CFT (covection fan threshold)

CFT (covection fan threshold)

PostBy: AKHEARTH On: Tue Oct 28, 2008 10:02 am

I was wondering if there is a method to determine what the CFT should be set at to get the maximum efficiency out of my stove? I have a AK Kodiac hearth model, Coal-trol with T2 thermostat in my basement. It seems like the covection fan is always running and it is only blowing out luke warm air.
Thanks.
AKHEARTH
 
Stoker Coal Boiler: EFM 520

Re: CFT (covection fan threshold)

PostBy: morrisfamily3098 On: Tue Oct 28, 2008 11:56 am

EXPERIMENT. i have experimented using the surface temp of the stove, the air temp output (convection) and the stove pipe temp (core) and tried to keep as much heat inside as possible. i also am going to purchase a heat reclaimer that goes in the stove pipe. the come on at 160* and go back off at 130*. i have checked my stove at 130* and it pulls a constant .02 draft at an outside temp of about 35*F. my CFT is set on 15 right now on a hyfire II running only one side. at start up i am getting about 100* air with the blowers on low
morrisfamily3098
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: Hyfire2

Re: CFT (covection fan threshold)

PostBy: WNY On: Tue Oct 28, 2008 12:55 pm

I think mine is set at 6 or 8.
if you read the threads on teh heat reclaimers, most don't do much on the coal, since the exhaust temp is so low. But some do use them.
WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: CFT (covection fan threshold)

PostBy: AKHEARTH On: Tue Oct 28, 2008 3:44 pm

Thanks to both of you for your input. I will see what I could come up with. Mine is currently set on 15 also.
AKHEARTH
 
Stoker Coal Boiler: EFM 520

Re: CFT (covection fan threshold)

PostBy: pvolcko On: Wed Oct 29, 2008 5:38 pm

There is no official "best" method for setting CFT. The shipping value should be good for most stoves, but some (Keystokers in particular) benefit from a higher setting. It is really a personal preference thing.

If it is blowing lukewarm air then you may want to increase the CFT setting. Also, based on the other thread, you may have a MAX setting issue (I gave instructions on how to fix it) and a general air circulation issue that needs to be addressed before trying to get too finicky with the CFT setting.
pvolcko
 

Re: CFT (covection fan threshold)

PostBy: AKHEARTH On: Thu Oct 30, 2008 9:00 am

Should the convection fan run all the time? Mine seems to run pretty much at max speed continuously. I would think it should shut down to allow heat to build up in the stove and then kick on when it gets to a certain temperature.
AKHEARTH
 
Stoker Coal Boiler: EFM 520

Re: CFT (covection fan threshold)

PostBy: WNY On: Thu Oct 30, 2008 9:52 am

It should only run based on the FEED rate, check your MAX setting and your temperature settings. Most of the time, I don't even hear my fans running, they run 20-40%, but you can really feal the the heat.

ALso, make sure you have it plugged into the "CONVECTION" FAN outlet on the Coal Trol.
WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: CFT (covection fan threshold)

PostBy: AKHEARTH On: Thu Oct 30, 2008 12:46 pm

Thanks WNY. Could you please elaborate on what you mean by it running based on feed rate? My current min and max is 5 and 30. 30 gives me hot ashes about 1-1/2" from the edge of the grate. My feedrate varies from 99 the highest to the lowest I've seen was I think 76.
AKHEARTH
 
Stoker Coal Boiler: EFM 520

Re: CFT (covection fan threshold)

PostBy: WNY On: Thu Oct 30, 2008 1:01 pm

That is probably why the fans run all the time, when the feed rate goes up (0-99), the fans should compensate, the higher the feed rate, the higher the fans. If you have only seen it as low as 76, then you may have to raise your Max Feed or lower the thermostat setting until it reaches room temp and start from there. Make sense?

if your setpoint is always higher then the room temp can reach, it will keep feeding until satisfied. So, the feed rate may stay high. My feedrate drops to 0 when no heat is required (temp 70 = Room Setpoint of 70), Soooo, if your setpoint is 75 and the stove can only get it to 72 or 73, the feedrate will continue to rise and the blowers keep increasing to satisfy the temperature.

Therefore, The stove is too small to maintain a nice even temp (Drafty house, windows, no insulation...etc.)
The Thermostat is too far away from the heat source
The Max setting need to be bumped up a few points at a time to get more heat out of the stove without pushing hot coals off the end.

