When looking at stoves and BTU per hour a piece of wood has a set amount of BTU. The efficiency % between 76% and 80% is not huge and this is running on high heat output. Is the main benifit of a catalytic stove to be able to run lower heat for longer burn times when you are in the off seasons or if your stove is over sized?
Efficiency of secondary, catalytic and hybrids?
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Yes, that is the main benefit. When pressed for heat the difference is insignificant. The variation from wood load to wood load could be greater than that.
That depends entirely on the stove. There are notable differences between stove models and secondary or cat combustion design. Some non-cats like the Lopi Evergreen are almost equivalent. Others are around 74% vs say 78% for the cat. OTOH, there are non-cat designs that have lower efficiency too.
I wish the stoves had more common metrics, I feel as you run them lower and lower the catalyst is more and more efficient compared to a secondary. Both will only go down so far though till either the catalyst can not sustain itself or the secondary burn stops. When running on med/high I feel the differences may end up being negligible and as said above the wood you add to the stove would make more of a difference.
I have a Napoleon 1900 and I only run it on low once the secondaries are established but it takes off like a freight train and I couldn't slow it down if I wanted it too which makes me feel It only ever runs at high once it gets going.
One thing I find interesting is the listing for btu/hr listing for blazeking princess is 12k/33k. When looking at the Quadrafire 5700, Regency 3500 and Napolean 1900 the Max btu listed is 72-85k which seems crazy.
I have a Napoleon 1900 and I only run it on low once the secondaries are established but it takes off like a freight train and I couldn't slow it down if I wanted it too which makes me feel It only ever runs at high once it gets going.
One thing I find interesting is the listing for btu/hr listing for blazeking princess is 12k/33k. When looking at the Quadrafire 5700, Regency 3500 and Napolean 1900 the Max btu listed is 72-85k which seems crazy.
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Would a stove like a PE Alderlea only get minimal benefit by adding a catalyst? Would adding a catalyst to a stove with a good secondary burn only gain a few % in efficiency?
Simply adding a cat to a stove isn't going to change anything. The stove would need to be completely re engineered
Todd
Minister of Fire
Maybe your draft is too strong and a pipe damper could help. Cutting off the unregulated primary boost air may also help. Could also be that your turning your air down too late. Do you have a pipe thermometer?
Those BTU numbers could be the difference between crib wood testing and cordwood testing. There are many non cats that have a good BTU range and decent control at low but you need a proper setup.
I have been playing with it a bit using a magnet on the primary and secondary. Primary is harder to cover as they use the same rod and the plate slides back next to the primary. I had one magnet covering a bit of it but it got moved then flipped over to the inside. To hot to fish it out now. Is it better to limit primary or secondary air?
Edit: I put my big magnet over half of the secondary when fully closed. Will see how tonight goes. The round magnet was only thing that would fit in there but I didn't account for the control coming all the way back on fully open. I could have compared full open and closed first. I could use foil tape but would require me to take it a part to get it on ( Looks like 4 machine screws ) . Chimney goes from basement ceiling to outside then straight up above the roof. I should measure it out sometime.
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Todd
Minister of Fire
I’m not familiar with your stove but Try looking in your fire box bottom middle front below the door for a hole where some of the primary air comes in. Some people call it the dog house. This setup is in a lot of non cat stoves and it gives a boost in primary air right into the bottom middle of the load. This is sometimes so strong (especially with tall chimney) it acts like a blow torch ripping through the middle of the wood in the fire box. Mine has two holes that I blocked by inserting a couple screws. This helped slow down the strong primary burn and gave me more control.
DBoon
Minister of Fire
I ran a Lopi Answer small tube wood stove for many years - great stove, well-built, drafted well with a short chimney installation, put a lot of heat into the room with the blower and the jacketed design.
Now I have a Woodstock Keystone catalytic. It has a similar sized firebox to the Answer (maybe a bit smaller). I can tell you that I think the catalytic results in a 25% or so reduction in the amount of wood used for a given amount of heat. My belief is that the catalytic stove efficiency ratings are more "real-world" - you will get that efficiency with the catalytic converter working - and the tube stove efficiency ratings are for a burn that is probably in some sweet spot that is hard to achieve in a normal setup (i.e., not the tested flue height, draft, wood species, moisture content, etc.).
So while the numbers look comparable for tube stove versus a catalytic stove, you are much more likely to get much better efficiency with the catalytic stove since it is so much easier to run it in the controlled (as measured) burn conditions.
Now I have a Woodstock Keystone catalytic. It has a similar sized firebox to the Answer (maybe a bit smaller). I can tell you that I think the catalytic results in a 25% or so reduction in the amount of wood used for a given amount of heat. My belief is that the catalytic stove efficiency ratings are more "real-world" - you will get that efficiency with the catalytic converter working - and the tube stove efficiency ratings are for a burn that is probably in some sweet spot that is hard to achieve in a normal setup (i.e., not the tested flue height, draft, wood species, moisture content, etc.).
So while the numbers look comparable for tube stove versus a catalytic stove, you are much more likely to get much better efficiency with the catalytic stove since it is so much easier to run it in the controlled (as measured) burn conditions.
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