Cat stove vs Re-Burn tubes... which is more efficient?

[777funk]

I had a Cat stove in our last house and was glad to have it after years in that house with no wood heat. It would heat 1200 sqft with no problem even in the coldest of days. I was always curious about the new stoves with reburn tubes instead of cats. Is the cat going to be a more efficient fire? I do know that it was pretty light on wood use. Winters were 20F-40F most days and with only a few weeks of colder weather to the extreme of -5F or so.

 

[begreen]

Just discussed recently. This thread may help.
https://www.hearth.com/talk/threads/bk-vs-secondary-combustion-stoves.162935/

 

[lsucet]

Hi, for sure there is a lot of information on this site thàt can help you understand the difference between both technologies and how they work. Do some search and you will have days and days of reading.lol

 

[kennyp2339]

Both are great stove technologies. Certain cat stoves fair far better than others, just like certain reburn stoves. The key to everything is to find what you like.
I have a BK princess in my basement, it does a decent job heating the house (my floor plan kinda sucks upstairs) so I'm looking to install a small Englander (17vl) upstairs to help out when we get into the single digits during winter.
I love my BK for the burn times and how simple it works, I also like the Englanders due to there proven reliability and built heavy duty. The 17vl looks to be a great convective heater with a steel jacket around the unit, the 1.1 cu fire box should yield a 4-6 burn time. If I were to load 1.1 cu ft of wood in the princess I'd prob get a 10hr burn.

 

[777funk]

I understand how they work having owned a Cat stove and the secondary burn tube idea is very simple. It's not the understanding so much that I'm curious about. I'm more looking to find if one technology is better than the other in terms of efficiency and clean burning (i.e. less BTUs wasted and going up the chimney).

 

[bholler]

I understand how they work having owned a Cat stove and the secondary burn tube idea is very simple. It's not the understanding so much that I'm curious about. I'm more looking to find if one technology is better than the other in terms of efficiency and clean burning (i.e. less BTUs wasted and going up the chimney).

In that respect good cat stoves are better. But not massivley

 

[blades]

cats excell at longer slow burns and still keeping things clean. tube stoves are faster burning not as good on slow long burns- overall btu output about the same/per load just the time differential to get to the total. As far as how much btu wise goes up the tube hard to say I do not believe I have ever seen or heard of any testing or specs along that line. Not that recovery of said exhaust heat has not been something that has not been looked at over the years but there is a fine line of just how much can be pulled with out creating a creosote issue. We are all aware ( well I hope we all are ) of the magic heat box ( or as I call it the magic burn the house down box) and its related issues. There is a firm , I think in AU, that has a different approach but not anything new in the scheme of things. And then there were/are the creative multi flue designs to gain addition radiated heat from the exhaust gases. There were also stoves made with heat ex-changers as part of the stove in the exhaust train with various ways of self contained methods to clean them off, prior to the EPA mandates for the most part that knocked so many creative designs off the market (good, bad ,or in between). There was a design from a guy in MN ( around 2000-2003) that was a tube stove with stack of heat exchanging tubes in the exhaust stream prior to the flue exit ( top rear exit) internally there was a plate that could be pulled back and forth by a rod out the front to scrape the tubes off. the AU design looks to be a series of tube/s around a central flue pipe and the an external cover with fan induced flow through the tube/s at some $700.

 

[Highbeam]

Not sure why nobody will answer your question. Cat stoves from the two major manufacturers are decidedly more efficient at all outputs. Usually a 5-10% lead according to the published epa list. Now whether 5-10% is significant to you is a personal question but the wood savings will easily pay for new cats plus many cases of beer.

The cat stoves burn cleaner too since a cat can eat many more of the nasty compounds than just particulate.

The reason i want the cat stove in my home is that it has ability to provide heat at a very wide range of outputs to match the wide range of heat demands i have to maintain my house temperature. This results in very long burn times that no noncat can provide. Refill the stove once per day and keep your house warm.

I have a tube stove in my shop and used to use a tube stove in my house. They work too but after using both, the best choice is obvious.

 

[begreen]

I wouldn't get obsessed with a gram difference in emissions. Both technologies are good in different circumstances. A lot of the efficiency is in how the stove is burned. When a cat stove is pushed for winter heating the difference can become moot. An inexpensive Englander 30NC tests at 1.63gm emissions while a Blaze King Princess comes in at 2.42gm. That in no way makes one superior. As Highbeam noted, he wants low heating for his home for milder weather too. There the Princess excels. We are fortunate to have a good heat pump system and live in a bit milder temp zone, so for our home this is not an issue. It's much cheaper and cleaner for us to heat in 50º weather with electrons. Other homes have great solar gain and good insulation so their needs may also be different. Some folks need a stove that works with a shorter chimney, etc.. Different strokes for different folks. That's why we have a diverse number of options.

Far more important than the last nit for emissions or efficiency is the stove design, construction, and features that make it a good fit for your home and lifestyle.

 

[777funk]

Good answers. All I've ever known to date as far as wood heat was a cat stove. I enjoyed it and it seemed to be a good heater and wood miser at the same time. So it's nice to hear the other side of the coin. The stove I just picked up is a small Lopi with neither a cat nor burn tubes... just an angled fire brick baffle up above the flames. We'll see how it works. It's about half the interior volume of my old cat stove.

 

[begreen]

That old Answer is a room heater. It will not be as efficient as the modern Answer or a cat stove.

 

[jetsam]

It depends how you use the stove, too. If you use the stove for primary heat in shoulder season, the cat is going to be better/more efficient because it can start its reburn at 400-500°F and maintain it at low air settings. If you are burning every load on the 'fiery flames of hades' air setting, then you are not going to see much difference.

People comparing cat and noncat stoves that they've actually had is problematic, because the efficiency of both types varies widely. "I had both, and the one was terrible and the other was great." Yes, but maybe you had a terrible stove and a great stove... this doesn't necessarily say much about cats vs. tubes.

This is kind of typical of any wood stove debate though- the wide range of designs, installations, fuels, heating requirements, and operator procedures pretty much ensures that any discussion is going to go south at some point.

 

[blades]

Naw it doesn't go south but up in smoke

 

[BKVP]

I wouldn't get obsessed with a gram difference in emissions. Both technologies are good in different circumstances. A lot of the efficiency is in how the stove is burned. When a cat stove is pushed for winter heating the difference can become moot. An inexpensive Englander 30NC tests at 1.63gm emissions while a Blaze King Princess comes in at 2.42gm. That in no way makes one superior. As Highbeam noted, he wants low heating for his home for milder weather too. There the Princess excels. We are fortunate to have a good heat pump system and live in a bit milder temp zone, so for our home this is not an issue. It's much cheaper and cleaner for us to heat in 50º weather with electrons. Other homes have great solar gain and good insulation so their needs may also be different. Some folks need a stove that works with a shorter chimney, etc.. Different strokes for different folks. That's why we have a diverse number of options.

Far more important than the last nit for emissions or efficiency is the stove design, construction, and features that make it a good fit for your home and lifestyle.

Keep in mind the Sirocco 30.1 has a weighted average of .80 gr/hr and is almost the same firebox as the Princess in size.