blower ideas?

Instead of modifying blower just use a good fan to push cool air back to the insert. This way the temps will stay higher. I personally don't like to move too much air over a stove. On an insert you want the air to be slow (low velocity). Just my opinion.

realstihl said:

Instead of modifying blower just use a good fan to push cool air back to the insert. This way the temps will stay higher. I personally don't like to move too much air over a stove. On an insert you want the air to be slow (low velocity). Just my opinion.

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My old bk fan works, but doesn't blow out 8 feet either. It's pretty loud on high, and have to crank up the little speakers on the flat screen to almost max. I've wondered for quite a few years if it was possible to modify something like dryer exhaust tubing hose to the inlet on the bottom of the stove where the two little computer like fans are. I was thinking of hooking it up to a small squirrel fan I have for drying out flooring after a flood. Not cheap, but it's pretty quiet for the amount of air it pushes. Maybe paint the hose and blower black, and set it next to the stove with a box over it so it looks like it may belong there. Just a wild idea I've had for years, but never tried it.

bump. for new answers.

I researched and added a blower to my old insert (no longer installed). Found a dayton that was approximately the same size outlet as the inlet hole and with a little high temp silicone and a few holes drilled into the blower, voila!

But, in getting a much larger blower, I would watch my stove temps plummet (even with the air wide open). It worked good for getting a cold house up to temp, but not so much for just steady burning. Plus a much bigger blower was even louder than the blower that came with it.

All in all, a bigger blower will rob the stove of enough heat that it no longer functions as efficiently.

The blower is 130CFM for a reason.

aphares said:

bump. for new answers.

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Please be aware that running a blower will not get you more heat; instead it will transfer the heat from the insert to the room faster. The amount of heat you get from an insert is the heat stored in the wood minus the heat going up the flue (minus the usually negligible amount of heat retained in the coals after the burn). A blower may change that equation only to the effect as it could reduce the stovetemp which may have an impact on the insert's efficiency. It will probably be hard to quantify that but my guess is that a blower can help during the early parts of the burn (when the insert is up to temp) to lower a bit the peak temp which may reduce the risk of unburnt particles going up the flue. However, after some time it may become counterproductive when it cools down the insert so much that the combustion temp is not high enough anymore but you are not quite yet in the coaling stage. This guess of mine assumes there is an optimal temp range a secondary burn stoves likes to operate in and a blower can help to keep it below the upper threshold but should not push it below the lower one.

In any case, a blower will help if you want to heat up a room fast after starting a fire. It will also help if you run the risk of overfiring the insert. Now, the other question is how efficient is your installation? Do you have a block-off plate installed? Is the fireplace at an interior or exterior wall? At an interior wall, all heat captured in the fireplace will heat up the masonry which will release it to the house over time. In an exterior fireplace, some of that heat will go to the outside. Putting Roxul behind the insert and maybe its sides may help retaining that heat. Running the blower may also help but better insulation would be the more efficient solution, IMHO. Here is a link: https://www.hearth.com/talk/threads/finally-got-around-to-insulating-my-fireplace.75755/

To summarize: If you suspect your insert is not heating well enough, the blower is not the place to start looking for improvements. Check your burning practices and the dryness of the wood to minimize the heat that goes up the chimney. Then check your installation whether you retain the heat generated by the insert within your house (block-off plate, insulating a fireplace at an exterior wall). If that does not fix it, upgrades to the overall insulation of your home and/or a bigger insert may be required.

Grisu,

I respectfully disagree. Airflow (or fluid) over a heat exchanger will increase efficiency of heat exchange.

madison said:

Grisu,

I respectfully disagree. Airflow (or fluid) over a heat exchanger will increase efficiency of heat exchange.

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But it does not get more energy out of a certain amount of wood than what is in there to begin with. (First law of thermodynamics) As I said, the blower may affect your burning process and there is a potential that it will help to increase the efficiency slightly when it reduces the peak temp so that less unburnt particles/gases go up the flue at very high stove temps. (Essentially overwhelming the secondary burn or cat.) Other than that I don't see how with a blower you can get more heat out of a stove other than maybe reducing the burn time so you have the impression that you get more out per hour. Does not mean you get more out of it overall from a fixed amount of wood.

Grisu said:

But it does not get more energy out of a certain amount of wood than what is in there to begin with.

