question for BK Princess owners

[brian89gp]

The back story:
I have a house that has a heat loss around 200k BTU during the coldest days, too much for any single stove/insert to handle. I also prefer inserts and are restricted by rather small original fireplace openings. In effect, no single stove is enough and as a side effect once it gets to 50* or below outside I am in a full on 100% burn in the secondary burn Buck I have now. Expected cord usage per year is around 7 assuming I am able to run that much wood through the single stove this winter.

A full on 100% burn in a medium size secondary burn stove takes a lot of messing with and time. I get maybe 3-4 hours tops but usually in the 2 hour range between adding more wood or messing with the air dampers to burn down the coals faster or something. My goal is to try and keep the stove face temp at 600-650 with the blower on high.

But, I am looking around and find that the BK Princess insert will fit my fireplace opening and the efficiency rating differences between it and my Buck is about 1 cord less per year of wood.

I hear about the BK Princess being a lot easier to handle but I imagine that is in a house that the Princess is able to heat all by itself. How would it perform in my situation burning full out? What would my expected burn times and the amount of time I would need to be fiddling with it be?

I do plan on adding another insert in the other side of the house but due to a small firebox opening and a old ornate mantle, I am stuck to a insert with a small firebox size (less then 2 cu/ft). It would be good for quick burns to take the chill out on the coldest days, but the other primary insert (Buck now, maybe swapped for a Princess) is what is heating the majority of the house still and will be running 24/7 during the whole heating season.

Thoughts/opinions/tips?

 

[rdust]

I hear about the BK Princess being a lot easier to handle but I imagine that is in a house that the Princess is able to heat all by itself. How would it perform in my situation burning full out? What would my expected burn times and the amount of time I would need to be fiddling with it be?

Burn times burning "full" out will be no better than any other stove in the 3 cubic foot range in my opinion. The benefit of a cat stove is the ability to burn clean at a low burn, by the sounds of it this is something you you won't be able to use do to your heat loss. May be best to tighten the joint up some before playing the stove swap game.

 

[brian89gp]

So running a secondary burn stove and a cat stove at full burn they have similar efficency ratings?

 

[Highbeam]

So running a secondary burn stove and a cat stove at full burn they have similar efficency ratings?

There are some real non-cat dogs that will never be top performers but in general a non-cat at higher burn rates is quite efficient, that's where they shine.

If your target burn rate is that high then you need to be looking at different technologies like wood furnaces or boilers. Frequent fueling and short stove life expectancy and general unhappiness will result if you try and run a woodstove full blast all the time. If you are willing to give in and only partially heat with a stove then a huge cat stove like a king (not an insert) run at 50% will be a heat machine.

 

[brian89gp]

What about the efficiency of a secondary burn stove in the period between where the secondaries go out and it is time to reload? On mine that is usually around 2/3 of the burn cycle. If I sit there and play with the air I can get the secondary burn to go on longer so I know there is some extra heat to be gained. Does a cat stove have an edge in this operating range?

One thing that caught my eye about the Princess Insert is the thermostatic air control which I assume if I set it on "3" would open up further and further as the burn cycle nears the end to keep the heat output high.


Due to a variety of restrictions, design considerations, general layout, and existing construction I am pretty much stuck to two inserts, one 26" wide max and the other 24" wide max and both with a max liner size of 6". I have the space to put a free standing stove with a 6" liner in on the 3rd floor to heat that 1200 sq/ft, but that is a project for later. The other two chimneys are on the first floor on each end of a 30' x 45' house (with an addition on the back) and heat the roughly 3200sq/ft that make up the first and second floor. Boilers, furnaces, and very large inserts/stoves just aren't a possibility without spending a huge amount of money to make them work. Although a lot of manual labor to keep them going, inserts are very cheap in comparison.

 

[Snotrocket]

If you're losing that much heat your biggest priority should be sealing up the house.

Just for reference, if it warms up to 50 outside I have to let my stove go out or it will drive me out of the house. Even after it has gone out the amount of stored heat in my center chimney will keep the house above 70 for the next 24 hours after.

Put your money where it matters most. Sealing up the house.

 

[brian89gp]

House is sealed as well as its going to get, already put my money into all of that. It is very large, old, and has a ton of large windows. The heat loss of 200k for a -15* F design temp for 4400sq/ft not including the basement (which is also heated because it is used as a workshop) isn't outside the realm of reasonable. I can go into detail explaining my house and what I have done to improve efficency if it helps.

