how are the long burn times achieved in the T5

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Apr 6, 2011
36
Sodus NY
Now that the cat in my DW stove is broken into pieces, I can’t keep a fire for more than a couple of hours. It’s been staying cold here especially at night, so I load it up as normal and in the morning there aren’t even any coals left to start another fire. I’ve always believed the honeycomb in the cat acted like a torturous path (or flue damper) that kept the supply air in check, providing a nice long fire when turned all the way down. I realize that my old stove probably isn’t as air tight as it was when I bought it. But my cat just recently showed signs of being broken so at the beginning and middle of the season I wasn’t experiencing this problem. Now that I’ve bought the PE T5 I’m wondering how the long burns discussed here are achieved. It seems to me that there is a direct path to the stove pipe. What is happening inside the PE to: #1. Prevent the chimney draft from sucking in clean air and burning up the wood? and #2. How does the stove achieve such long burn times?
 
Actually there isn't a direct path to your stove pipie, the baffle creates an S flow pattern that slows down the draft and the secondary air catches the smoke while it's still in the box creating a more efficient burn. To get long burns you will have to experiment with different loading techniques, usually raking the coals forward and loading larger splits will give you a longer burn.
 
gogreenburnwood said:
Now that the cat in my DW stove is broken into pieces, I can’t keep a fire for more than a couple of hours. It’s been staying cold here especially at night, so I load it up as normal and in the morning there aren’t even any coals left to start another fire. I’ve always believed the honeycomb in the cat acted like a torturous path (or flue damper) that kept the supply air in check, providing a nice long fire when turned all the way down. I realize that my old stove probably isn’t as air tight as it was when I bought it. But my cat just recently showed signs of being broken so at the beginning and middle of the season I wasn’t experiencing this problem. Now that I’ve bought the PE T5 I’m wondering how the long burns discussed here are achieved. It seems to me that there is a direct path to the stove pipe. What is happening inside the PE to: #1. Prevent the chimney draft from sucking in clean air and burning up the wood? and #2. How does the stove achieve such long burn times?

I'll give the short nontechnical answer and then someone can chime in and correct me when I'm wrong.
You are correct that the catalyst on your wood stove essentially acts a as a damper combined with the primary air. The small air passages combined with the friction of the air flowing across a material work to slow the draft down and create a pressure drop between the firebox and the chimney (temperature has an effect here also). Now while the PE T5 has no restriction between the fire box and the chimney it creates the same pressure drop air restriction in a different way using the burn tubes (baffle in the top of the firebox) as well as air flow pattern in the fire box.

When you are getting the stove going it is pulling the combustion air from the primary air inlet in the front of the stove this is the same effect as running you old Dutchwest with the bypass damper open, once the fire is going and a strong draft is started you begin to shut the primary air down. the fire then needs to get it's combustion air from somewhere so it begins to pull the combustion air from outside of the stove through the burn tubes and out the burn tube holes which are essentially an orifice/air restriction. The air flowing into the stove is then slowed down and superheated by the burn tubes as this air flow from the hole it ignites the smoke in the top of the fire box and ignites creating a pressure/temperature differential.

So essentially there is less control over your fire than a catalytic stove because the amount of air pulled through the burn tubes is directly correlated to how hot the fire is and how well your stove is drafting. Your flue temps will be slightly higher with the PE than you saw on your old Dutchwest stove and that causes many people to say that catalytic stoves are much more efficient. I have run a few Math CAD models (I'm still working on my models) with my old flue temps and my new flue temps and have essentially found it to be fairly similar as my new flue temps are higher for a shorter period of time and my old flue temps were lower for a longer period of time. Essentially there are only so many btu's in a piece of oak and its just a function of the time and temperature at which the btu's are released. I have noticed on every load of wood that I have burnt on my new stove that the secondary's light off much quicker than my previous cat stove however at times I have also found myself thinking the stove seems to burn quicker initially during the burn than my old stove. The odd thing is even on partial loads I still don't have to restart the fire in the morning so I'm not to concerned.
 
gogreenburnwood said:
Now that the cat in my DW stove is broken into pieces, I can’t keep a fire for more than a couple of hours. It’s been staying cold here especially at night, so I load it up as normal and in the morning there aren’t even any coals left to start another fire. I’ve always believed the honeycomb in the cat acted like a torturous path (or flue damper) that kept the supply air in check, providing a nice long fire when turned all the way down. I realize that my old stove probably isn’t as air tight as it was when I bought it. But my cat just recently showed signs of being broken so at the beginning and middle of the season I wasn’t experiencing this problem. Now that I’ve bought the PE T5 I’m wondering how the long burns discussed here are achieved. It seems to me that there is a direct path to the stove pipe. What is happening inside the PE to: #1. Prevent the chimney draft from sucking in clean air and burning up the wood? and #2. How does the stove achieve such long burn times?

