VC Intrepid II catalytic operation

[woodslayer]

Hello everyone. I installed a VC Intrepid II to heat our family room last year. I'm struggling with the catalytic operation of this stove. I may have a draft problem or a MC problem or a combination of the two.

My Rutland griddle surface thermometer has a "burn zone" of 300-600 degrees. After starting the stove I wait until the temperature gets to 600 degrees and a good bed of coals before closing the damper. When closing the damper I will often hear a blowtorch sound if I wait until griddle temp reaches 600 that I don't get at lower temps. Is that the sound of the catalyst lighting off? Can the damper be closed at lower temperatures?

Sometimes the temperature will maintain 550-600 after closing the damper, but not always. More often than not the griddle temp will fall off to around 400-450 degrees when I need the temperature closer to 600 to heat the room. So I have to open the damper to get the temperature back up, forfeiting the efficiency of the catalytic operation. I've noticed that there is often more smoke coming out of the chimney with the damper closed than with it open, and this is opposite what the VC owner's manual says I should be seeing if the catalytic operation is working. So I'm really not sure that the catalyst is lighting off or staying lit.

The stove pipe runs up a masonry exterior chimney. It does not have the best draft and I sometimes have to reverse the draft to get the stove started on a cold day. The wood is ash that has been outside covered for about a year. It burns well but is probably not fully seasoned. Over firing is definitely not a problem with this stove. I suspect that the draft may be inadequate and perhaps the reason why it's so difficult to get good catalytic operation out of this stove.

This is my first time posting. Splitting wood is my zen. I am addicted to wood heating and desperately want this to work. Any advice greatly appreciated!!

 

[ccg36]

Not sure if the Intrepid has same controls as the Defiant, but i get my stove to 500-600, engage the cat, then start to close the air control to dial in the temp i want the stove to run at. once dialed in, the stove is very temperature stable, even on reloads.

 

[muskokaPJ]

Hello everyone. I installed a VC Intrepid II to heat our family room last year. I'm struggling with the catalytic operation of this stove. I may have a draft problem or a MC problem or a combination of the two.

My Rutland griddle surface thermometer has a "burn zone" of 300-600 degrees. After starting the stove I wait until the temperature gets to 600 degrees and a good bed of coals before closing the damper. When closing the damper I will often hear a blowtorch sound if I wait until griddle temp reaches 600 that I don't get at lower temps. Is that the sound of the catalyst lighting off? Can the damper be closed at lower temperatures?

Sometimes the temperature will maintain 550-600 after closing the damper, but not always. More often than not the griddle temp will fall off to around 400-450 degrees when I need the temperature closer to 600 to heat the room. So I have to open the damper to get the temperature back up, forfeiting the efficiency of the catalytic operation. I've noticed that there is often more smoke coming out of the chimney with the damper closed than with it open, and this is opposite what the VC owner's manual says I should be seeing if the catalytic operation is working. So I'm really not sure that the catalyst is lighting off or staying lit.

The stove pipe runs up a masonry exterior chimney. It does not have the best draft and I sometimes have to reverse the draft to get the stove started on a cold day. The wood is ash that has been outside covered for about a year. It burns well but is probably not fully seasoned. Over firing is definitely not a problem with this stove. I suspect that the draft may be inadequate and perhaps the reason why it's so difficult to get good catalytic operation out of this stove.

This is my first time posting. Splitting wood is my zen. I am addicted to wood heating and desperately want this to work. Any advice greatly appreciated!!

 

[muskokaPJ]

I've had a VC Intrepid II since 1998 and used to get the blow torch sound you mentioned, but only in the first couple years...maybe my stove is not quite as air tight as it used to be. I always thought it was the stove "sucking air". It runs very well but I've learned quite a few things a long the way (this forum has a wealth of information on catalyst stoves...they all have similar "issues").

