Coal bed, schmoal bed.... I do not do worry about that.... when the exhaust gas and STT is hot enough (400 -450 for me) I throw the cat in. Without the coal bed it may stall out, but then you just open the bypass, heat it up and try again. Without a cat you may need more heat to get the secondary burn to sustain.
@arnermd unfortunately I think you might be VC R&D as far as temperature exposure and refractory life. I understand that the data logger is new this year - Hopefully you’re defining the 20 year refractory life setup now. Any idea what you were running the 3 years between failures?
Yeah I did not consider that.... couple be a thermocouple issue. Easy to check, pull it out and stick it in the stove pipe.
Last night I... I mean a friend of mine.... fell asleep on the couch, woke up and reloaded the stove with the bypass closed and a really hot bed of coals. Cat went from 600 to 1200 in less than 2 minutes..... When I finally came to my senses I thought... something is not right..... duhhh.... Can't believe I (I mean my friend) did that......
My fan is temp controlled. But I pretty much always leave it running to move the heat. Rarely does my stove get cold enough it turns off. The only time I turn it off is if I want to watch a movie I can't hear. Otherwise it stays on full speed all the time. I have the stove in a hearth and a less than ideal layout so I need to move air. Tried running it no blower and the far parts of the house stay too cold
It was not me, but there was one member back then that was charting the cat activity. Can’t remember his name.
I bought the data logger last year, mid season. But your point is valid, I do not have recorded data from the refractory failure days.
I do not use, and never have used, convection fans. I have a peltier fan that sits on the stove top but that's it. One time I experimented with secondary air. I forced air, with a blower, into the secondary inlet. It definitely worked, I could control secondary temps by forcing more air to run on the lean side of stoich. I did not run it unattended or for long, forcing air into a firebox with no safety's is a bit to risky for me.....
Yep for sure.... this is a really great forum. I really wish we had a stove designer participating in the discussions. Sometimes I feel like we are just a bunch of monkeys trying to figure out how to drive a car.....
It's a liner going in a masonry chimney. Two story colonial, maybe 25'. They told me they would access with an extension ladder but it was drizzling the day of install so they brought a lift. They couldn't set up where they wanted to because the ground was so wet after a few days rain, tried it from a patio but couldn't reach. Overall it was a comedy show - took them two hours to set up and realize it wouldn't reach. They are coming back today.
I'm curious.. what is your source of catalysts?I bought the data logger last year, mid season. But your point is valid, I do not have recorded data from the refractory failure days.
As with all things my memory is a little fuzzy and there are no definitive conclusions I can draw. Pretty sure all my refractory failures are documented in prior year threads, but here is what I recall....
- When new I only had STT magnet. So I had no idea what the cat was doing, ignorance was bliss.... My guess is the cat was running consistently in the 1600+ range.
- The original refractory lasted 3 years I think. It did not crack, the rear piece (VC calls it a Refractory, Engine) actually warped causing smoke to bypass the cat. I plugged it with some insulation and ran the rest of the season. The surface showed heavy spalling, indicating it was running hot.
- The second refractory actually cracked, again it was the refractory engine. At this time I had cat temp monitoring but no data logging. As best I recall my over-temp alarm was set to 1650+ so I could sleep once in while. I did run for a while with no cat. It too showed spalling but not as heavy as the first one.
- I am not entirely convinced the failures were a result of over firing. There is part of me that thinks they were manufacturing defects that were exacerbated by the high temps. Very hard to know for sure.
- I just looked through my records and I replaced cats in 2015, 2017, 2020, 2022. I installed the stove in Feb 2012. So the life of the cats were: 3, 2, 3, 2 years. That's 2.5 years on average. I know some of them I stretched by piecing some broken ones together.
- Failure mode is always ceramic crumbling, the ceramic grid cracks and chunk simply fall out of the frame. I suspect this is a result of flame impingement.
- The steel frames always warp on the lower back side of the cat. I started making either bands that slip over the cat frame or wrapping the frame in stainless wire to help the frame keep its shape. Definitely helps..... but then the ceramic just falls apart.
- This years cat is not looking so good after only 3 months of service..... it has several cracks and one small section has already broken. Next cat will be steel for sure.....
- I only mention cat life as I think it is an indirect indicator of secondary temps. The cat life has been pretty consistent so that tells me the stress level on the refractory has been consistent through the life of the stove.....
- I also would be remiss if I did not mention that VC replaced the refractory, both times, under warranty. The biggest inconvenience is that it takes months to get the new parts, and then I had to rebuild the stove, twice.
- My stove has a lifetime warranty on refractory, but not the cat. I do not believe this was offered for too many stove models.
I do not use, and never have used, convection fans. I have a peltier fan that sits on the stove top but that's it. One time I experimented with secondary air. I forced air, with a blower, into the secondary inlet. It definitely worked, I could control secondary temps by forcing more air to run on the lean side of stoich. I did not run it unattended or for long, forcing air into a firebox with no safety's is a bit to risky for me.....
I have considered using my Watlow controllers to run closed loop control and vary blower speed to regulate secondary temps. Just have not had the time or motivation to try that. Seems excessive for something that should just work.... and the failure modes for forced air combustion are very ugly.
Yep for sure.... this is a really great forum. I really wish we had a stove designer participating in the discussions. Sometimes I feel like we are just a bunch of monkeys trying to figure out how to drive a car.....
Eventually some of us will (and have) figured it out....
Wouldn't it be great if VC actually had someone that answered the phone and a tech department! Pretty frustrating when you call they automatically refer you to a dealer for tech assistance. I can't see being a VC dealer unless the profit margin is big enough to have to be their tech line too.Yep for sure.... this is a really great forum. I really wish we had a stove designer participating in the discussions. Sometimes I feel like we are just a bunch of monkeys trying to figure out how to drive a car.....
Eventually some of us will (and have) figured it out....
The first two catalysts were ceramic from Hearth and Home, they were as purchased and warranty replacement from VC. The next three were from Condar (CC-800). None of them were a tight fit, snug I would say but easily slid into place if it was squared up.
FWIW, I've cobbled these catalysts sources together from this forum:
