Room air convection fan

[cobra]

A question for those with far more experience than me...

I own a Breckwell P2000 and have never been happy with the room convection blower.

My theroy is that if the air is "hot" hot coming out the tubes, then we need to flow more air to cool them more and thus suck more heat out ot the stove instead of the "extra" heat going up the chimney.

What is the biggest cfm blower I could install that would bolt up so I can experiment on my theroy ?

ie... I think I would takle 500cfm at 100 degrees over 350 cfm at 120 degrees !

What are your thoughts ?

Thanks in advance.

 

[kinsmanstoves]

A question for those with far more experience than me...

I own a Breckwell P2000 and have never been happy with the room convection blower.

My theroy is that if the air is "hot" hot coming out the tubes, then we need to flow more air to cool them more and thus suck more heat out ot the stove instead of the "extra" heat going up the chimney.

What is the biggest cfm blower I could install that would bolt up so I can experiment on my theroy ?

ie... I think I would takle 500cfm at 100 degrees over 350 cfm at 120 degrees !

What are your thoughts ?

Thanks in advance.

The circulation blower in a P-2000 is around 200 cfm I do not have a manual in front of me at the house. You have something else not right from what little you described.
Call me if you can I will be at the store all morning
Eric
330-876-0200

 

[MCPO]

A question for those with far more experience than me...

I own a Breckwell P2000 and have never been happy with the room convection blower.

My theroy is that if the air is "hot" hot coming out the tubes, then we need to flow more air to cool them more and thus suck more heat out ot the stove instead of the "extra" heat going up the chimney.

What is the biggest cfm blower I could install that would bolt up so I can experiment on my theroy ?

ie... I think I would takle 500cfm at 100 degrees over 350 cfm at 120 degrees !

What are your thoughts ?

Thanks in advance.

The amount of hot air extracted from the heat exchanger and distributed is hopefully designed to some degree of efficiency and balance within each stove brand. Fan speeds / volume of air has to be somewhat proportional with heat settings for obvious reasons. That said , I have modified my own Harman stove to have the fan run constantly vs cycling on/off at the lowest setting of #1.
I think there can be some latitude applied to this issue as most pellet stoves do appear to be rather crudely designed to begin with and not a whole lot of high tech engineering or advancements put into the newer models either.
With regards to the Harman the heat exchanger is about as simple as it gets. I think my wife could have come up with a better design

 

[cobra]

Sorry for any confusion... my temps and cfm figures were examples only..

My pellet stove is working great... but I think they are still very inefficient.

Say my heat exchanger tubes are at 300 degrees... without convection air, and by placing convection air through the tubes it only cools them to 250 degrees.

In reality....am I really losing the extra energy (250 degrees) up the chimney ??

Imagine the tubes being cooled to 150 degrees by more air.....I am now pulling 150 degrees from the stove..not 50 degrees??

I am not worried about creosote since I am still burning in the burn pot at a high tempreture.


Maybe I have this wrong ??

 

[peirhead]

Most OAK inlets on the stoves provide air to the convection blower (not the combustion side)...If you are trying to boost the air through the convection side you could rig up some fan assembly to push more air into the OAK inlet....If you already have the OAK connected to an outside source it probably isn't worth trying to pressurize it from outside though!!

 

[MCPO]

Most OAK inlets on the stoves provide air to the convection blower (not the combustion side)...If you are trying to boost the air through the convection side you could rig up some fan assembly to push more air into the OAK inlet....If you already have the OAK connected to an outside source it probably isn't worth trying to pressurize it from outside though!!

I think you ought to rethink what the OAK is for and exactly what it supplies air to.

 

[MCPO]

Sorry for any confusion... my temps and cfm figures were examples only..

My pellet stove is working great... but I think they are still very inefficient.

Say my heat exchanger tubes are at 300 degrees... without convection air, and by placing convection air through the tubes it only cools them to 250 degrees.

In reality....am I really losing the extra energy (250 degrees) up the chimney ??

Imagine the tubes being cooled to 150 degrees by more air.....I am now pulling 150 degrees from the stove..not 50 degrees??

I am not worried about creosote since I am still burning in the burn pot at a high tempreture.


Maybe I have this wrong ??

You`re not going to make much improvement no matter what you do. If you increase the air flow you will decrease temperature of air coming off the heat exchanger unless you increase the pellet feed rate.
Adding a more powerful fan would only add cost of wattage to force more air thru an already restricted air flow path and also increase the noise substantially.
As I said before there is an inherent balance in the design itself that limits the amount of heat that can be extracted off the exchanger . You want more heat ? Increase the pellet burn rate.

 

[peirhead]

Gio...not all stoves use the OAK for combustion air!... some use it for convection air supply (including some of the Quad units) I'm not sure about the Breckwell though.