1). Invest in a catalyst temperature probe. Much more accurate in determining light off and watching the ups and downs of temperature for each wood load (everyone will fire different...even from the same seasoned wood)
2). Stove Top Temperature is a good guideline but is tricky. I can get varying readings depending on where its located (differences of 50-100 degrees). And stove top temps does not always represent heat output. It sounds odd but I too used to run it hot, as I thought it was the only way to get enough heat. Now that I am loading correctly and lighting off the catalyst properly, I can get blasting heat and sometimes the stove top thermometer only reads 450 F or less.
Get a deep bed of hot coals...minimum 3-4" and load progressively larger splits on top of that... almost to the top. I close the bypass damper at a catalyst temp of 600 though it can be lower. Stove top temp is normally near 300 F or less at this point. If the wood is seasoned and the coal bed is hot, catalyst temp will eventually rise to near 1500 F in 15 minutes. I start reducing air in 1/3's near the 1200 F. Maximum heat "output" normally does not get realized until the larger splits have lit. And from then on, it is heat city...and the stove top thermometer will still sit near 350-450 F.
3). I have burned maple and oak and seasoned or not, they do burn differently. I used to season wood, split and stacked for one year but the denser hard woods need more time. This VC air tight operates much better with drier wood (not cork mind you).

I now use a wood moisture probe to measure the wood pile, a catalyst temp probe and even play with a IR digital surface temp reader. And with all the gadgets (they have all helped at some point) using them and observing the patterns over a half dozen fuel loads, you'll see how to tweak your process to maximize the stove. I ran mine for 10 plus years until realizing I was not doing a few things quite right. But being woodpile/wood stove/gadget obsessed has netted me great happiness.

FYI search this forum site on how to rejuvenate a suspected masked or non-working catalyst. I followed the hot water vinegar method and it totally works.

 

[woodslayer]

Thanks for the great advice! I really appreciate you taking the time to reply to my post. This forum is a fantastic resource for us wood burning newbies.

I like your suggestion to install a catalyst temperature probe to take the guesswork out of when to close the damper and to get a better read on stove heat output. The Intrepid II owner's manual makes no mention of this option. It only recommends a surface temperature thermometer and closing the damper when the surface temp reaches 450. The stove is equipped with a factory installed catalytic probe thermostat that controls a secondary air inlet in the back of the stove. I'm not sure where I would install the temperature probe and how I would read it since it's in the back of the stove. I found some good info at Condar www.condar.com on operation and maintenance of catalytic combustors and catalytic temperature probes. I'll call Condar to see what they recommend.

The Intrepid II model 1990 was purchased new a little over a year ago. A picture of the catalyst is attached. It seems to be in pretty good condition and does not appear to be creosote fouled but could benefit from the cleaning that you mentioned. When the stove is fully up to temperature and a good bed of coals is established it seems to run pretty well with the damper closed and a surface temperature of around 350-400 degrees with the primary air inlet throttled back. It may be that the combustor is working and I just don't know it. What concerns me is that the stove consistently produces a lot of smoke when I close the damper and according to the Condar literature this is an indication of a failing combustor. So I think I'll give the cleaning a try before spending money on a new combustor.

Intrepid II model 1990 owners manual:
http://literature.mhsc.com/vermont_castings/manuals/2000966_Intrepid_II_34.pdf

Condar catalytic combustor maintenance guide:
http://www.condar.com/combustorcleaningmanual.pdf

We are enjoying our new stove. It really takes the chill out of our northeast winters. But it is a bit of a hassle to operate.

Brad

 

[muskokaPJ]

Thanks for the great advice! I really appreciate you taking the time to reply to my post. This forum is a fantastic resource for us wood burning newbies.

I like your suggestion to install a catalyst temperature probe to take the guesswork out of when to close the damper and to get a better read on stove heat output. The Intrepid II owner's manual makes no mention of this option. It only recommends a surface temperature thermometer and closing the damper when the surface temp reaches 450. The stove is equipped with a factory installed catalytic probe thermostat that controls a secondary air inlet in the back of the stove. I'm not sure where I would install the temperature probe and how I would read it since it's in the back of the stove. I found some good info at Condar www.condar.com on operation and maintenance of catalytic combustors and catalytic temperature probes. I'll call Condar to see what they recommend.

