Strange CAT Problem

[henkmeuzelaar]

I wonder if during a reload you raked all the coals towards the back where the cat chamber is located and pile the wood on top if it would make a difference? Those VC's have that rear chamber cat design where I could see air flow getting restricted from solid wood up against it. If there was a good pile of coals the air might have a better chance getting up through there?

Thanks for the suggestion. I tried not blocking the cat chamber float last night and this morning, and it did help, though not sure if the reason it worked better was not blocking the throat, or because there was less wood in the firebox due to leaving the space clear next to the throat! It also still took substantially longer for the CAT temp to rise substantially, as compared to a somewhat smaller load. The more I think about it, Henk's theory above really makes a lot of sense.

Thanks for the vote of confidence for one of my many theories, Gridlock, let's call it theory 2.0 (i.e. larger loads may be producing a higher proportion of water vapor at the specific point in time that you close the updraft bypass flow. This followed my (alas a bit too flippantly posited) theory 1.0 (i.e. larger loads go through a longer endothermic phase). Both 1.0 and 2.0 were generic theories, in the sense that they pretty much apply to any type of cat stove.

Then Fire God Todd spoke and made me realize that your stove is definitely not "any type of cat stove", thereby prompting me to study the online manual of your stove in order to see how much of what I had theorized about was applicable at all.

This spawned new versions of both theories; let's call them 1.1 (i.e. the longer heat-up times for larger loads might be less pronounced at the stove-top than at the catalyst top) and 2.1 (i.e. the large amounts of water vapor produced by larger loads could already deactivate the cat during the early heat-up phase), as discussed in my previous post.

Since the 1.1. version seems to resonate with the testimonies and views of several other posters who actually have an identical or similar type of stove as you have, my money is presently on the idea that with larger loads your stove top temperature may be way too optimistic and you should probably try to measure your cat top temperature more directly (or, if you do so already, at least re-calibrate the probe).

Please also remember that your stove manufacturer advises to start the cat at 450 F.....

Best of luck,

Henk

 

[-PB-]

I also have the same problem with my encore. I end up getting impatient and closing the bypass damper too early and go to sleep before the cat lights off. I know this gunks up my cat but after a night of work and at 1am I just get too tired and lazy. I am going to try raking the coals back toward the throat hood.

Henk,
I have no idea what you wrote but it sounds good when I read it. Waaaay over my head dude!

Just kidding, I do understand some of it. Thanks for the input, you are helping others too.

 

[Mandoo]

This is what works for us.

Rake coals forward allowing ashes to drop into pan. Strategically add a couple small pieces on the coals then load it up (I mean stuff it full) sometimes I have to fight with the load to get the stove top to close all the way. Turn the air all the way on and of course leave the bypass open. When the pipe temp hits 400deg and stove top is at 500-600 we engage the Cat. At this point the cat does not register but starts climbing at a decent rate and once it does we turn down the air 1/2 or less depending on the wood and reload vs cold start This process takes 1/2 to 45 minutes cold start and 1/2 or less on reload.

We love this stove and the extreme burn times 14 hours + sometimes but never less than 12, It takes some time to get to know how it reacts and the timing needed to make it efficient. Yes sometimes I'm in a hurry and book out the door kicking the Cat in too early and yes it will burn cold and smoky creating creosote but once a year cleaning of a little of the fine powder stuff do to me in a hurry or the few crappy pieces of wood that may make it in the stove is no big deal. The hard shiny stuff is a major deal! I never see it.

I hope this coffee induced rant may help you or at least help you realize the potential........


One last Mr. Obvious thought. A solid mass with no air gaps will not burn as hot or fast as the same or smaller mass with gaps thats why it's lighting of faster with the hotter short term burns your throwing at it.