Cert pretty well described the mechanics. The only thing I would add is "burn time" and sufficient btu output are two different things. and the latter would really depend on the btu demand of your home.

A proper chimney and dry wood will allow you to choke down on the primary air to extend the burn time.
 
madison said:
gogreenburnwood said:
Now that the cat in my DW stove is broken into pieces, I can’t keep a fire for more than a couple of hours. It’s been staying cold here especially at night, so I load it up as normal and in the morning there aren’t even any coals left to start another fire. I’ve always believed the honeycomb in the cat acted like a torturous path (or flue damper) that kept the supply air in check, providing a nice long fire when turned all the way down. I realize that my old stove probably isn’t as air tight as it was when I bought it. But my cat just recently showed signs of being broken so at the beginning and middle of the season I wasn’t experiencing this problem. Now that I’ve bought the PE T5 I’m wondering how the long burns discussed here are achieved. It seems to me that there is a direct path to the stove pipe. What is happening inside the PE to: #1. Prevent the chimney draft from sucking in clean air and burning up the wood? and #2. How does the stove achieve such long burn times?

Cert pretty well described the mechanics. The only thing I would add is "burn time" and sufficient btu output are two different things. and the latter would really depend on the btu demand of your home.

A proper chimney and dry wood will allow you to choke down on the primary air to extend the burn time.

+1 "A proper chimney and dry wood will allow you to choke down on the primary air to extend the burn time"

I don't really have enough time in on this stove to know about NS vs EW loading or whether to bring the coals to the front or back when reloading. Maybe Madison can chime in here with his experience on how much it effects his burn time or just his normal procedure for reloading and setting the fire for overnight burns. I would say that bigger splits or rounds are also going to give you longer burns.
 
Fine, but there is more. The T5 is special in the non-cat stove world. The T-5 firebox is equipped with a linkage that partially shuts off the secondary air as you close off the primary air. All of the other non-cats only allow you to control primary air and leave the secondary wide open.

So the T5 is special in that you can actually cut off more air to the fire. Your chimney can only suck smoke out of the firebox at the same rate that you allow air to enter the firebox. Stoves have gaskets on the doors to make them airtight. If you cut that air supply way down then the chimney fails to suck much out of the box. It's not about friction or an obstruction between the fire and the chimney it is about creating a vacuum in the firebox.

The T5 will burn longer than the other non-cats. Approaching, almost, cat stove burn times. Trouble is that it is a pretty small stove.
 
High beam do you know where I can see a picture or a description of this on a t-5, I was told the summit had the same thing but it does not.
 
Highbeam said:
Fine, but there is more. The T5 is special in the non-cat stove world. The T-5 firebox is equipped with a linkage that partially shuts off the secondary air as you close off the primary air. All of the other non-cats only allow you to control primary air and leave the secondary wide open.

So the T5 is special in that you can actually cut off more air to the fire. Your chimney can only suck smoke out of the firebox at the same rate that you allow air to enter the firebox. Stoves have gaskets on the doors to make them airtight. If you cut that air supply way down then the chimney fails to suck much out of the box. It's not about friction or an obstruction between the fire and the chimney it is about creating a vacuum in the firebox.

The T5 will burn longer than the other non-cats. Approaching, almost, cat stove burn times. Trouble is that it is a pretty small stove.

Highbeam you are right, sorry I forgot to mention that about the T5. The T6 approaches it a little bit differently than the T5 by incorporating the EBT which isn't really the same thing. A vacuum is essentially a pressure differential/drop sorry for the confusion. The smoke or draft rising due to the heat flowing from hot to cold creates the pressure drop which pulls in more air. As stated earlier temperature has a lot to do with this also as the hotter the flue is the more it is trying to flow from hot to cold which creates more of a vacuum.
 
In the diagrams I found I did not see the linkage you guys speak of on the T-5, is it just not shown on the diagram, as they did not show the EBT on the T-6 either.
 
Highbeam said:
The T5 will burn longer than the other non-cats. Approaching, almost, cat stove burn times. Trouble is that it is a pretty small stove.

The T5 is a medium-sized, 2 cu ft stove. Roughly the same size as an Oslo and just a bit below the Heritage in size. The T4 is the smaller, 1.4 cu ft version of this stove. The T6 is the 3 cu ft version.
 
With our T5 we've gone as long as 12 hrs & reloading with a 300 deg stove top. Depends upon heating needs. Most days this past winter we were reloading every 8 hrs. All on mixtures of Honey Locust, Ash, Hackberry, & a little Oak
 
gasavage said:
With our T5 we've gone as long as 12 hrs & reloading with a 300 deg stove top. Depends upon heating needs. Most days this past winter we were reloading every 8 hrs. All on mixtures of Honey Locust, Ash, Hackberry, & a little Oak

That's downright respectable off of a 2 cubic foot fire box and you still had a 300 degree stove top temp awesome.
 
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