Hi, thanks for offering to do this. There's so little hard information available that I'm really just listing thoughts that have occurred to me while reading other people's speculations.
But my questions do center on the burn-profile that Woodstock is aiming to provide with the new stove. I’m still not clear just what this is, or how the addition of the secondary burn changes or improves it from what, say, a larger Fireview might offer.
Here’s a quote from daleeper, from late last year, talking about Blaze Kings. that crystallizes a number of my interests in the Progress:
“The ability to control when you want to use those BTU’s are where the BK stoves shine. A combination of thermostatic control, cat, and large firebox are unique to the BK stoves, and those that own them will tell you that the burn times are not bs. Those that don’t own one can’t seem to grasp that concept. There is no magic, and no need to open the window when the stove is running too hot either, because you have more control over that stove with the thermostatic control.â€
For me (not for everyone), this is pretty close to ideal. The key notion here is
control: the ability 1) to spread out the available btus over the desired burn time, and 2) to reliably control the quality of the burn (high or low) with the available damper settings.
So with those priorities in mind, these are some of my specific questions:
1. burn profile. 80,000 btus is nice, but sounds like a peak output that couldn’t be sustained for long. I’d be more interested in Woodstock's version of what Blaze King calls its real-world results: the “average†range of btus we can expect to see over a full burn-cycle, over a decent (10-12 hour) burn time.
2. specific expectable burn time. 16 hours sounds good. And other Woodstock owners suggest that their figures can be believed. But can they be more specific? How long could we expect the stove to go, damped down and with a full load of decent hardwood, maintaining a surface temperature of 300 or greater?
3. does the introduction of the secondary burn element increase the risk of run-away fires? That seems to be one disadvantage of non-cat stoves: it can be tricky to get the air mixture right when burning high enough to engage secondary combustion.
4. what is the current thinking about thermostat options? Todd posted from an email he received from Woodstock:
"One of our suppliers now makes a damper operator that runs on a couple of thermocouples and looks interesting. It could close a damper to prevent over-firing, or it could open a damper to prevent oxygen starvation. It looks interesting. Separately, we developed an algorithm that controlled a damper and a fan to pressurize the secondary air and was driven primarily by an O2 sensor. We have applied to EPA for an SBIR grant for a related project. One of these last two is more likely the direction we will go in."
These all sound great--any idea when one or the other might be available? And what difference in stove operation would they expect it to make?
5. control of burn at low air settings. One of the trademark advantages of cat stoves. Todd's email also included the information that
"the new stove has a “butterfly†damper: the butterfly has very good control of the burn rate at low firing rates."
This degree of "control" sounds great. Could they elaborate on how exactly it works? Is there similar control at higher burn rates?
6. related question about over-heating. Blaze King and Fireview owners often report being able to control the heat output so that, even with a full load, the stove can be kept from blasting you out of the room. From the Blaze King manual:
Many new woodstove users hesitate to load enough wood to sustain a fire, fearing that a full woodstove automatically means a hot fire. The combustion air control, set at the lowest air control setting, permits a low fire even with the firebox full. . . . The stove can be FULLY loaded without increasing the heat output. The fire will simply burn longer.
This again sounds like an extremely desirable level of control: to be able to load all the way up and not necessarily get burned out of the room. Can the Progress do this?
7. how the two burn technologies work together. Here's what the post in the blog says:
"at a medium burn rate, the secondary flames and catalytic combustor alternate depending on the conditions in the firebox."
Do they really "alternate"--i.e. switch back and forth? Or do they cooperate, so that both are functioning at the same time, and it's possible that some smoke might be captured by the secondary air and some, at more or less the same time, by the combustor?
8. trade-offs. What, if any, compromises the two systems have to make in order to work well together. The blog says:
"the Progress will automatically deliver unused secondary air to the combustor at lower burn rates, or allow the air to combine with gases in the firebox at higher burn rates for a spectacular secondary burn."
Is delivering unused secondary air to the combustor going to reduce the efficiency of the combustor at low settings? Or is it just what you want to help the combustor deal with all the smoke that's being generated during a smoulder?
Thanks again for offering a medium for those of us who can't make the party! Hope you have fun and learn a lot in the process.
Lots and lots of pics from all angles! Did I mention pics :ahhh:
