recessed can ligh to blame? ----Title was "how a leaking block off plate afftect performance?"

[ba_jie]

Hi,
I know a block off plate will improve the heat usage dramatically from the posts here.
My Jotul 450 setup has a block off plate that i made myself. But for some reason, i still have trouble to heat my family room.
The family room is about 20'*15'. It has high ceiling and open to the Kitchen and the rest of the house. The house is about 3200 sqf(2 level).
With help of ceiling fan, i can barely get the room temp above 55 degree. This is after i run the stove for about 6 hours. I know i should have get a
thermostat, but... that's not the point. My question is, if the block off plate is not sealed completly, will that void the whole effort of having one?

I made the block off plate myself, i am certain it's not made fit 100% around the liner. I kinda puzzled mutilple metal pieces to fit around the liner. I then drilled and screwed them together. I applied furnance cement to the gaps i could detect. However, i still can't say it's completely sealed.
So could heat escape from those some unsealed gaps? That's my concern after so many failed trials to heat the room.

I can feel the heat 2~3 feet away when the fan is turned on at "Low" level. If i put the fan at High level, the fan will switch on/off constantly. Does that mean the stove is not hot enough? As for the surface temp of the stove, i can briefly touch my finger on the stove door or neck.

So is it my stove? my room size? or block off plate? Thanks.

 

[stejus]

I don't think a leaky block off plate will steal that much heat. I have an HI300 installed with a full flue liner sealed at the top. I am getting heat throughout my house with no problem. The 450 is a serious stove but your room layout my be too open and too big. Load the stove with dry wood, run it wide open until all logs are flaming high, back it down and stove temp should rise to a safe burn temp (300-600 degrees). This should give use the most heat. When the stove is running at it peak, you can bairly stand next to it, let alone breifly touch the door or neck. Good luck.

 

[Jags]

As said above, a few tiny leaks in your blockoff plate is probably not going to gain you any big time heat. Consider it more comparable to a leaky window or door.

 

[Hogwildz]

If the fan is turning on & off repetitively your not getting the stove hot enough.
Are you getting a good secondary burn? Glass always going black? Have you checked the stack & cap to make sure its not getting heavy build up.
All these will indicate if burning hot enough or not, or possibly wood thats not quite ready.

 

[ba_jie]

Thank you all for your replies. I am relieved that i probably don't need to redo my block off plate.
I occasionlly observed secondary burn. If my assumption that flame around the top tube are what so called secondary burn.
My glass does get black very quick.

So i guess this is the wood problem. My firewood may still not dry enough.

If the fan is turning on & off repetitively your not getting the stove hot enough.
Are you getting a good secondary burn? Glass always going black? Have you checked the stack & cap to make sure its not getting heavy build up.
All these will indicate if burning hot enough or not, or possibly wood thats not quite ready.

 

[oconnor]

Do you have a thermometer on the stove? If so, you should be able to get it quite hot (I can easily hit 750*F on the stovetop) with dry wood. When I have damp wood (30% moisture reading), my stove tops out around 350-400.

Is that what you are experiencing? I found this stove really picky about wanting dry wood.

Also, the snapstat on my Kennebec fires up about 30 mins after I light it, and will run all night long, even after the fire is out. If yours is cycling, you may not be getting much heat from the wood at all. If you don't have one, pick up a thermometer and get an objective reading of stove temp. At least then you can compare it to others with the same stove.

Good luck

 

[ba_jie]

Today when i looked at the high ceiling of the family room. It suddenly occured to me that those recessed lights might be the reason why i can't get the room temp up.
I have 6 recessed lights on the ceiling. Does anyone have idea how much heat loss will be caused by those lights?

 

[mcollect]

The lights, depending on type require no isolation within 3 to 6 inches of the unit and none above the unit (lightolier}. I found this out last weekend when I installed a fan in one of them. But I don't think that is your problem, I am betting on not dry enough wood. This is my first season heating with a 550 and I only ordered my "dry wood in June. Try to split your splits down to 3" size and bring them inside for a week before burning, it works for me!

 

[oconnor]

I am thinking the lights aren't the problem.

Did you get a thermometer? if so, what temps are you getting? If the stove is hot (600-700) then we at least know the heat is being produced.

here is my fire lighting thread - these stoves are picky eaters, and hate wet wood worse than brussel sprouts - https://www.hearth.com/talk/threads/31393/

Give it a try, and report back, hopefully with some temps so we can help you a bit more.

 

[gpcollen1]

If the fan is turning on & off repetitively your not getting the stove hot enough.
Are you getting a good secondary burn? Glass always going black? Have you checked the stack & cap to make sure its not getting heavy build up.
All these will indicate if burning hot enough or not, or possibly wood thats not quite ready.

It could also very well be the location of the snap disk if there is one - it needs to be located properly - as in touching the stove and not in the path of airflow.

 

[wolfkiller]

A word about can lights. Can lights look and light nice but can ruin a house if not installed properly in cold climate. Fist off only buy sealed direct contact cans. Then seal them even better with vapor barrior tape. Other wise you will have multiple 6" holes in your vapor barrior. Not only does this cause a lot of air loss is will cause the moisture driven vapor to your attic. I have seen 100+ gal of water + a lot of destroyed sheetrock and insulation from the ice in a attic melting in the spring.

 

[oconnor]

If the fan is turning on & off repetitively your not getting the stove hot enough.
Are you getting a good secondary burn? Glass always going black? Have you checked the stack & cap to make sure its not getting heavy build up.
All these will indicate if burning hot enough or not, or possibly wood thats not quite ready.

It could also very well be the location of the snap disk if there is one - it needs to be located properly - as in touching the stove and not in the path of airflow.

The "Snapstat" on the C450 actually rests on an airchannel, not the stove itself - that is how the manual displays the install. It is set actually quite low, and runs on mine for 4-5 hours after a fire is gone to coals.

 

[myzamboni]

Today when i looked at the high ceiling of the family room. It suddenly occured to me that those recessed lights might be the reason why i can't get the room temp up.
I have 6 recessed lights on the ceiling. Does anyone have idea how much heat loss will be caused by those lights?

I have 20 can lights in the main area my stove heats. I've been in the attic with an IR thermometer gun and I am not losing heat out the cans.

You are not burning hot enough and your wood is not seasoned enough.

 

[JerseyWreckDiver]

Today when i looked at the high ceiling of the family room. It suddenly occured to me that those recessed lights might be the reason why i can't get the room temp up.
I have 6 recessed lights on the ceiling. Does anyone have idea how much heat loss will be caused by those lights?

Absolutely could be the problem. If they are the older, Non IC rated lights that have holes in the casing (you'll see light coming through into the attic) these lights when on are known to move approx. 15 CFM each. If they are this type, do not under any circumstances cover them with insulation, it wouldn't help anyway except your room temps will definitely go up while your house is burning down...

If they are the newer IC rated lights that have a sealed can then that is not your problem. You could always change over to the newest lights that are now quite air tight even compared to the older IC rated.

Otherwise how is your insulation level in your attic/walls? For that matter check out your attic while the stove is cranking, it should be almost as cold up there as it is outside, too warm and you are leaking heat into the attic, have really bad ventilation or both.

 

[JerseyWreckDiver]

Today when i looked at the high ceiling of the family room. It suddenly occured to me that those recessed lights might be the reason why i can't get the room temp up.
I have 6 recessed lights on the ceiling. Does anyone have idea how much heat loss will be caused by those lights?

I have 20 can lights in the main area my stove heats. I've been in the attic with an IR thermometer gun and I am not losing heat out the cans.

You are not burning hot enough and your wood is not seasoned enough.

Yours may be a sealed fixture, his may not be. Is your house 3000 sf? Big house to try to heat with one stove. Are your outdoor temps same as his? Lot of assumption happening here...

Jie what region of the world are you in??? Alaska, Florida? Honduras? What kind of outdoor temps are you seeing?

 

[myzamboni]

Today when i looked at the high ceiling of the family room. It suddenly occured to me that those recessed lights might be the reason why i can't get the room temp up.
I have 6 recessed lights on the ceiling. Does anyone have idea how much heat loss will be caused by those lights?

I have 20 can lights in the main area my stove heats. I've been in the attic with an IR thermometer gun and I am not losing heat out the cans.

You are not burning hot enough and your wood is not seasoned enough.

Yours may be a sealed fixture, his may not be. Is your house 3000 sf? Big house to try to heat with one stove. Are your outdoor temps same as his? Lot of assumption happening here...

Jie what region of the world are you in??? Alaska, Florida? Honduras? What kind of outdoor temps are you seeing?

His stove glass gets black really fast. Classic sign of wood not seasoned enough and/or not burning hot enough. These do not sound like assumptions.

 

[ba_jie]

I am in Massachusetts. The outside temp is around 30F these days.
I should admit my wood is not dry enough because i can hear some sizzling sound when they are initially put in. But after like 10 min, the sizzling will be gone. Dry wood may help heating stove quick.
But, if i can not bring the room temp above 55 after burning for continuous 6 hours regardless the wood is dry or not, can i assume the hot air produced during the 6 hours have escaped?

I am not sure if my recessed light are ic rated or not. I do see lights in the attic. so it's likely they are non IC rated. Thank you all for help me trouble shooting the problem. I already placed an order for an IR thermostat. i will keep you updated about my discovery.

Today when i looked at the high ceiling of the family room. It suddenly occured to me that those recessed lights might be the reason why i can't get the room temp up.
I have 6 recessed lights on the ceiling. Does anyone have idea how much heat loss will be caused by those lights?

I have 20 can lights in the main area my stove heats. I've been in the attic with an IR thermometer gun and I am not losing heat out the cans.

You are not burning hot enough and your wood is not seasoned enough.

Yours may be a sealed fixture, his may not be. Is your house 3000 sf? Big house to try to heat with one stove. Are your outdoor temps same as his? Lot of assumption happening here...

Jie what region of the world are you in??? Alaska, Florida? Honduras? What kind of outdoor temps are you seeing?