Keep us posted, we will get it working.!!
WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: CFT (covection fan threshold)

PostBy: mjwood0 On: Thu Oct 30, 2008 3:37 pm

I had a bit of trouble understanding this at first too. This is what finally made it click for me.

Think of the feed rate as a percentage. 0% - 99%. You're currently running between 76% and 99% of max output capacity for your stove.

Think of the min and max as the feed rate. If you have them set at 5 and 30, that means that at 99% you're feeding at rate 30 and at 0% you're feeding at rate 5.

So... if you're never seeing the feed rate going lower than 76%, it means that if it gets much colder, your stove won't keep up. The other problem could be that you're not efficiently transferring the heat the stove is making to the area where the thermostat is located. Either way, it sounds like adjustments need to be made.

To give you an idea, my LL Econo runs between 0% and 5% most of the day when the weather is above freezing and there is sun during the days (good window location). As long as the temps hover around freezing or so, it doesn't rise much above 20%. In the really cold (-20 F) and windy nights we sometimes get, the feed rate got as high as 94%. My glowing embers were about 2 inches from the end of the grate.
mjwood0
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: Econo

Re: CFT (covection fan threshold)

PostBy: AKHEARTH On: Thu Oct 30, 2008 3:48 pm

I understand what you are saying. I had the call for temp the same as the room temp but maybe when I didn't notice, the room temp dropped a degree and it started calling for coal again so the feedrate stopped dropping. As you stated maybe my max needs to be higher to get the core temp of the stove up.

If you don't mind I have another question. It probably should be on a different forum but what the heck.
If I was to remove my barometric damp. how much heat would I lose through my chimney? I currently have about a 6' piece of flex stainless pipe going from the stove up into the flue.

Thanks.
AKHEARTH
 
Stoker Coal Boiler: EFM 520

Re: CFT (covection fan threshold)

PostBy: WNY On: Thu Oct 30, 2008 8:00 pm

Sounds like you are figuring it out, you may have to go 2-3 degrees below room temp to see if the stove will cool down and the fans slow down and/or stop. Check you setback settings too, I wouldn't go more than a couple degrees if at all. I keep mine with 1-2 degrees of each setting, so there no big changes to have to overcome. Better to run a constant temp then up and down all the time.

The baro is to limit and control the draft on the stove, depending on your situation and the draft of our chimney, sometimes you may not need it. It just helps reduce air coming thru the stove. Without it, could pull more air thru the stove which in turn and make it burn hotter and loose heat up the chimney, how much? depends on the draft of your chimney. if you have a short chimney, you may not have a lot of draft there the baro may not make much difference, a taller chimney - a lot more draft.

I couldn't really tell you how much you would loose, every heating situation is different. Our chimney is a very tall inside chimney and has huge drafting, my baro runs 1/4-1/2 or more open when it gets really cold and stays that way a lot.
WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: CFT (covection fan threshold)

PostBy: mjwood0 On: Thu Oct 30, 2008 9:31 pm

I'd be very hesitant to remove the baro damper. It's there for a good reason as WNY has stated.

I know that for me, my baro is almost always 1/2 - 1/4 open even with the Power Venter rheostat turned all the way down. But if I didn't have the baro in there, I'd be burning a LOT more coal. It would burn hotter and all get sucked out the vent. Not good.

It sounds like you're getting stuff sorted. It took me about a month before I had things tuned up the first season. Last year (my second season burning coal), it only took a week. I just fired up today so I don't expect things to be perfect. But I've got tomorrow off and the weekend off so I can fuss with it to tune it in again for the year. Hopefully, by Monday, it will be running like a champ!
mjwood0
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: Econo

Re: CFT (covection fan threshold)

PostBy: AKHEARTH On: Fri Oct 31, 2008 7:29 am

Is there a way to tell if you are losing too much heat out the chimney? I do seem to be burning WAY to much coal.
AKHEARTH
 
Stoker Coal Boiler: EFM 520

Re: CFT (covection fan threshold)

PostBy: WNY On: Fri Oct 31, 2008 7:36 am

If you are not getting heat out of the stove
How much is WAY too much, on a full burn for 24 hours, you can easily run thru 30-50# or more.
WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon