Englander stove pellet use

[Harvey Schneider]

Interesting ... I would have thought the slower the room air blower was set to, the hotter the stove surface would get, as it wouldn't be 'cooled off' as much as with a higher blower setting. So much for my (non-existent) knowledge of heat transfer! LOL I was apparently oblivious to the temperature differential between the two sides being so important. Thanks!

My unit doesn't have a choke plate at the bottom of the hopper ... but the original poster's 25-PDVC, likely does. Sorry for my postings creating a drift in the conversation ....

Pellet stoves aren't great at radiant heating, they just aren't hot enough and they don't have enough heated surface. On my 25 PDVC most of the surface of the stove is cool enough to touch even when the front corners are at about 300F.
Most of the heat transfer is by means of the convenction air. Running the stove with minimum convection means that the stove body is hotter, but so is the combustion air going out the vent. That means the efficiency is compromised.

 

[Dhosh]

Pellet stoves aren't great at radiant heating, they just aren't hot enough and they don't have enough heated surface. On my 25 PDVC most of the surface of the stove is cool enough to touch even when the front corners are at about 300F.
Most of the heat transfer is by means of the convenction air. Running the stove with minimum convection means that the stove body is hotter, but so is the combustion air going out the vent. That means the efficiency is compromised.

Very good .... It makes sense. the last thing we want is excessive heat going out the vent! I'll invert my thinking, ... and what you are saying matches the single setting change I made that DIDn't make sense to me before.!

 

[Dhosh]

Exit air temperature is a questionable parameter in evaluating a stove or it's performance. It is dependent on convection air velocity (actually; "mass / unit time" or "density x volume / unit time"), combustion air velocity, intake air temperature and combustion air temperature as well as cleanliness of both pathways. To a smaller extent it is dependent on barometric pressures and humidity since both affect air density.
We get the impression that we are being scientific when we measure all the parameters that we can, but it is meaningless if we don't control all of the parameters that influence the one we are measuring.

But, at least in my case ... isn't that the bottom line of what I'm looking for? It might not be good for rating the stove's efficiency or performance .. but don't I want to 'tune' things the best I can to get that temp in the range where I want it? I don't want to cook the stove, and run it too hot .. but, at least at times .. I will likely want as much heat out of it, as fast as I can, while being safe. I will usually want to be pushing that heat out, so much of it will loft up the stairwell. What stays in the basement, I'll be happy with too, as that will help keep the basement useable, as well.

 

[Harvey Schneider]

But, at least in my case ... isn't that the bottom line of what I'm looking for? It might not be good for rating the stove's efficiency or performance .. but don't I want to 'tune' things the best I can to get that temp in the range where I want it? I don't want to cook the stove, and run it too hot .. but, at least at times .. I will likely want as much heat out of it, as fast as I can, while being safe. I will usually want to be pushing that heat out, so much of it will loft up the stairwell. What stays in the basement, I'll be happy with too, as that will help keep the basement useable, as well.

There are variables that can significantly skew the readings you take. One example would be that on a cold day the floor air may be a few degrees cooler than the rest of the room. It should be expected that the convection output will be lower by approximately the same amount. Temperature can vary due to differences in the way fuel is feeding both pellet density and the quantity delivered by the auger. Competition for combustion air (if not supplied with outside air) by other appliances can change the rate of combustion. Even with an OAK prevailing winds can change the amount of air available for combustion.
At the very least, you should use a figure of merit based on convection blower setting multiplied by the difference in input to output temperature. It isn't quite right, but at least it makes an approximate adjustment for the mass of the air being heated. That is, if you decrease the blower speed, the volume of air will decrease and the temperature should increase, but their product should remain the same. This doesn't quite work because the blower setting vs volume of air isn't linear, also because the bigger the difference in temperature the greater the amount of heat transferred and also because as velocity increases turbulence increases and turbulence improves heat transfer.
I don't mean to make this overly complicated, but decisions based on bad data are bad decisions.

 

[Dhosh]

There are variables that can significantly skew the readings you take. One example would be that on a cold day the floor air may be a few degrees cooler than the rest of the room. It should be expected that the convection output will be lower by approximately the same amount. Temperature can vary due to differences in the way fuel is feeding both pellet density and the quantity delivered by the auger. Competition for combustion air (if not supplied with outside air) by other appliances can change the rate of combustion. Even with an OAK prevailing winds can change the amount of air available for combustion.
At the very least, you should use a figure of merit based on convection blower setting multiplied by the difference in input to output temperature. It isn't quite right, but at least it makes an approximate adjustment for the mass of the air being heated. That is, if you decrease the blower speed, the volume of air will decrease and the temperature should increase, but their product should remain the same. This doesn't quite work because the blower setting vs volume of air isn't linear, also because the bigger the difference in temperature the greater the amount of heat transferred and also because as velocity increases turbulence increases and turbulence improves heat transfer.
I don't mean to make this overly complicated, but decisions based on bad data are bad decisions.

"but decisions based on bad data are bad decisions"

Agreed ... I do computer/network/wireless support and run into this all the time .. get the client's skewed take and not getting the real answers, sometimes!

My range of testing will usually be over the course of a day or weekend, and will try to change just one setting at a time, and allow enough time for the the change to be realized. I still need to make permanent my venting, as well. PVC Combustion air intake pipe needs to be disassembled and glued, a 3' piece of horizontal exhaust vent pipe replaced with a 2', and all sealed up. Testing for now is just that, as (at least for the testing I did last night) temps have been pretty steady at 41F. I have another thermometer well away from the stove, for the ambient room temp. I want to make a bit of a spreadsheet to take as much into account as I can.

