Kuznetsov Boilers -- Field reports from Russia and Canada

[cguida]

There's not a lot of information about Kuznetsov boilers, but here are some reports gathered from around the web.

The Monastery in Ekaterinburg --

Alex Chernov reports on his website
http://www.stovemaster.com/html_en/wood-burning_boilers.html

This boiler successfully heats a three-story 11000 sq ft brick temple in a monastery near Ekaterinburg, Russia. The boiler's outside dimensions are 6x6x7ft high. The boiler's output is 200000-425000Btu depending on the firing pattern. The temple's hydronic system (cast iron wall radiators) is fed by gravity. Boiler is insulated from outside and is currently fired 3 times a day. The monastery is located in the cold climate zone with winter temperatures dropping to below - 30° Celsius (similar to Central Quebec, Canada). If you want to find out more about design of the boilers please read an article by Igor Kuznetsov here. www.stove.ru

 

[cguida]

The Perm boiler (no picture -- resumably similar in design to the Monastery boiler)

(Perm is in central Russia, way east of Moscow)

Quote: http://www.stove.ru/index.php?lng=1&rs=171

Boilers built in conformance with this technology show fantastically amazing results. This fact is confirmed by the results of operation of wood-burning boiler of our System in heating season of 2005-2006 built by VIST JSC in Perm, tel.+7 (342)2530164, [email protected]. The boiler has overall dimensions 195x 169 and is 210 cm in height. It heats the shop having the size 36 x 16 m and 9m in height, including 60 m2 of two-storied section. The walls are made of brick, 52 cm thick.
The square of the shop is: 36 x 16 + 60= 636 m2. The volume of the building is: 36 x 16 x 9= 5184 m3. The demand in piping is 57 x 5, (10 x 149+2 x 123) x 4 = 70 running meters for the boiler. The pipe heat surface is 3,14x 0,057x 70= 12, 52 m2 which approximately corresponds to 126 kW. The output temperature was 65-70° C (could be higher), it was not measured at the output. Pine rough edge, not dried was used as fuel, 1 m3 per day. The power achieved by combustion of wet pinewood was 57 kW. The representative of the company Mr. S.A. Mashyanov admitted that the boiler maintained temperature of 18°C in the workshop while the outside temperature was almost – 40 ° C. This fact should be confirmed or denied by performing tests. Other customers admit good operational features of the boilers as well.

[here is basically the same information, translated for us english-measurement people...]

http://heatkit.com/research/2008/Hydronic/Igor's comments about boiler.htm

Boilers built according to this technology show exceptional, unbelievable results. You can load green wood and brown coal with 45-55% of moisture content. Steam that is produced during combustion of such fuel in our boilers doesn’t interfere with combustion and heat exchange and passes in the lower portion of the bell into the chimney.

Such facts are proven during operation of a boiler built in Perm, Russia, company “VIST” 8(342)2530164, [email protected] This boiler has dimensions of 195smx169smx210sm. It heats 115 x53ft x 30ft high building that has 20”-thick brick walls with no insulation. Surface area of the heat exchangers is 12.52 sq m, that approximately can produce 126kWt. Temperature at the outlet fromt eh heat exchangers is 65-70C (can get higher if needed). Fuel used: wet pine cut-offs from squaring the logs. Consumption: 1 ì3 a day. Such fuel in its condition can only give out 57kWt."

[again the joys (and frustrations) of junk softwood... A cubic meter a day is alot of wood, even by my somewhat wasteful standards. I make it out to be about .2 cord a day -- maybe a cord and a half per week. Still, being able to heat a big place like that in mid-winter on WET junk softwood is pretty remarkable. We eagerly look forward to more data.]

 

[cguida]

The Perth Onterio Chernov Workshop Boiler

It is possible that this is the first Kuznetsov boiler in N. America.

This link is a very well-done, start-to-finish, illustrated presentation of how the boiler was put together. It's not often you get to see the insides of one of these things.

http://heatkit.com/html/lopezs.htm

Attn: Potential Seton Builders -- note the relatively simple heat exchanger -- no bending.

There are links to comments at the end, both from Chernov, and Kuznetsov himself. Also, there are also comments from the owner of the boiler, who reports that it keeps his shop at 50 degrees with one firing a day with outside temperatures at 0F.

If anything, the boiler works too well. Or rather, they need some storage. The radiant slab in the shop is not capable of absorbing boiler output from a second firing/day without blowing safety valves. A storage tank would fix this easy.

We don't yet know much about the dimensions of the firebox, wood consumption, wood type, etc. The investigation is continuing...

 

[Nofossil]

Enthusiasm and hard data are often uncomfortable bedfellows....

A cubic meter a day is just over 1/4 cord per day. or just under two cords per week. Whether that's good or bad depends entirely on the heat loss of the building. My guess is that the Slantfin spreadsheet will not work so well for such a structure ;-)

Having spent a good deal of time on analyzing wood combustion, my best understanding is that it's not theoretically possible for a non-condensing wood boiler to exceed about 93% efficiency with wood at 15% moisture content. Some energy MUST be lost up the flue in the form of water vapor and flue gas that's heated enough to prevent condensation. As the moisture content goes up, the maximum possible efficiency goes down. I don't remember the derating factor, but a ton of wood at 50% MC requires enough BTUS to boil 1000 lbs of water. All of that energy is lost up the chimney.

Condensing boilers can do better, but masonry chimneys are not suitable because the acids in the condensate weaken and dissolve the masonry over time.

There may be many possible wood burning appliance designs that perform well, but unless the laws of physics are revised, nothing will do much better than a well designed gasifier that's operated well - they can achieve a boiler efficiency of 90% or better out of a theoretical maximum of 93%. System efficiency will be less than that, but all boilers will suffer a similar loss between boiler efficiency and system efficiency.

 

[kuribo]

many advantages to a masonry boiler.....less fuel sensitivity, fewer moving parts, potential to cost less via self build, options for ovens and fireplaces, simpler construction, longevity, etc.....

 

[Ugly]

I still think the ultimate reason for following along with a Kuznetsov design in the first place is the sheer asthetic pleasure. I'm pondering a new stone house and I admit, I'm heavily tempted by something like this. A small castle in the bush with a Russian boiler for heat and fuel.

Someone in the forums here said (paraphrase) "I don't care what my boiler looks like". I do, I've spent a bloody fortune in money and labour changing this property from a bramble of brush into a nice looking estate. The last thing I want (for example, not naming any names) is something with a camo painted door sticking up in the middle of what is really a cultivated forest.

Interesting stuff Smee, I'm going to make it a point to see some of this in person, it's just that neat.

 

[Floydian]

I agree to some of the advantages of a masonry boiler-especially the DIY part. But for it to function well it's just as reliant on circulator pumps as any other boiler. Plus firing for DHW in warmer weather is not appealing to me but paired with solar hot water, it would be a nice balance.
It might be an advantage to be able to burn higher moisture wood for some, but I agree with nofossil-performance will suffer some.
I have a friend who built a masonry stove and he sees a big difference with very dry wood.

Noah

 

[kuribo]

Like everything, there is no one perfect solution. Masonry boilers do present a number of advantages as listed above, that make them very attractive in some, but not all, circumstances. Clearly the aesthetics are a major plus for many with the right situation. They do need circulator pumps but do not need draft fans, controllers, automated dampers, etc. And the option to include a bake oven to bake pizza is not to be overlooked!

 

[cguida]

In the right circumstances, masonry boilers don't even need the circulator. Chernov says Ekaterinburg monastary boiler is gravity feed.