 

[Todd]

What about the efficiency of a secondary burn stove in the period between where the secondaries go out and it is time to reload? On mine that is usually around 2/3 of the burn cycle. If I sit there and play with the air I can get the secondary burn to go on longer so I know there is some extra heat to be gained. Does a cat stove have an edge in this operating range?

One thing that caught my eye about the Princess Insert is the thermostatic air control which I assume if I set it on "3" would open up further and further as the burn cycle nears the end to keep the heat output high.

The beauty of the BK t-stat is how it gives out a nice long even heat without the up and down heat spikes of a noncat. I haven't burned mine at #3 very much but I'm thinking it would give more heat overall in a longer burn at #2. With my Princess higher settings sends too much heat up the flue and seems like a waste of fuel. Sometimes I'll open her up towards the end of the burn cycle or to take the chill off then turn it back down.

I think you would do a little better with a BK but like others have stated insulation and fixing leaks may help even more and cost less than a brand new 3k insert.

 

[brian89gp]

I think you would do a little better with a BK but like others have stated insulation and fixing leaks may help even more and cost less than a brand new 3k insert.

I am buying another one anyway. The one I have now would be probably downgraded to the 3rd floor for bedroom heating duty. Only need it running for 8 hours overnight there, not all day as a primary heat source.

The beauty of the BK t-stat is how it gives out a nice long even heat without the up and down heat spikes of a noncat. I haven't burned mine at #3 very much but I'm thinking it would give more heat overall in a longer burn at #2. With my Princess higher settings sends too much heat up the flue and seems like a waste of fuel. Sometimes I'll open her up towards the end of the burn cycle or to take the chill off then turn it back down.

Does it feel like it is cranking out the heat any more at #3 vs #2?
Say you set it at #2 at the peak of the burn, will it open itself up to keep the fire hot once it goes more and more into the coal stage?

Thats my main beef with the Buck, I get a lukewarm stove (200-300) and a bunch of coals. To keep out of inferno from hell secondary burn I have to crank the air down, but once the fire goes to coals it isn't enough air to keep the coals and stove hot. If I gradually open the air up as the coals burn down I can keep the stove at 400+. Problem with that is I got to mess with it every 30 minutes or so.

 

[Highbeam]

Thermostats are great and basicly act as you describe. With a full load of fuel you set your stat at say #2 and the butterfly will open and close to try and maintain the corresponding stove temp. On colder days the stat stays open more and so your fuel load will be consumed faster. It's a beautiful thing and I don't understand why it is not more common.

 

[brian89gp]

Thermostats are great and basicly act as you describe. With a full load of fuel you set your stat at say #2 and the butterfly will open and close to try and maintain the corresponding stove temp. On colder days the stat stays open more and so your fuel load will be consumed faster. It's a beautiful thing and I don't understand why it is not more common.

Does it operate with air temp or stove surface temp?

 

[rdust]

Say you set it at #2 at the peak of the burn, will it open itself up to keep the fire hot once it goes more and more into the coal stage?

It doesn't open past "2" as the stove cools, it will open to the point of "2" and that's it. If you want more heat once it's cooling down you have to turn the knob to a higher number("3") The T-stat does a good job managing the burn while the fire is active to maintain a pretty steady stove temp.

 

[rdust]

Does it operate with air temp or stove surface temp?

It's not room air temp, the bi-metallic thermostat is on the back of the stove so it's more about stove temperature. If the stove is too close to a wall BK has said it may cause the t-stat to function improperly so radiating heat must have some affect on it. This is the reason the insert has the t-stat mounted in a different place when comparing to the freestanding stoves.

 

[Highbeam]

Does it operate with air temp or stove surface temp?

The thermostat coil is enclosed within the stove's skin. It is not exposed to room air temp or intake air temp. To answer your question, stove temp.

One theory on what happens is that a cool room takes more heat from the stove so the stove cools and the stat opens. The other theory is that cold outside temps cause a stronger draft which makes a given stat setting allow more air to be sucked into the fire which will speed up burn rate on colder days. Either way, the stove automatically burns more wood when it needs to to maintain room temp.

Magic? perhaps.