 

[MCPO]

Gio...not all stoves use the OAK for combustion air!... some use it for convection air supply (including some of the Quad units) I'm not sure about the Breckwell though.

Does it make any sense to bring in cold air (OAK) just to send it through the heat exchanger? (distr. fan)I`d imagine it would needlessly use considerably more energy.
However I`d like you to explain more or let me know exactly if and what I`m missing here.

 

[peirhead]

in the early 80s Heatilator (I think) had a fireplace they advertised as the "Pressurizer" the idea was to bring in outside air through the heat exchangers in the stove and blow it into the room..the airflow through the heat exchanger was greater (typically) then the combustion air the stove used from the room...hence increasing the pressure in the house.. The idea was instead of cold air coming in through the cracks, warm house air would actually be trying to get out of the house through the same cracks....supposedly there were no cool drafts, but I think it fell from favour because of moisture buildup in the walls...this was prior to current HVAC standards.

Some stoves (most Quads anyways) use a similar principle however I have since read that most Harmans use the OAK strictly for combustion air...obviously manufacturers have taken up sides on this issue and it gives us another OAK bone to chew on!!

 

[cobra]

[
Gio, maybe I have this wrong.. buuuuutttt.. if the heat from the stove without any convection air at all is a set tempreture ( wood only burns so hot..and the distance to the heat tubes is a constant).... with no cooling at all, the heat tubes would eventually get to a certain temp. and remain there for any given amount of fuel /oxygen used.

At that time, where do you think the extra energy goes ????? thats right..straight up the chimney.....

Using that logic.... it tells me that unless we supply enogh air that we eventually cool the tubes to room temp. then we are wasting energy up the chimney !



Maybe smaller burn pots, closer to the heat tubes is the answer... I know my center tubes are much hotter than my outer tubes...




quote author="Gio" date="1228500901"]

Sorry for any confusion... my temps and cfm figures were examples only..

My pellet stove is working great... but I think they are still very inefficient.

Say my heat exchanger tubes are at 300 degrees... without convection air, and by placing convection air through the tubes it only cools them to 250 degrees.

In reality....am I really losing the extra energy (250 degrees) up the chimney ??

Imagine the tubes being cooled to 150 degrees by more air.....I am now pulling 150 degrees from the stove..not 50 degrees??

I am not worried about creosote since I am still burning in the burn pot at a high tempreture.


Maybe I have this wrong ??

You`re not going to make much improvement no matter what you do. If you increase the air flow you will decrease temperature of air coming off the heat exchanger unless you increase the pellet feed rate.
Adding a more powerful fan would only add cost of wattage to force more air thru an already restricted air flow path and also increase the noise substantially.
As I said before there is an inherent balance in the design itself that limits the amount of heat that can be extracted off the exchanger . You want more heat ? Increase the pellet burn rate.[/quote]

 

[MCPO]

in the early 80s Heatilator (I think) had a fireplace they advertised as the "Pressurizer" the idea was to bring in outside air through the heat exchangers in the stove and blow it into the room..the airflow through the heat exchanger was greater (typically) then the combustion air the stove used from the room...hence increasing the pressure in the house.. The idea was instead of cold air coming in through the cracks, warm house air would actually be trying to get out of the house through the same cracks....supposedly there were no cool drafts, but I think it fell from favour because of moisture buildup in the walls...this was prior to current HVAC standards.

Some stoves (most Quads anyways) use a similar principle however I have since read that most Harmans use the OAK strictly for combustion air...obviously manufacturers have taken up sides on this issue and it gives us another OAK bone to chew on!!

Well! I`ll be. I would not have imagined this to be but then again I learn something new every day.
Thanks for enlightening me.

 

[cobra]

I had more time to experiemnt today ahd here are the findings:

All temps measured using master cool infrared thermometer with laser pointer

Running my P2000 on "3" on the front edge of the tubes was 430 F

The heat in the exhaust was 215 F

Tempreture on thermometer across the room was 75 F

I am not sure of the CFM of the convection blower on "3"

I turned on the fan overide ((makes it go to its highest speed, but I don't know thoes CFM either) left it for 45 mins... here are the results

the front edge of the tubes was 360 F

The heat in the exhaust was 205 F

Tempreture on thermometer across the room was 78.4 F

Now if only the pellet manufacturers would get a clue.. I am sure we could have far more efficnet stoves made...

 

[peirhead]

Ok I feel stupid...I should wait till I actually have a stove before I comment on it. After re-reading the Quad Castile manual it does appear the Outside air feeds the combustion side..not the convection side...so no you don't want to try pressurising the outside air inlet....I guess my mind is still lost in the 80s when I installed a clone of a "Pressurizer" zero clearance fireplace which pushed outside air through the heat exchanger (and worked very well by the way)