Efficiency When Running A Small Flush Insert Without Fan

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velvetfoot

Minister of Fire
Dec 5, 2005
10,202
Sand Lake, NY
I think I'm going to try running the little Quad 2700i without a fan as an experiment.
I realize I won't be getting as much heat out of it and I'll have to watch the temps, but the question is:

Will I use more wood?

I've operated in this mode in a power failure, but I'm wondering if I could do so in milder temps without sacrificing wood use efficiency.
 
Start with your manual. Some inserts are not supposed to be run without the fan running. If the manual/manufacturer says that it is okay, your efficiency will depend on a number of variables.

For example:

-Is the fireplace/chimney internal or external? External ones can act as a heat sink and radiate stored heat outside.

-Is there an insulated block-off plate? Without a block-off plate and a sealed/insulated chimney cap, you will lose a lot of heat, especially if it is an external chimney.

-Is it within a masonry fireplace? Masonry chimneys will store and radiate the heat vs a zero-clearance faux-fireplace.
 
As soon as i turn off my blowers the house temp starts dropping. I suppose it also depends on the air sealing in your house, but my house isn't terrible.
 
I ask a similar question the other day, and that is can you run an insert without the fan to heat during a power outage,im thinking of installing a fireplace and then an insert partly for use during a power outage.But the question remains can it heat your house without the fan and do it without damaging the stove?
 
Looking at the manual the surround looks pretty easy to remove, check out pg 42. I would recommend being familiar with how to remove it in case you have another power failure, removing the surround will enable you to run the insert hotter and get more air movement with no blower.

I would also look into insulating your fireplace if you have an exterior fireplace, it helps keep that heat from escaping to the outside brickwork.

As to your question will you waste wood if you burn it with the surround on with no blower, you will get the IR heat from the front, you will have to burn it at a lower temp to make sure you do not over fire the stove which will make your wood last longer, so I would say no it is not a waste if it is your last resort.
 
you will get massively less heat out, mine outputs nearly nothing without the blower.

your stove will get way hotter if you dont run the blower, so its much easier to overheat the stove if you load and burn it like you usually do.

I dont know if it *willl* damage it, but it would be more prone to, and you wont be able to heat your house to any satisfactory level.... for either you, or maybe your pipes.

Get a cheap generator to run the fans.
 
I will guess that it will burn more wood. The blower takes heat out of the stove: without it the heat goes up the chimney, increasing draft and therefore burn rate.

The question of efficiency, as in- how much heat per pound of wood- is answered above. The blower is supposed to compensate somewhat for the lower area of the insert relative to a free standing stove. No blower, less heat radiating into the room, less efficiency.
 
I'll answer your question about using more wood. If you load your stove with the same load of wood (using blower, not using blower), which would result in using more wood.

Simple answer is you use more wood with the blower on. Reason - you are cooling the "stove" off by around 100 degrees running the blower which will require you to keep the air open a little more to keep it from coaling towards the end of the cycle.

With the blower off, you can use less air and the "stove" will remain hotter longer (* as long as you have a blockoff plate).

I run my insert with the blower off during the day. The blockoff keeps the heat on the inside of the firebox and heat pours out of the small gap (doesn't fit flush against fireplace face) I have around my insert. It heats the brick hearth as well as the cast which retains heat. I can do this as insert is in my family room/kitchen area where we spend most of our time. Overnight burns or real cold days I use the blower to move that heat out.
 
Thanks. I have tile up against the surround, so I'm not sure if it'll come off too easy - maybe.

I'm figuring it might use a little more wood but the heat coming out would be low and the fire would take constant watching.
Probably not worth the hassle, but it'd be nice if it was quiet.
 
Like said in the above post, the bottom line is with the blower off, the stove temps would stay higher longer, this means you can/need to decrease air intake, so wood would last longer.

But this does not make sense at all, why would you waist all this heat (heating all this brick mass)? If you are talking about power outages then another cheap option is to get a deep cycle marine battery (from COSTCO) and a 12v to 115V cheap converter, this should last a day or two maybe longer on low speed.

Oh, and efficiency would definitely decrease, not stove efficiency, but overall heat efficiency, especially if the stove is installed in an exterior wall.
 
velvetfoot said:
Thanks. I have tile up against the surround, so I'm not sure if it'll come off too easy - maybe.

I'm figuring it might use a little more wood but the heat coming out would be low and the fire would take constant watching.
Probably not worth the hassle, but it'd be nice if it was quiet.