The Intrepid II model 1990 was purchased new a little over a year ago. A picture of the catalyst is attached. It seems to be in pretty good condition and does not appear to be creosote fouled but could benefit from the cleaning that you mentioned. When the stove is fully up to temperature and a good bed of coals is established it seems to run pretty well with the damper closed and a surface temperature of around 350-400 degrees with the primary air inlet throttled back. It may be that the combustor is working and I just don't know it. What concerns me is that the stove consistently produces a lot of smoke when I close the damper and according to the Condar literature this is an indication of a failing combustor. So I think I'll give the cleaning a try before spending money on a new combustor.

Intrepid II model 1990 owners manual:
http://literature.mhsc.com/vermont_castings/manuals/2000966_Intrepid_II_34.pdf

Condar catalytic combustor maintenance guide:
http://www.condar.com/combustorcleaningmanual.pdf

We are enjoying our new stove. It really takes the chill out of our northeast winters. But it is a bit of a hassle to operate.

Brad

View attachment 149457

 

[muskokaPJ]

Difficult to say by appearance, if the cat is "masked"...not able to function, but visually, looks no different than the ones I have. I purchased a replacement after about seven years of casual use but oddly never threw out my old one. The cat I'm currently using is my old original, refurbished and it's working perfectly fine (and I only replaced it because I suspected it wasn't working as it should...was never sure). The catalyst probe I am using is the digital Condar one and it had good reviews here...and is working splendidly. I opted for the digital one as I do have the heat shield and a standard one would not be readable...and who doesn't like digital! The manual makes no mention but they sure do provide a spot for it. If you have a rear heat shield, remove it and you will see on the removable back plate, a chrome looking plug. This pops out (you may need to remove this heavy removable plate to pop it and if so... you'll see the secondary air inlet/thermostat connected to a sliding air door). There is a hole already in the CAST and to insert the probe through you need to drill a small pilot hole through the refractory material. I've heard some people say they just push the probe through and the material is certainly soft enough, I just wanted a tight seal.I did this with the catalyst removed so I could see how far I was leaving the probe in. This already provided opening has the probe sitting just below the catalyst, right in smokes way! I read about this on an old thread which I cannot locate but was written up by a fella who, back in the day, either worked for the manufacture(s) of the first catalysts or maybe Vermont Castings. He wrote a TON on how cats work..a lot of technical stuff but the basics were very informative. I've included a partial copy of his article (apologies to the original poster for not knowing his forum name and not giving direct credit). He's a Chemical Engineer and new his stuff. I had heard from others that if the honey comb parts of the catalyst are intact and it's not all warped from over firing, the catalysts are still good (I don't believe the noble metals can actually burn out of the thing...just get masked). I also noticed in the attached document, the original poster warned of firing over 1200F. Condar info warns of extended burns of 1500 and I've certainly had mine spring up to 1800. But as I see it still climbing past 1300 (and it does not with every load), I gradually dial back air...1/3 at a time and slowly. The temperature on my catalyst probe never stays high for long...thankfully. And judging by some of the hot fires I've had before using a catalyst probe, I'm sure I've had "higher than recommended" catalyst temps and neither of my cats are warped from heat. Albeit my refractory material inside has a few missing pieces (perhaps due to excessive heat, but it's not too bad. Someone posted a pic here of a used Intrepid II they purchased and the refractory material was all but gone!!

I have always gotten some smoke puffing (from the chimney) when closing my by-pass damper but doesn't last longer than maybe 5 mins max. This changes with the wood load and DRYING wood is definitely key with catalytic stoves. They really like cut/split wood thats been aired for two seasons min... though it will burn it okay with one season. If you look at the emissions coming out of your chimney, by-pass damper closed, after ten minutes or so, should be almost nothing...light infrequent grey is sometimes normal...again depending on wood.