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Totally with you on this one Grisu (especially since I was pigheaded and tried a larger blower on my insert)........

At some point you put enough heat from that insert into the room that the insert temp and stack temp are lowered to a point that the stove is not burning well any more. It makes a mess of the whole process. You must learn to let your appliance "cruise"........get it to an appropriate operating temperature and keep it there.

Grisu said:

But it does not get more energy out of a certain amount of wood than what is in there to begin with. (First law of thermodynamics) As I said, the blower may affect your burning process and there is a potential that it will help to increase the efficiency slightly when it reduces the peak temp so that less unburnt particles/gases go up the flue at very high stove temps. (Essentially overwhelming the secondary burn or cat.) Other than that I don't see how with a blower you can get more heat out of a stove other than maybe reducing the burn time so you have the impression that you get more out per hour. Does not mean you get more out of it overall from a fixed amount of wood.

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I gotta respectfully disagree also.

Heat will transfer faster to a colder object ,that is fact.

Check my sig.

smokedragon said:

Totally with you on this one Grisu (especially since I was pigheaded and tried a larger blower on my insert)........

At some point you put enough heat from that insert into the room that the insert temp and stack temp are lowered to a point that the stove is not burning well any more. It makes a mess of the whole process. You must learn to let your appliance "cruise"........get it to an appropriate operating temperature and keep it there.

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There is no fan big enough to cool the temps in the stove by much. There is fire in there! lol

But all that said cooling the stack is not good. I never have liked a insert. They can look nice though.

HotCoals said:

I gotta respectfully disagree also.

Heat will transfer faster to a colder object ,that is fact.

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Faster, yes. That is exactly what I said, too:

Grisu said:

Please be aware that running a blower will not get you more heat; instead it will transfer the heat from the insert to the room faster.

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Nevertheless, I am a firm believer in the 1st law of thermodynamics:

energy transferred as heat to room = energy contained in wood (1) - energy lost through flue (2) - energy retained in remaining matter/coals (3)

A blower has no impact on one, so it must reduce either two or three in order to give you more heat from of a given quantity of wood. For (3), the far more likely scenario is that a blower will increase the amount of coals left when it cools the stove too much and your coals don't burn up fully. Maybe a blower has an impact on (2) and I gave a possible scenario in my above post. Still, if it would have such a serious positive impact on efficiency, the EPA would require the use of a blower with all stoves.

HotCoals said:

There is no fan big enough to cool the temps in the stove by much.

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It sounds totally stupid, and I used to would agree with you, but it happened to my insert.......I had a monster Dayton blower that would lower the stove top temp from 600 to 350 in just over an hour and a half. Now it was an old smokedragon, so I can't speak for the effect on a newer and more well designed stove.........

Just FYI: The original blower on my insert was around 80 CFM. The Dayton I installed was 580 CFM. If you got the stove rolling and then threw that blower on, it would really heat the house up quick, but you just couldn't run it like that for long or the stove actually stopped burning well.........like putting ice around the stove.

Which is why when it comes to blowers, stick to what the manufacturer mated to it, or a little bigger. I went way overkill

Pulled off the big Dayton and went back to the factory blower.

Suppose you get into your automobile on a very cold day, and you wish to heat the interior of the car. Do you turn the interior fan on once the engine is warm, or leave it off?

Heat exchange is different than the total BTU's available. Obviously the total energy available in a load of wood is not affected by the blower.

Heat exchange efficiency is described in the 2nd Law of Thermodynamics.

madison said:

Suppose you get into your automobile on a very cold day, and you wish to heat the interior of the car. Do you turn the interior fan on once the engine is warm, or leave it off?

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If the engine would be on the passenger seat, it would make only a small difference. Mainly make me warm a little bit faster. The total heat delivered by the engine for a given amount of gas will be the same. A stove is within a shell, not outside like a car engine. If you would not turn on the car blower, the engine will heat the outside air, not the passenger cabin.

It is really not rocket science. Any energy not going up the flue will end up in your home. It does not disappear. A blower will make you feel warmer faster but the total heat delivered over the burn will be the same as long as efficiency is not affected.

