Most heat out of your stove???

Thats a good question. Being that a Pellet Stove can modulate its feed rate, the highest fan setting should be run in conjunction with highest feed rate setting. You could lower fan speed one notch and raise your output temp a few degrees, but this might be bad for your stove. Its not a fixed BTU output like a hot air furnace where you can play with fan speed to maximize heat transfer and dial in Delta-T across exchanger.

Many people will say fan is always on high to extract as much heat as possible. I agree with this except if you run on lower heat ranges. I guess it depends on the stove along with the fans ability to move air. Mine blows a major amount of air to the point it feels like its blowing cool air if i run it too fast vs heat setting.
Trial and error is the biggest and most important. Try it diff levels with the same heat setting to find the 'sweet spot'
It also depends on if the stove is in the basement vs sitting 8 feet from me as well..

On a Harman if you have the stove set at a high heat rate the fan will go on high as needed to cool off the stove, at least in the auto modes. Or else it will reduce heat output in other modes. I tend to run my fan on a mid speed to heat this house, if you need more warm air in outer rooms it can help to boost the fan speed. Along with a higher fan speed and higher heat setting of course come more pellet consumption. So experiment for your given situation. The XXV's I've seen in operation are capable of pretty high fan output, they can move a lot of air and more quietly than my P61's fan. Also compared with a P series Harman they depend on that fan for output, where a p also radiates quite a lot of heat. So I can't fully compare apples to apples here.

Can't speak for those million dollar stoves but my Englander will shut off the convection fan when the stove cools off and start it again when it warms back up. This only happens if I set the fan to the highest level while the heat setting is on 1 or 2 (usually when we go to bed). When I set the fan to the mid level or lower it will never cycle off on any heat setting.

With my drolet, I can see the exhaust temps and try to keep the convection fan speeds so that the exhaust temps don't fall bellow 155f. Otherwise you're just blowing cooled air in the room. I actually had a creosote problem when I was getting to know the stove. I was running the convection blower too hard on a lower feed. Cooled it off too much. But it's a 500cfm fan too.

Higher air flow will extract more heat. Even if your hand "feels" that the air is less hot, it contains more total heat. However, the law of diminishing returns applies as you add more flow (See chart).

I work with heat generating equipment that uses thermostatically controled variable fans. When the internal components are heating up, the fan speed goes up automatically to avoid overheating. That's all the proof I need!

Deromax said:

Higher air flow will extract more heat. Even if your hand "feels" that the air is less hot, it contains more total heat. However, the law of diminishing returns applies as you add more flow (See chart).

I work with heat generating equipment that uses thermostatically controled variable fans. When the internal components are heating up, the fan speed goes up automatically to avoid overheating. That's all the proof I need!

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Everything looks good on paper or on charts.. even tho the higher flows extracts more heat doesnt mean it is the best solution for every scenario.
I would rather send a little more heat up the chimney having the air flow adjusted to feel more comfortable sitting near it.

Deromax said:

Higher air flow will extract more heat. Even if your hand "feels" that the air is less hot, it contains more total heat. However, the law of diminishing returns applies as you add more flow (See chart).

I work with heat generating equipment that uses thermostatically controled variable fans. When the internal components are heating up, the fan speed goes up automatically to avoid overheating. That's all the proof I need!

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I'm no engineer by any means, but I feel like there is a big difference in cooling a piece of machinery for the sake of keeping in cool, and trying to extract heat for the sake of heating a space.

The original poster asked for maximum heating efficiency, not maximum comfort. Everyone can do as they wish. I do not run the fan at full myself as I don't like the increase in noise.

Cooling a machine and extracting heat from a stove is not the same.
If you run the fan on high so it cools the stove then you are not running it efficiently at all. Just means you will be turning the feed up more than you might need to vs lower fan speeds extracting less heat at lower stove temps.

rdubs20 said:

This is my first year with my xxv. I love it so far. I guess my question is...in order to get the most heat out of my pellets should I have the fan run of full blast? Does it really matter what speed I have the fan on? I'm guessing you would get the most heat per pellet with the fan set to high. What do you guys think?

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I would see if you can get a reading on your flue temperature. Run the stove at a temperature where you have the least amount of heat going out your flue. You should be able to tell what to set your fan at once you see your flue temp. Medium would be a good start unless you are running the stove on a low heat setting.

rdubs20 said:

Interesting argument...I guess I will have to play with the fan and keep the burn rate on stove temp vs room temp to get a better reading.

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The feed rate is another whole issue that runs around the forum with Harman. Possibly the most misunderstood setting at the forum actually. You will be asking about that along the way I bet ! What I'm going to say now should get you wondering. Do yourself a favor and set the feed rate between 3 and 4 and basically forget all the other numbers exist LOL.

Blowingsmokeupyourchimney said:

I would see if you can get a reading on your flue temperature. Run the stove at a temperature where you have the least amount of heat going out your flue. You should be able to tell what to set your fan at once you see your flue temp. Medium would be a good start unless you are running the stove on a low heat setting.

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Harman stoves regulate exhaust temperatures within given standards, there isn't a whole lot you're gonna do with that by altering fan speed but use a little more or less fuel. Turn the stove down too much and you won't heat the house but you will heat the flue ! In fact you can go into Stove Temp Manual ( Constant burn) below level 4 and the fan won't even run but heat the flue to the minimum Harman requirement. Safest stove on the planet, never have a creosote fire in your flue pipe, Harman won't let it run that cold.

I agree that medium fan is a good starting point.

I never go past the midway point with the blower...
always reminds me of Air conditioning in the car whereas it always feels colder when I keep the blower on lower speed.
On highest fan speed it doesn't seem to be as cold as I assume it's just blowing any and all the cold it can muster up never giving it time to get the coldest that it does on lower fan speed/// my take anyways...

Cedarjunki said:

Cooling a machine and extracting heat from a stove is not the same.

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Why not? You are trying to extract heat from a heatsink in both case.

Cedarjunki said:

If you run the fan on high so it cools the stove then you are not running it efficiently at all.

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You are not "cooling the stove more", you are keeping more heat in the house instead of throwing it out the flue. The ratio of heat produced VS the heat extracted is how they compute the stove efficiency. The actual fire don't care for where the heat goes.

If the flue is becoming too cool, then it's a bad stove design.

Tonyray said:

I never go past the midway point with the blower...
always reminds me of Air conditioning in the car whereas it always feels colder when I keep the blower on lower speed.
On highest fan speed it doesn't seem to be as cold as I assume it's just blowing any and all the cold it can muster up never giving it time to get the coldest that it does on lower fan speed/// my take anyways...

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I don't seem to have that problem with my P61, I can put it on high and get all the better heat up my stair well to the second floor but I don't generally need it is all. My P61 puts out plenty of heat on full fan speed, a bit loud though. But too you gotta run enough feed rate to make heat, some people around the forum try and cheat that with feed rates of 1 and 2.

alternativeheat said:

I don't seem to have that problem with my P61, I can put it on high and get all the better heat up my stair well to the second floor but I don't generally need it is all. My P61 puts out plenty of heat on full fan speed, a bit loud though. But too you gotta run enough feed rate to make heat, some people around the forum try and cheat that with feed rates of 1 and 2.

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yes.. I agree.... have to have enough feed pushin thru..

Deromax said:

Why not? You are trying to extract heat from a heatsink in both case.



You are not "cooling the stove more", you are keeping more heat in the house instead of throwing it out the flue. The ratio of heat produced VS the heat extracted is how they compute the stove efficiency. The actual fire don't care for where the heat goes.

If the flue is becoming too cool, then it's a bad stove design.

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Not going to argue about. Run yours how you please and ill do the same. Like i said i prefer Not to feel cool air blowing out of my stove in which makes me turn the stove up higher to eat more pellets to feel the heat.. not very efficient in that aspect as i already stated. If the stove is the basement it is one thing.. if its in front of you its another story . Either way you look at it it is trial and error. I am using my stove for Heat. Im not using the blower to cool off. Maybe it is a poor design, so be it. Im warm thats what matters

rdubs20 said:

This is my first year with my xxv. I love it so far. I guess my question is...in order to get the most heat out of my pellets should I have the fan run of full blast? Does it really matter what speed I have the fan on? I'm guessing you would get the most heat per pellet with the fan set to high. What do you guys think?

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Its more important to keep it clean so the convection tubes can do their work. If they start getting built up with soot you will blow the heat out the exh pipe.

Deromax said:

I do not run the fan at full myself as I don't like the increase in noise.

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High fan on a P stove is pretty darned loud.......

Dan

Pete Zahria said:

High fan on a P stove is pretty darned loud.......

Dan

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True but in my case I barely hear it from upstairs, so when we need it that's what I do. Not to mention that in the really cold weather the stove ramps itself up on high fan anyway. Around here I find weather has more affect on how the stove runs itself than any other factor.

alternativeheat said:

True but in my case I barely hear it from upstairs

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Mine is in the basement... it isn't quite 'jet engine like' upstairs... But you can certainly hear it..
But no louder, I guess, than my brother's FHA system at his place..
My hearing is approaching as bad as my eyesight though...


Dan

rona said:

Its more important to keep it clean so the convection tubes can do their work. If they start getting built up with soot you will blow the heat out the exh pipe.

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Just cleaned mine. They were really built up.