Does Lower Fan Speed = Less heat?

Status
Not open for further replies.

heb80

New Member
Feb 14, 2008
25
Harrisburg, PA
If I turn the fan down on my pellet stove would I effectively be wasting heat?

In other words, If my feed is set to 3, am I going to get the same efficiency whether my fan is set to 3 or 9?
 

petejung

New Member
Sep 28, 2007
212
I may be wrong on this one... I don't think that your room blower speed has any effect on how efficiently the pellets get burned - that would be more related to the combustionexhaust blower.
 

schulj76

New Member
Dec 21, 2007
2
Cen. IA
I think the question pertains to heat transfer via convection blower. Do you get more heat in the room with the fan on high vs out the exhaust with it on a lower speed. Think of the tubes as a giant heat sink, the more air that moves through them the more heat would be absorbed by them to try to balance the ambient temperature in them. I run mine on the higher speeds if I have the fire to support it. I may be wrong, I have before.
/Frac
 

jmlarson

New Member
Dec 17, 2007
34
Central, PA
I agree...the convection van or (room fan) is simply that. It forces the air out of the unit at a higher rate. If this fan was to fail the unit would still produce heat...it would just be more of a radiant unit. No way to force the air from the unit. If this makes any sense....if i am wrong feel free to correct me.
 

staplebox

Member
Jan 2, 2008
211
Eastern CT
I am not sure if your premise is true, but I believe it is. I usually run the stove at a 1-7. I know that the same heat/energy is produced as would be at a 1-2 setting but I am not sure where that heat goes. I want to do everything I can to get it into the house.
 

MButkus

Feeling the Heat
Feb 4, 2008
253
Jersey
At a higher circulation fan speed, more air is being displaced at the same feed (heat) setting so more of the room is heated. Sort of like a fireplace. On low fan, it's warmer by the stove. A higher fan heats more of the room at a lower temperature.
That sound right?
If it's warm out (40-50) I put the circulation fan at 1 and heat at 1. I guess you are losing heat, but you can't go below heat #1.
 

stoveguy2esw

Minister of Fire
Fractured said:
I think the question pertains to heat transfer via convection blower. Do you get more heat in the room with the fan on high vs out the exhaust with it on a lower speed. Think of the tubes as a giant heat sink, the more air that moves through them the more heat would be absorbed by them to try to balance the ambient temperature in them. I run mine on the higher speeds if I have the fire to support it. I may be wrong, I have before.
/Frac

fractured is correct in essence , im going to expound on it some , the relation is heat transfer rate v/s air movement rate; bear with me the math may not be dead on as im using examples that do not have calculations ofr accuracy but for principle of operation it will make some sense.

take a stove which when the air that is blown from it is moving at 10 cfm and the temp is 150 degrees now that would denote a higher heat transfer rate as the air is in the stove for a relatively longer time, increase the air moving out to say 20 cfm the temp of the air will drop as the air is not in the stove as long, but if the air temp only drops a few degrees and you get twice as much , does that not translate to a higher overall gain? now take our stove and max the blower , the temp fals off a large amount , volume may be way higher but the loss in temp may be greater than the volume gain, this would be where the air outruns the heat transfer and the transfer efficiency would drop in this case it is also possible that the cooling effect outruns the transfer in the metal tubes , meaning that the fire cannot keep up with the air's removal of heat , and the result would be a drop in efficiency. i routinely run my 25-PDVC at a much higher blower speed than heat range as it works well for my application , but ive found that too high a blower spped and too low a heat range doesnt heat as well for me as if i keep them a few steps closer, my ratio is usually h/r 1 b/s 6 then 2-7 and 3 or higher -9 if i run at 1-9 i do not get as much heat, probably due to my explanation above.

good topic though
 

cntbill

Member
Jan 18, 2008
153
Reading PA Area
www.cnt-web.biz
My theory and its just that, looking from a BTU, heat transfer standpoint, moving heat from one place to the other. If the given BTU out put is such, and the air flow is another at some point in time the two will be the same.... But that would be in a sealed environment, so now we have to deal with heat loss, thermal and air, new colder air in and heated air out. So in essence we don't want to cool the transfer tubes with new air to a degree it is less, lowering the efficiency of heat transfer... OK.. maybe I just rambling, but I know my 25-PDVC if set at H 1, B4, or 4-6 works the best for me.
 

pelletizer

Minister of Fire
Jul 17, 2008
663
Pellet County N.H.
Been a while since this thread was posted against, I am running my PDVC now at H-4 F-5 I just bumped it up the fan to 6 to pull more heat form the stove.
Is it ok to bump up the fan even higher? thx.
 

staplebox

Member
Jan 2, 2008
211
Eastern CT
Room blower higher than feed can't do anything bad. The other way around is bad.
I run 1-6...2-8...and 3-9. Thats pretty much all I use. I spent last winter with various thermometers set up around the stove. I don't remember the details but I wrote down those to use for this year.

So you should try 4-6, 4-7, 4-8 and 4-9 and see what you get. A question in this thread is 'can you blow room air so hard that you don't allow for efficient heat transfer'. At some speed the answer has to be yes, but I haven't found that 3-9 is too fast.
 
Status
Not open for further replies.