I think what Grisu is getting at is there are two types of efficiency. Combustion efficiency and heat transfer efficiency. Combustion eff. is the amount of energy that is produced from the wood you burn. Heat transfer eff. is the amount that energy(heat) that is transfered to the room. Your heat transfer eff can be 90% but if your combustion eff is only 40% then the fan can only transfer 90% of that 40%. Thus if you increase your combustion eff higher(say 70%) you will feel more heat. 90% of 70% produced.

Grisu said:

If you would not turn on the car blower, the engine will heat the outside air, not the passenger cabin.

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The analogy I was trying to make was for heating the interior of the car, not the exterior engine compartment. So you turn the car's heater blower on to REMOVE engine heat (via the engines cooling system) and warm the interior of the car.

Regarding heat lost up the flue, if you remove the heat from the stove exterior more efficiently - i.e. with a blower - less heat would be lost to the chimney.

Nonetheless, I do agree with some of your thoughts - just not all of them... No big deal. I'll still continue to use the blower.

Fundamentals of Heat Exchange: http://www.google.com/url?sa=t&rct=...t8iJuSyd-TYmHgUv43TT3Pg&bvm=bv.65177938,d.cWc

madison said:

Regarding heat lost up the flue, if you remove the heat from the stove exterior more efficiently - i.e. with a blower - less heat would be lost to the chimney.


Fundamentals of Heat Exchange: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCYQFjAA&url=http://www.aip.org/tip/INPHFA/vol-2/iss-4/p18.pdf&ei=qfZXU8KMNYLNsQSf0oHADQ&usg=AFQjCNEZjE_t8iJuSyd-TYmHgUv43TT3Pg&bvm=bv.65177938,d.cWc

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Not really. "heat lost up the flue" may be in the form of unignited gases from incomplete combustion. If you are not getting a high percentage of the available BTU in the wood out of the combustion process you can not regain that regardless of the size blower you use. So first you would have to make sure that you are obtaining the maxium efficiency off the burn as possible. Then you can decide if that blower is transfering an exceptable percentage of that heat to the room. A higher CFM blower will lower the firebox temp and that will lower the efficiency of the combustion (produce lower BTU output). You could lose some heat on the secondary burn. Also risk higher creosote production.

@ madison
BTW I'm originally from Orange county too.

This doesnt pertain to the OP's stove but on a thermostatically controlled stove would the blower inducing lower box temps prompt the stat to increase combustion, hence making more heat and a faster burn. More heat into the house in a shorter time period?

When you say thermostatically controled stove, I think of a bi-metalic thermostat attached to a damper (maybe on the feed door).
IMO and others may have a different POV (maybe a better one too) That would open the damper allowing more combustion air into the combustion chamber. Now complete combustion requires Temp., turbulance(air mixing with the gases) and time (amount of time the gases need at a certain temp, between roughly 525 degrees and 1100 degrees, to fully ignite) so adding air to fix a temp issue may not help. It may (again IMHO) increase your draft and reduce the time the gases are exposed to the air and temp. If you were to close down a hand damper in the stove pipe to slow the draft it may counter that effect. This is an off the hip answer. But trying to make up lower temps with higher air flow i don't think will help combustion and may hurt it more.

I'd be interested in others thoughts on that though

I'm talking like a BK cat stove with the bimetallic stat controlling the incoming combustion air, there are others too, first that comes to mind is the US Wonderluxe......

I use a ceiling fan blowing down on high speed to "push" the warm air into the other parts of the house

Now with Cat stoves it is different because the secondary burn occurrs at a lower temp . Higher temps can damage the cat. On the Wonderluxe or other Ashley circulators they are designed to burn at a 35:1 air to fuel ratio (thus the EPA exempt status) anyway. But that was the exact Bi-metalic type thermostat I was thinking.
On the OP I think the question was answered well by smokedragon and BG from the begining. The blower on the unit is designed that way for a reason and shouldn't be modified, besides the fact you could risk your HO insurance denying a claim should something happen. If you feel the stove has a lack of heat problem you can look to other things like Grisu said

Grisu said:

To summarize: If you suspect your insert is not heating well enough, the blower is not the place to start looking for improvements. Check your burning practices and the dryness of the wood to minimize the heat that goes up the chimney. Then check your installation whether you retain the heat generated by the insert within your house (block-off plate, insulating a fireplace at an exterior wall). If that does not fix it, upgrades to the overall insulation of your home and/or a bigger insert may be required.

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