The great thing about these catalyst probe thermometers is they show catalyst operation by the rise in temp. If I close the by-pass damp at a catalyst thermometer temperature of say 500 or 600 degrees, the reading will steadily climb almost 100 degrees every few mins or so. This is another way to verify the cat is working. If it's soiled or poisoned, it will not climb in temperature (makes sense as when it "lights off" it heats up as it's burning smoke). But note, if the wood load is not well lit or too wet...cat temps will not rise and likely fall..indicating not necessarily a failed catalyst but just a fire not hot enough to start the catalyst function. I still watch the fire and the cat thermometer reading together and after a while you use both as indicators. I've had a few fires where perhaps the logs at the rear partly blocked the smokes route for escaping through the catalyst and so the probe thermometer registered less than 350 F (digital thermometer shows this as "cool"...not number reading) but my logs were well ablaze and the stove top thermometer was 400 F with lots of heat from the top. I closed the by-pass damp and the cat therm went up quickly to 800 plus. Hence you learn to use a bit of everything.

I love detail as is obvious from the length of this post. Hope it's of some help.

James

 

[muskokaPJ]

One more thing Brad. The page I attached was not from this forum but another I stumbled across. I've included a link to his entire article...interesting read!!

Look at the postings from "Steve in Mass"

http://www.stripersonline.com/t/480549/heating-with-woodstove-how-to-not-get-screwed/45

 

[woodslayer]

Wow.. Steve in Mass really knows his stuff!

I'm beginning to think that 90% of my problems can be attributed to the wood. Last year's wood was not fully seasoned, this year's wood is better and next year will be better still. It makes a huge difference in getting the stove started and maintaining temperature. Certainly dumping a full load of frozen wood into the stove will significantly lower the stove temperature (go figure! . With the stove fully up to temperature and a good bed of coals established the stove seems to be performing well with the damper closed and virtually no smoke coming out of the chimney.

The catalytic temperature probe is the only sure way to take the mystery out of when to close the damper. I found the chrome plug in the back of the stove that you mention that covers the hole for the temperature probe. Funny that the VC Intrepid II owner's manual makes no mention of this. Because of its location in the back of the stove I would need the Condar remote digital temperature probe and I'm not quite ready to plunk down the $120 for this gadget. For now I think I can get the desired performance using the stove top surface thermometer and the methods I've learned in this forum.

Thanks James for your very helpful and informative replies. I've learned a lot and I really appreciate the help.

Brad

 

[muskokaPJ]

Wow.. Steve in Mass really knows his stuff!

I'm beginning to think that 90% of my problems can be attributed to the wood. Last year's wood was not fully seasoned, this year's wood is better and next year will be better still. It makes a huge difference in getting the stove started and maintaining temperature. Certainly dumping a full load of frozen wood into the stove will significantly lower the stove temperature (go figure! . With the stove fully up to temperature and a good bed of coals established the stove seems to be performing well with the damper closed and virtually no smoke coming out of the chimney.

The catalytic temperature probe is the only sure way to take the mystery out of when to close the damper. I found the chrome plug in the back of the stove that you mention that covers the hole for the temperature probe. Funny that the VC Intrepid II owner's manual makes no mention of this. Because of its location in the back of the stove I would need the Condar remote digital temperature probe and I'm not quite ready to plunk down the $120 for this gadget. For now I think I can get the desired performance using the stove top surface thermometer and the methods I've learned in this forum.

Thanks James for your very helpful and informative replies. I've learned a lot and I really appreciate the help.

Brad

Glad to hear things have settled in. I also find adding cold wood does not work well. I have a book that suggests keeping two days supply inside...I do not have this kind of room but I'm sure it's a great idea. And I have definitely found the more seasoned/dry the better. And as an Old wood lot guy once told me, as long as you prevent the wood from getting wet/dry...wet/dry...stacked covered wood will stay good for quite some time.

Best of luck and glad I could help a fellow Intrepid II owner!

James