Alright, I'm back after a few days of experimentation with some info I'd like to share, both to update the crew here, but also in hopes to level the learning curve a bit for anybody else who decides to buy this stove, especially if they've never owned anything like this before.
I called DS Stoves (Heco) mid-last week to talk about the difficulty I was having keeping the stove cool. The gentleman I talked to was clearly speaking as candidly as he could without opening himself or the company up to any kind of liability, and he was cautious not to go against anything the manual said. He did say some things that were reassuring, though, and insightful to how the manual was written. First, he confirmed that the stovetop temp should be measured over the left cookplate, which is directly above the firebox, and is also directly exposed to secondary flame a lot of the time. The reason for this he said was simply because prolonged exposures to temperatures over 800 are going to run the risk of warping. He mentioned that Heco actually stocks extra left cook top panels for cases where customers accidentally warp them from over heating. Reassuringly, he did say that approaching and even exceeding this temperature for brief durations should be expected when using wood, since wood puts off a lot of heat when it's gassing. He said you just don't want it over 800 consistently, for "hours on end".
Next, I asked him about engaging the oven side of the stove to keep the stove top temp down and more evenly distribute the heat within the entire stove. Here, again, he sided with the manual's recommendation to keep the oven off when you're only using the stove to heat. In support of this stance he said two things specifically, "The oven isn't built to the same spec as the firebox", and "When you engage the oven, you have to worry about fly ash getting to that side of the stove".
So, after the conversation, I got thinking about what he means when he says the oven side of the stove isn't built to the same spec as the firebox side. Taking the cook plates off the stove, it's pretty clear what he means. Obviously the firebox is lined completely with firebrick. The oven side is by-majority exposed metal. Here's where his comment about fly ash is especially important -- fly ash comes from coal (not wood), and it quickly causes rust if it's not cleaned out. My suspicion is that DS Stoves holds a blanket recommendation to run these stoves with the oven side off in case the user is burning coal, because it's unlikely that the user going to clean out the space around the oven often enough to prevent a premature rust issue if they're burning coal.
Another point of support for opening the oven side of the stove when burning wood is that the entire left side of the oven is protected by the same baffle material that the top side of the firebox is. The entire air channel all the way down the left side of the oven is protected from exposure to direct flame (unlike the underside of the left cook top).
Probably the biggest point of support for opening the oven side when burning wood is that the whole dang thing just works right when you're circulating the air around the oven. A 650-degree stove top with the oven engaged puts off much more heat than a 650-degree stove top when the oven is not engaged. Go figure.
I did install a second stove pipe damper over the weekend, and even with both dampers completely shut down, I was unable to keep the secondary flames from lapping right up against the bottom of the left cook plate when the oven was not engaged, sending it over 800 degrees. This might not be so bad with small loads of wood, frequently reloaded, but who wants to have to reload their stove every 90 minutes or so?
I have since been running the stove almost entirely with the oven engaged. The only exceptions to this are when I'm getting a new fire started, and when I'm getting new logs burning after a reload. The reason for this is that I have found that engaging the oven is about equivalent in draft reduction to shutting down a pipe damper when the oven is not engaged. When running the stove with the oven engaged, I've been able to load up the firebox on a hot bed of coals, and keep the stove top temps under 800 for the entire duration of burn. There's usually a spike in temps early on as I'm getting the new logs going, but once I engage the oven side of the stove, stove top temps tend to stay between 550 and 700, depending on how much fresh wood I've loaded in.
The stove burns very cleanly. I've had overnight burns of 6-8 hours, and I've yet to truly fill the firebox. I've probably maxed at 70% full, or so, so far. I've experimented with the bi-metal regulator, but I haven't been using it for regular burning when I'm around the house. I've found that if I try to use it to get fresh logs started that it doesn't respond quickly enough to the rate at which the logs (and stove) get hot. Consequently, the fire is allowed to "run away" until finally, the bi-metal regulator shuts down the primary air. At this point, the fire smolders down until the bi-metal regulator finally opens up again. I've seen the stove "cough" a few times in my experimentation, once the primary air finally opens up again and all the smoke in the stove tries to ignite at once.
I think the best use of the bi metal regulator might be for situations where you've got new logs on the fire, and the stove is calming down, but you're not sure the secondary air on its own will keep the logs going. If you don't want to sit and babysit the stove, you can wind the bi-metal regulator temp to whatever temperature the stove is currently burning at, and if it starts to go out, the primary will open up to keep it from smoldering while you're gone.
I keep the secondary air wide open all of the time. The only exception is if I'm going to bed and the logs are basically burned off, I might back the secondary off to 50% or so to avoid burning the embers out too quickly.
I'll also say that the stove is very, very easy to clean. You pop the 3-piece top off, and you can remove the firebox baffles, and clean the top and sides of the oven air circulation passages. There's a hatch beneath the oven to open to let you clean the air passage underneath. There's also a hatch at the exhaust to clean that chamber, as well. If creosote builds up in the stove, the design of the stove will not make clearing it any more difficult than it has to be.
So, there it is. Those of you that recommended running the oven side of the stove with wood fuel were correct in my evaluation.
Thank you, all! I hope this thread is helpful to future cook stove buyers.