 

[Harvey Schneider]

PVC Combustion air intake pipe needs to be disassembled and glued,

PVC is not acceptable as an combustion air intake. The intake must be of a non-combustible material. The risk is that a back burn (loss of draft) could cause hot combustion gasses to exit through the intake. However unlikely that is, the consequences are unacceptable. Burning PVC releases HCl fumes. Flexible aluminum tube is the easiest and least expensive solution.

 

[Dhosh]

PVC is not acceptable as an combustion air intake. The intake must be of a non-combustible material. The risk is that a back burn (loss of draft) could cause hot combustion gasses to exit through the intake. However unlikely that is, the consequences are unacceptable. Burning PVC releases HCl fumes. Flexible aluminum tube is the easiest and least expensive solution.

Well ... guess it's a good thing it's not glued, then! ... I would have thought the building inspector would have said something. The destructions just say 'pipe' ... and 2" pvc was a perfect fit. So ... another assumption. :-( I believe the combustion fitting is a 90deg rubber elbow. I suspect that may not be kosher either, then. I'll have to get further under there to see what IT connects to. Thanks again!

 

[Harvey Schneider]

Well ... guess it's a good thing it's not glued, then! ... I would have thought the building inspector would have said something. The destructions just say 'pipe' ... and 2" pvc was a perfect fit. So ... another assumption. :-( I believe the combustion fitting is a 90deg rubber elbow. I suspect that may not be kosher either, then. I'll have to get further under there to see what IT connects to. Thanks again!

There are many threads on this forum discussing OAK connections. The best I have seen is a custom metal adapter from an automotive performance shop for about $5 and 3" aluminum flex hose from a big box store. Outside you should have some sort of bug/rodent blocker and finally, make sure that the termination is above your snow line.

 

[Dhosh]

There are many threads on this forum dicussing OAK connections. The best I have seen is a custom metal adapter from an automotive performance shop for about $5 and 3" aluminum flex hose from a big box store. Outside you should have some sort of bug/rodent blocker and finally, make sure that the termination is above your snow line.

I did have a screen in the 90deg drop at the end, and above snow line, and at least 3' from an operational window. I did the research on where and how to run... but not WHAT to run! I'll be looking tonight at the fittings, and will re-do this weekend!

 

[Pete Zahria]

Left side of stove as you look at it head on, 3 - 4 inches down from the top of the stove with one of these or a digital probe gun.

On low temp ranges, all of the magnet ones I have tried are never close to the IR gun..
Higher temps, seem closer. (higher in my case, on my coal stove @5-600°.)
I use it as a gauge, more than for accurate temps.
For that I use the IR gun..
I probly should fiddle with my settings more in the shop pellet stove, as 1-1 really is not
a whole bunch of heat on mine.. Of course it's also a garage too...
Dan

 

[Harvey Schneider]

On low temp ranges, all of the magnet ones I have tried are never close to the IR gun..
Higher temps, seem closer. (higher in my case, on my coal stove @5-600°.)
I use it as a gauge, more than for accurate temps.
For that I use the IR gun..
I probly should fiddle with my settings more in the shop pellet stove, as 1-1 really is not
a whole bunch of heat on mine.. Of course it's also a garage too...
Dan

I don't consider IR guns to be very accurate either. They are too dependent on the surface characteristics and most have too large a field of view to get accurate readings.
The best I have found for fast accurate readings is a thermocouple meter. With a wire thermocouple you can measure either the surface temperature or the air temperature with better accuracy than just about anything else available. Even the cheep Chinese meters on ebay are accurate to just a degree or two over an enormous range.

 

[SingledadMI]

Ok, not sure how this got to taking the temperature of the stove....but that's not what my issue was. I'm still trying to get a decent burn time out of my pellets. I'll adjust my choke plate to about 1/4 like the last fellla suggested and see how that works. I'd like to get a better idea of what my bottom adjustments should be at. I khnow

 

[Harvey Schneider]

Ok, not sure how this got to taking the temperature of the stove....but that's not what my issue was. I'm still trying to get a decent burn time out of my pellets. I'll adjust my choke plate to about 1/4 like the last fellla suggested and see how that works. I'd like to get a better idea of what my bottom adjustments should be at. I khnow

Start out with them at the original settings. If the fire burns out (most of the pellets burned) increase low fuel feed. If the fire goes out (pile of unburned pellets left) increase low burn air and decrease low fuel feed. Make small adjustments and wait for everything to become stable before you make another adjustment (15-20min). If the fire looks smokey increase low burn air.
Once you get it to the point where it will idle smoothly, you can do a measured burn. Take a know weight of pellets (a few pounds) and measure how long it burns. Then calculate how long the 40 lb bag would have burned by taking the proportions 40lb burn time = (40 / weight burned) x burn time of sample.

 

[Pete Zahria]

I don't consider IR guns to be very accurate either. They are too dependent on the surface characteristics and most have too large a field of view to get accurate readings.

That may be true... but when I use mine on the stoves, I use the exact same spot on the stove,
and hold it the same distance each time...
Even if it is off 1-2%, for comparing one brand of pellet to another, or one setting to another,
I am getting a lot more accurate reading than my 9 dollar magnet stick on... for comparing changes.
We checked three different laser guns just for the heck of it one day and they were all within 3°.
For un-scientific testing, that seems close enough..
(imo, of course)

Dan.

 

[Pete Zahria]

Ok, not sure how this got to taking the temperature of the stove....but that's not what my issue was.

Might not have addressed your consumption issue,
but at some point you may want to know not only how much you are burning,
but how well.......
You can't know that without doing a little more detailed monitoring.
It's possible to burn more pellets and not get more heat..
Like having a car with a carb.. using more fuel, but getting less horsepower..

Dan