Increasing Fireplace output

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sr73087

Member
Dec 20, 2016
72
SW CT
I haven't been burning heavily for more than the last two winters, but noticed I can have a roaring fire going, burning through tons of wood (all free off my property) but still have minimal output. My home is a 2 story, fairly closed floor plan colonial. Burning for 12-14 hours straight some days, I am only able to raise the temperature in the catty-corner room where the thermostat is by a degree or 2 at most. Without closing the doors in the room where the fireplace is, I feel minimal difference from the other rooms. My question is, other than installing an insert (which may happen), what are some other options to increase the output of this fireplace and slow down how much wood I am burning? I have seen firebacks but those cost almost as much as a used stove in some cases.
 
Do you have a masonry fireplace or a zero clearance unit? that is one of the deciding factors on being able to install a insert. Generally speaking though, fireplaces actually suck heat out of the house, they do provide minimum radiant heat, and some have a heatilator built into them, but again they are not very efficient heaters.
My neighbor was a mason during his working years and he built a rumford type of fireplace, shallow back wall on an inverted angle, the fireplace does do a descent job, but a regular fireplace tends to just sent the heat up the chimney, make up air then enters the house through insulation cracks and they place gets cooler.
If you have a zero clearance fireplace, you can replace it with a new epa approved heater, these fireplaces do a great job with heating homes, although many are blower dependent so you will new electricity for it to run properly.
A wood insert is made to go into a masonry fireplace (most inserts are only made for masonry fireplace, few are tested and approved for zero clearance retro fit jobs)
with an insert you will need a liner, smooth wall stainless that is insulated is the best, usually depending on the existing chimney size a 6" insulated liner will fit with minimum cutting (like a damper in the fireplace) some people with narrower chimney's will knock out the clay liner to make the liner fit, others that a internal chimney that is code compliant (clearances) will just install the liner with out the insulation.
Many people also install an insulated block off plate, this helps with keeping the heat that the insert produces from going up the chimney between the liner and masonry or being absorbed by the masonry (think giant heat sink)
 
Your fireplace is sucking somewhere in the neighborhood of 200 cubic feet of warm air out of your house every minute. You aren’t going to be able to heat your home unless you install an insert or a freestanding woodstove. I personally enjoy an open fireplace, but not once heating season is in full swing. Maybe you could put a freestanding stove in another location?
 
I remember back when I was a young kid. The power would go out often and for extended periods. My parents would build roaring fires in the masonry fireplace to keep warm. The only way it was comfortable in the livingroom was when they would hang sheets over the archways to the rest of the house. Then it would keep us warm through radiant heat. Fireplaces do not heat a house as a whole. Their net efficiency is less than zero. Simply put an open fireplace costs money to burn. Your furnace will run more not less. No wonder the big old farm houses had a fireplace in every room and every bedroom as well. I know of a few of those old houses that have 6 or 8 fireplaces, 2 to a chimney. Nothing more than standing beside a campfire.
 
The only significant way to increase a fireplace's performance is to put an insert or stove in it. It's truly night and day difference. From a heating perspective, an insert will provide 7-10 times more heat to the home (seriously). From a wood supply perspective, you'll significantly cut down the amount of work you put in to collecting, cutting, splitting, stacking, and reloading. Just think what you could do if you used just half the wood you have in the past - or doubled the amount of time you heat with the same amount of wood you've used so far.
 
Ben Franklin I am not, but I actually have an idea. I am just going to tag @begreen now so he can explain the error of my thinking before you go on a snipe hunt.

Talk to your local hot rodders and find an exhaust shop. Go to TJMaxx and by a spare fireplace grate. Measure you fireplace up real careful.

Take your measurements and spare grate to the exhaust shop. Ask them to bend up some 2" SS exhaust pipe in a C shape, and use some baling wire to attach the manifold to the grate - that will fit inside your fireplace.

You want enough air space in the floor of the grate to still feed the fire good. If you get it set up right, those 2" pipes, maybe three or four of them, will suck in some of the air that was going to feed the fire. The air in the tubes will heat up and rise. If you got you intakes and outlets set up right relative to the mouth of your fireplace you might be able to raise your 10% efficient fireplace up to 15 or maybe even 20 % efficiency.with the hot air coming out of the top of the pipes coming into your fireplace room instead of going up the chimney.

Be advised exhaust pipe ships with lube on it so the tech can put the pipe straight into the bender. Once your thing is built you will want to run it in your outdoor fire pit, hard, to burn the lube off it before you bring it indoors.

FWIW a genuine antique Franklin stove hooked up to a fireplace will run ~30% efficient and set you back some $100k as a historic antique. My modern freestander is rated near 90% efficient and was under $5k. In 1990 dollars you can probably put a Meineke/ Midas hack on your fireplace grate for maybe 100 bucks or so.
 
We need more details on your fireplace. Masonry? Steel?

Do you have an outside air intake? You will never get anywhere without an outside air intake.
 
That heat generator tube contraption is as old as the hills. They had them when I was a wee lad. A masonry fireplace is more like negative 30% efficient. The tube thingy will bring it up to negative 10%.
 
The problem with a fireplace is unless you are burning 24/7 you need to leave the damper open when the fire is going out. The flue is still going to be sucking air up it until its cool enough to close the damper (most folks leave the damper open as its usually a PITA to close it and and a PITA if they light a fire with it closed). With the damper open overnight its going to suck any heat you may have put in the house up and out the chimney.

We tried to supplement our heat with a fireplace in our basement for a couple of years, if we kept the door to the main floor closed when we stopped burning we cut back on the heat being sucked out the main floor. After a couple of years my dad made up a closely fitting plug that fit in the front of the fireplace to seal off the opening. It was long ago enough that the plug was faced with asbestos cement board. I have seen glass doors that purport to do the same thing but frequently they are not very tight at the seams. After years of throwing wood up the stack, we put in a woodstove conversion that consisted of a steel plate that covered the front of the fireplace with the back of woodstove bolted up directly to it. There was no direct connection to the flue, the gases just dumped in the firebox and found its way up the flue. Not ideal and a pain to get lit, but once lit it made a world of difference. Our wood usage was cut in half and we could leave the doors open to the main floor of the house.
 
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An insert or perhaps a rear-vented stove connected to a liner going up through the fireplace flue is going to provide the most heat with the least heat loss from the room. A fireplace may provide some short term radiant heat but it can not compete in this regard with a good stove or insert.
 
In an attempt to make his fireplace into a heater, my brother put glass doors on his fireplace. He could control the burn better. But it would get to hot and break the glass. After a few glass replacements, it's never been used again.
 
In an attempt to make his fireplace into a heater, my brother put glass doors on his fireplace. He could control the burn better. But it would get to hot and break the glass. After a few glass replacements, it's never been used again.
If you use pyroceram doors, they won't break but at what it cost might as well get a stove.