6 foot flex pipe. The high level plan is to attach and run the flex pipe up into the same 8" SS fireplace liner where my 4" exhaust flue already runs. I will simply move the 4" flue gently to the side, making enough room to run the 2.5" OAK right along side it, just a couple of feet up. I will also attach some aluminum screen to the end of the OAK flex pipe with a hose clamp, to keep out any debris that might somehow make it into the 8" liner. I know, it should never ever happen, but better safe than sorry. I need to insulate the entrance to the 8" SS liner, all around the flue and OAK pipes so fresh air can only come from the outside and not from in the house, and also so no cold air will come directly into the house. Here's where I'm stuck: I can't find roxul / mineral wool / high temp insulation to save my life. Yes, they have it at Lowes and Home Depot, but only in car sized quantities. I only need a little bit, and can't stomach the thought of paying $45 for a massive bail when I only need 5% of it. I have called every hardware store and stove shop in the area and either they don't sell it, tell me they will get back to me when the stove repair guy gets back with the van (which they never do), or want to charge the same price as Lowes or HD, only for a single serving size! This is just insanity, of all the things to get caught up on? I have thought about using plain old pink fiberglass insulation because it's real easy to come by small quantities. It's one of those topics that triggers strong sentiments though. One person will tell you it's absolutely fine, another will tell you it will light on fire and your house will burn down the first time you light the stove. I just can't win here. Can I get some advice on this? Does anyone know where I can buy a small quantity of mineral wool for a reasonable price? Last but not least (promise). The idea of running the OAK pipe up the 8" SS liner infers that I will have free air flow coming down from the top. I have read in several places "just drill a couple holes up at the top to let the fresh air in". OK, I get the concept but I'm not exactly comfortable doing it. The 8" SS liner extends up about 2 feet past the roof line, so I have plenty of face area to drill holes. The Harman manual says the OAK air intake should be at least 12 inches from the exhaust flue. Fine, I will drill the hole(s) at least 12" down from where the 4" exhaust flue exits the 8" liner. Questions: The air-intake hole in the stove itself (behind the flapper) is only about an inch diameter. How many holes should I drill at the top? 1, 2, 4? What size? 1 inch? Half inch? Do I need to cover the hole(s) with screen to stop the wasps and hornets making their way in as soon as warm weather returns? Assuming I do, is there a "clean" way to put screen over the holes I just drilled in the SS liner? Do I just cut a makeshift piece of aluminum screen from a roll and apply it over the holes using high temp silicon or self tapping screws? Seems shoddy and I don't know how long it would last anyway. I also read that drilling holes may not even be necessary because there could already be sufficient air flow without them. I suppose this suggests the possible presence of air leaks in the flue that shouldn't be there, and I really don't think that applies to me, nor do I want to potentially starve the stove of fresh air by assuming there is already sufficient fresh air flow when there really isn't. Am I making a mountain out of a mole hill or what?
Exhaust parts arrived today. Amazed at how well the exhaust adapter fits over the air intake flange on the stove. Perfect fit!
hopefully all those parts are Stainless (or aluminum)? Intakes get cold, and can get copious amounts of condensation in fall and spring, depending upon relative humidity.......it'll be a rusty mess if it isn't
Flex pipe is aluminum and adapter is aluminized finish. Still no joy finding roxul. I'm making a last ditch attemp to find some at a stove shop on my way home tonight. FYI I'm planning to drill two or three 1" holes at the top and cover them with 1" round screened aluminum vents - found some on Aubuchons website. Will take pictures of everything along the way.
ask around for Mineral Wool.....its pretty available, 2'x4' sheets (2" thick), about $10.29/sheet.....its not at all uncommon
At long last, the OAK is installed. Will be using the next few weeks burning experience to determine if it has made a noticeable impact. Will post pictures this weekend.
I can't wait to hear the results. Been thinking on doing this with mine although it won't be too feasible until I relocate it the entire 12 feet I'm moving it when the roof goes on this winter....
A week after installing the OAK I found smoke in the hopper this morning. First time that's ever happened. For now, the OAK is disconnected until I figure out what's going on. Should have known something was up, the flame pattern was doing that bizarre harmonic strobe light effect that sometimes happens, only it burned like that all night. Usually that condition, whatever it is, only happens briefly then goes away. I'm guessing the stove was starved for oxygen. Seems odd that this would occur a week after the OAK install, where up until last night it was burning like a champ. Wondering if the outside temp had something to do with it, because it was warmer last night than any other night since the OAK was installed. The other factor is until last night I was burning the PTL softies, but last night I switched to the FSUs that leave the big nasty clinker (and yes it happened again). Something else I noticed after disconnecting the OAK - When the stove is off, there is no air flow in or out through the OAK pipe. When the stove is running, there is a noticeable draw of air going into the OAK pipe (up the chimney). I'm assuming the heat from the 4" exhaust flue is creating a strong draw up, so this means when the OAK is attached to the stove, it is fighting the natural air flow, pulling the heated air back down into the stove. Also when the OAK is attached, the pipe gets pretty hot, which isn't a surprise - from everything I had read, that is one of the benefits of running the OAK this way, because it pre-heats the combustion air, like the Selkirk DT system does. It's getting hotter than I thought it would, though. Lastly, I smell smoke faintly when the stove is lighting or at the tail end of the shut down sequence, and I can sometimes see a faint wisp of it if I look really closely. This part is not new, it has always done this since the stove was installed. It's more noticeable now though since I stuffed insulation into the 8" SS liner to stop air freely going up / down it, as part of the OAK install. I'm pretty sure the smoke leak is in the T-cap itself. I think the bottom of the cap is perforated and that's where the smoke comes from until a good strong draw is established up the flue. I don't know why the T-cap would be perforated, is that traditional? It is practically resting on the floor of the fireplace so it is impossible to see or get at it without disconnecting the venting from the stove. Ugh...I'm done thinking about it for now, it's time to relax.
So the OAK has air coming in when disconnected? While the stove is running? It should. Because the stove is exhausting 80 CFM of air, it will take the path of least resistance. Which is the open end of the OAK. As for smoke in the hopper? The only rezoning I can think of, is the embers/pellets were not completely burnt upon shutdown. And because the OAK is attached, it allowed the intake flapper to open when the wind blew (slightly pressurizing the intake and opening the flapper door) When the wind blows, it will tend to blow through the intake, and can come through the air wash (making a "smell). Most stoves shutdown long enough to allow all embers to extinguish. But maybe there was a hot clinker, or something else that caused the pot to have embers.
No, it's the other way around. When the stove is running and the OAK is disconnected, there is a strong pull OUT. The OAK is sharing the same cavity as the 4" exhaust flue (both run inside the same 8" SS liner), so it gets real warm in there. I suspect the heat in the cavity from the 4" exhaust flue is creating a strong draft UP / OUT. So when I connect the OAK to the stove, the combustion fan is actually fighting that draft (apparently?) and pulling the heated / warm air into the stove for combustion. I guess if nothing else, this tells me all these years when I didn't have any insulation at the entry to the 8" SS liner, and I thought I didn't need any - it seems like I could very well have been losing a lot of heat up that thing after all. The smoke was present in the hopper while the stove was still running! This was not at shut down time. I just opened the lid to see what the pellet level looked like, and low and behold there was smoke in there. A decent amount too, that was freaky.