 

[ba_jie]

This is first time i heard this technique. what do you mean by "block off the secondary air intake"?
You mean sealing the back air intake opening?

Thank you all for your replies. I am relieved that i probably don't need to redo my block off plate.
I occasionlly observed secondary burn. If my assumption that flame around the top tube are what so called secondary burn.
My glass does get black very quick.

So i guess this is the wood problem. My firewood may still not dry enough.

If the fan is turning on & off repetitively your not getting the stove hot enough.
Are you getting a good secondary burn? Glass always going black? Have you checked the stack & cap to make sure its not getting heavy build up.
All these will indicate if burning hot enough or not, or possibly wood thats not quite ready.

i'd try block off the secondary air intake for wet wood.

 

[oconnor]

....But, if i can not bring the room temp above 55 after burning for continuous 6 hours regardless the wood is dry or not, can i assume the hot air produced during the 6 hours have escaped?..

Your question about the heat escaping is a truism - if the temp is back where it started, then the heat escaped - the real question you need to ask is how much heat did you produce?

The only way we can tell how much heat you produce is a temp reading, but we don't have one yet. After that, we have the cycling snapstat, and black glass. Cycling snap stat is either bad snapstat, or cool temps. Black glass is cool temps.

Cool temps are wet wood, poor draft etc etc - poor combustion.

Heat transfer to the room increases with stove temp - Newton's law of cooling, states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings, or environment. That means that a hotter stove gives you more heat over a given period of time. The increase in the rate of radiation is not linear - it is calculated to the 4th power of the temperature of the body in Kelvin - so a 400 F (479 K) stove surface delivers 65% of the output that a stove at 500 F(533K) puts out - so getting the stove hot is important. Or said differently, a 600*K stove puts out 16 times more heat than a 300*K stove.

So if you aren't getting the stove hot, you will not get heat. Another truism.

Sorry for the science lesson, but before I looked it up, I didn't realize just how much doubling the temp increased the heat output.

 

[ba_jie]

Wow, amazing stuff.
I guess i forgot all i learned in high school physics class.
I will test the stove this weekend with wood from grocery store.

....But, if i can not bring the room temp above 55 after burning for continuous 6 hours regardless the wood is dry or not, can i assume the hot air produced during the 6 hours have escaped?..

Your question about the heat escaping is a truism - if the temp is back where it started, then the heat escaped - the real question you need to ask is how much heat did you produce?

The only way we can tell how much heat you produce is a temp reading, but we don't have one yet. After that, we have the cycling snapstat, and black glass. Cycling snap stat is either bad snapstat, or cool temps. Black glass is cool temps.

Cool temps are wet wood, poor draft etc etc - poor combustion.

Heat transfer to the room increases with stove temp - Newton's law of cooling, states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings, or environment. That means that a hotter stove gives you more heat over a given period of time. The increase in the rate of radiation is not linear - it is calculated to the 4th power of the temperature of the body in Kelvin - so a 400 F (479 K) stove surface delivers 65% of the output that a stove at 500 F(533K) puts out - so getting the stove hot is important. Or said differently, a 600*K stove puts out 16 times more heat than a 300*K stove.

So if you aren't getting the stove hot, you will not get heat. Another truism.

Sorry for the science lesson, but before I looked it up, I didn't realize just how much doubling the temp increased the heat output.

 

[Theo]

... Heat transfer to the room increases with stove temp ... The increase in the rate of radiation is not linear - it is calculated to the 4th power of the temperature of the body in Kelvin - so a 400 F (479 K) stove surface delivers 65% of the output that a stove at 500 F(533K) puts out - so getting the stove hot is important. Or said differently, a 600*K stove puts out 16 times more heat than a 300*K stove.

If you'll forgive me... a key word there is "radiation." Convective transport is a major mechanism for wood stoves, and - e.g. for inserts - sometimes the dominant one. (Likewise for so-called "radiators"; most home heating systems run at a temperature where convection dominates.) Heat extraction is more efficient at higher temperatures, but not usually so dramatically as a fourth-power dependence. Improving surface air exchange over natural convection, as with a fan, is probably something more people should consider.

-Theo
(not a science teacher; just a scientist)

 

[fossil]

The terminology, in common use, has taken some unfortunate turns. "Radiators" in vehicles should more properly be named "convectors", as they're really only effective when air is passing through them because of the motion of the vehicle. In the case of a woodstove, there is a considerable radiative component to the heat transferred to the surrounding space, as evidenced by the temperatures the fur on my cats reach after laying on the floor in front of the stove for a time. Of course, at the same time, there's a natural convective component from the front of an insert and all around a freestander. I don't know whether or not the radiative or the convective component is dominant...I imagine it depends on the appliance and the installation. I think that to take maximum advantage of the heat released by burning the fuel, an insert cries out for a blower to provide forced convection around the appliance and into the space. I've found that in some installations a blower on a freestanding stove increases its effectiveness tremendously, especially in combination with other things like ceiling fans which further destratify and mix/move the air. I'm neither a scientist nor a teacher, just an old retired engineer who learned all that Kelvin stuff, passed the physics course, then promptly forgot it all. But I still know hot when I feel it. Rick