Why are room blowers so small?

[skibladerj]

Why is it thar pellet stove room blowers are so small? When tou look at most larger solid fule burning units the y have roughly 100 to 65cfm per btu. I have heard it has to do with the temp un the burn chamber but... if a unit could produce 100k btu with a 1000cfmfriend room fan why is my stove rated at 48k btu with only a 120cfm fan?

Food for thought?

 

[hyfire]

This is why i picked my stove(eco-65) , it has a 500 cfm rating. Only a few other stoves are comparable in cfm rating. I;m not sure why the other stoves are so low, maybe people didn;t like the noise factor.

 

[skibladerj]

That is the only thing i can think of too.

 

[Mt Bob]

1 stove is a space heater,belongs in an insulated room,sized properly.2 heat removal from stove has to not cool down stove too much,inefficent burn happens,stove plugs up.3 some stoves are more for just a little heat,not to be heard,just seen,why some harmans have fireplace mode,and some are for quick heat,like your eco.Just for info.for years a lot of european stoves had no blower,relied on natural convection,properly sized for the room.Now their regulations are strict,they have blowers as it makes the stove test more efficient.I do not think you can compare different fuel types,and different stove designs,with btus to cfms.Personally I prefer steady constant low heat,minimal noise.Guess I grew up in too many houses that had a coal stove or steam radiators.

 

[skibladerj]

It was merly a observation... but i wish stoves had higher cfm output.

 

[Mt Bob]

It was merly a observation... but i wish stoves had higher cfm output.

Sometimes it would be nice!Hyfire probably has about the highest volume,you may have to change stoves!

 

[skibladerj]

Sometimes it would be nice!Hyfire probably has about the highest volume,you may have to change stoves!

Yeah thats why im going back to coal

 

[hyfire]

Actually the Fahrenheit 50f pumps out 800 CFM, but its a furnace....

(broken link removed to http://www.fahrenheittech.com/corn_stove_specifications.html)

 

[jlupi]

higher cfm = louder and cooler air coming out.

 

[peirhead]

Higher CFM also means more air current of cool air towards the stove along the floor....like a breeze!! It may actually make you feel colder

 

[Pete Zahria]

Some people don't like having a jet engine running while watching tv..

Dan

 

[don m]

Just curious - why would you want greater airflow from a non-ducted appliance? The heat exchanger doesn't appear to be set up for good heat transfer at high cfm operation. Just my thoughts, but I would think that you would want more heat exchanger surface at a cfm rating that much higher, or you may just get mostly blow-by. But hey, I could be all wet.......don

 

[skibladerj]

My stoves ugly and in my "basement" i have a bi-level. So the sound dose not make a difference. Like i said it was observation. Most stoves are in the low 100's some are in the 200's not not much more after that until you get to furnace level 800-1100cfm level. Granted exceptions are out there too.

 

[hyfire]

The enviromaxx and maxx M both also have 455 CFM blowers.

http://enviro.com/products/catalogue/product/?prod=MAXX-1

 

[peirhead]

One of the modifications I'd like to see on my Quad would be a variable speed override on the convection fan, so you could turn it up while still running at lower settings....sometimes when running on low I'd like to have the convection fan on Med, and similarly when on Medium sometimes I'd like to be able to have the fan operate on High...The variable speed would let me tune it for noise level if I am in the room.

 

[stovelark]

Hi peirhead- I agree, but most mfrs like the simplicity of convex controlled to match heat level burning, that leads to proper stove operation (so heat level 1 and fan level 5 stripping heat away and stove being cool doesn't allow to be available). On some analog stoves (Nap, some enviros, some older stoves) the convex blower is independent of feed rate. The Quad CB1200 FS has separate fan and heat level settings (hi/lo fan for each heat level lo/med/hi) Love that feature too.... One could always put a var rheostat in line with their convex blower, but I'm not an advocate to modify any stove.....good luck

 

[Mt Bob]

I have always thought the integras were too slow and was going to change mine,but after a lot of years have done nothing,so must not be that important to me!

 

[SwineFlue]

One could always put a var rheostat in line with their convex blower, but I'm not an advocate to modify any stove.....good luck

That would allow you to run it slower than Quad's default. Running the blower faster would be more difficult. The best method I have found is to run it on the higher setting with the feed gate closed down.

 

[SwineFlue]

Hi peirhead- I agree, but most mfrs like the simplicity of convex controlled to match heat level burning, that leads to proper stove operation (so heat level 1 and fan level 5 stripping heat away and stove being cool doesn't allow to be available). On some analog stoves (Nap, some enviros, some older stoves) the convex blower is independent of feed rate. The Quad CB1200 FS has separate fan and heat level settings (hi/lo fan for each heat level lo/med/hi) Love that feature too.... One could always put a var rheostat in line with their convex blower, but I'm not an advocate to modify any stove.....good luck

You mentioned the new Mt Vernon E2 in another thread (thanks for the head's up!). I just took a look through the manuals for it... the control board uses exhaust speed and temperature sensors to vary the convection blower speed. (No snap disk for the convection blower.) It's not user selectable, but I think it's an improvement.

 

[Snowy Rivers]

THE OLD QUAD 1000 WILL HANG THE CURTAINS OUT A FLUTTERING.

PLUS THE HEAT WILL SCORCH THE HAIR ON YOUR ARM TOO.

Small ???????????

 

[chken]

Why is it thar pellet stove room blowers are so small? When tou look at most larger solid fule burning units the y have roughly 100 to 65cfm per btu. I have heard it has to do with the temp un the burn chamber but... if a unit could produce 100k btu with a 1000cfmfriend room fan why is my stove rated at 48k btu with only a 120cfm fan?

Food for thought?

I'm no stove engineer, but I think they size blowers for the stove's output. The amount of max BTUs you're getting out of your stove is not based upon your fan speed. You have to burn about 2x the pellets to take a 48k btu stove and turn it into a 100k btu stove, not just turn up the fan.

The reason why they don't put 1000cfm fans in a 48k BTU stove is that it would probably cool the exhaust too much. Cold exhaust leads to condensation issues, creosote issues, etc.

 

[skibladerj]

I'm no stove engineer, but I think they size blowers for the stove's output. The amount of max BTUs you're getting out of your stove is not based upon your fan speed. You have to burn about 2x the pellets to take a 48k btu stove and turn it into a 100k btu stove, not just turn up the fan.

The reason why they don't put 1000cfm fans in a 48k BTU stove is that it would probably cool the exhaust too much. Cold exhaust leads to condensation issues, creosote issues, etc.

My OP didnt really have anything to do with turning my stove into a 100k btu stove or putting a 1000cfm fan on it. I was merely showing the correlation of stove btu's to CFM fan speed of larger units. As my only supporter 'hyfire' has help point out a few companies do put larger blowers in their units.

 

[chken]

My OP didnt really have anything to do with turning my stove into a 100k btu stove or putting a 1000cfm fan on it. I was merely showing the correlation of stove btu's to CFM fan speed of larger units. As my only supporter 'hyfire' has help point out a few companies do put larger blowers in their units.

Anyone willing to take the time to read your post and give you a thoughtful response is a "supporter".

As for your correlation, I think I agreed, as I said, "they size blowers for the stove's output".

I assumed your final "food for thought" comment was related to the notion of putting in a larger fan. Your example was 1000cfm for 100k btu, and your stove was 120cfm for 48k btu. Presumably, you were thinking of keeping that cfm to btu ratio and wondering if a 480cfm fan would make sense. Foolish me for trying to help. Since your OP didn't "have anything to do with" that, then just ignore my comment.

 

[Arti]

A Gas Furnace has a higher rating on CFM rating because it needs to push heated air a longer distance, also the return air path is a lot more restrictive than a freestanding stove. ( Think about trying to drink a milk shake thru a 50 foot straw !!)
While a furnace generally has a higher capacity blower it doesn't operate at full speed , The blower speed is set at a specific heat rise and not at a particular cfm.
IE if the cold air entering the Furnace is 70 degrees and leaves at 110 degrees then it is said to have a temp rise of 40 degrees.

Most condensing furnaces operate somewhere between 30 to 60 Degrees of temp rise, this keeps the unit not only from overheating but also prevents condensation of flue gas in the primary heat exchanger. To little heat in a gas furnace is as harmful as getting it overheated.

Also pellet burners provide 2 types of heat, 1 is convection (Heated Air blown from unit) the second is Radiant (Flows from the surface and is radiated into the room, this is like the heat you feel if you put your hand near the glass on a pellet stove.) Any radiant heat from a Gas Furnace is lost in a basement or utility room so it is of little value.

The higher CFM speeds on a Furnace are usually used for residential Central Air Conditioning. 400 CFM per ton of cooling is considered average so a 2.5 ton A/C unit needs the furnace blower set at 1000 cfm to work reasonably efficiently. Therefore a higher rated fan is required in a basement dwelling furnace to meet the cooling demands more than the heating load.
As a side note most Gas free standing parlor heaters use blowers very similar in size compared to what is used in our pellet burners.
Just my 1.5 cents worth...