Yes, I know, my 3100i fan was noisy as well, but I got used to it. Try to run it on low, see if that helps. You should still be able to get good heat this way.
 
I think whether or not it will burn safely depends on the stove and setup. In my setup, i cannot burn a full load without the blowers, it just gets to hot. The 6 day power outage we had at the end of october gave me a pretty good feel to how to run the stove without power. First off, the stove is probably 70% more efficient with the blowers. also, if you need to run without the blowers, take the surround off. If operating with the blowers, leave the surround on. I found this to be the reason. During the outage, i found i couldn't load the stove full because my stove overdrafts a bit. I ran a smaller load and took the surround off to let the heat escape. When i needed to get the house up to temp quicker in the morning, i ran the blowers off an inverter from my car. During the day when i was at work and werent running the blowers, the wife threw a couple logs every couple hours and it would stay pretty warm. We also kept upstairs doors shut and other things to keep the heat where we were staying. After we got the power back, i thought i would run the stove without the surround because of my experience during the outage. There was no difference in heat output as the blower is taking all the heat from the stove before it radiates anyway. What i was missing was the heat towards the end of the load. Without the surround, the air from the blowers was getting colder quicker at the end of the cycle. With the surround on, it traps more heat in the masonry, and that comes in handy when the fire dies down. I get heat for a longer amount of time. My block off is up near the damper, so a lot of heat gets trapped there. My next experiment is the add a lower heat shield angled to allow heat that would be trapped to roll out from the firebox. it would be curved to match the arch of the of opening of the firebox.

Hope this helps.
 
I disagree. I run my insert air all the way closed, blower on full. A hotter stove will draw more air through the same air inlet. If you do need to leave the air open a bit then you're compensating for the draft difference and probably burning at the same rate I'd think.

stejus said:
I'll answer your question about using more wood. If you load your stove with the same load of wood (using blower, not using blower), which would result in using more wood.

Simple answer is you use more wood with the blower on. Reason - you are cooling the "stove" off by around 100 degrees running the blower which will require you to keep the air open a little more to keep it from coaling towards the end of the cycle.

With the blower off, you can use less air and the "stove" will remain hotter longer (* as long as you have a blockoff plate).

I run my insert with the blower off during the day. The blockoff keeps the heat on the inside of the firebox and heat pours out of the small gap (doesn't fit flush against fireplace face) I have around my insert. It heats the brick hearth as well as the cast which retains heat. I can do this as insert is in my family room/kitchen area where we spend most of our time. Overnight burns or real cold days I use the blower to move that heat out.
 
If your insert comes STANDARD with a blower, I'd refer to the manual
as to operation with it off. If your insert has the blower listed as an
OPTION - like the Regency models do - that question is answered.
 
I tried the same experiment with my insert to see how low the outside temp had to be before I needed the blower and was surprised to see that the radiant heat did a good job well into the low forties, I also have a full masonary fire place which helps keep heat from escaping up the chase, you just have to try different methods till you find what suits your home.
 
You wont get nearly the same heat. My insert blower moves a ton of air and you can feel what feels like 250F air blowing on you on the couch 9ft away and blows papers on the coffe table in front of it. If i run no blower i get way less btus! I guess it goes up the chimney. Like another said i would get one of those tiny 2 stroke generators that are on sale at the big sale times or from harbor freight for $89-99. The can easily run your blower and another few fans, i think they are somethink like 700-800watts.
 
Because of the last outage,I picked up one of the HF generators till I figure what to do permanently( more expensive generator)
 
I put a Kill-O-Watt meter on my insert - 50 watts on low/ 100w high

My 200 watt inverter that I use for the laptop will run it on low no problem if I don't want to run my 800w HF generator at night.

I get almost no heat from my insert with no blower
 
On the silencing front:
I was thinking yesterday about how to quiet the blower noise.
The underside of the fan is open (not sitting on hearth - sitting in prefab), there are vents in the metal fan shroud, so I tried covering the bottom up with a folded newspaper (it's cold there).
That reduced the sound somewhat; the sound probably reflects off the hard hearth surface.
I might try putting some micore there, paint it black, not sure how to fasten, but what the hay. They use micore for sound attentuation, I believe, so it might be a good application.

I have a fantech 15watt radon fan in the basement that's always on, and has been for years; puts out a good flow.
I just haven't thought of a way to remotely (or otherwise) locate a similar fan and duct air to the opening.
Perhaps the squirrel fans are just generically noisier than enclosed fans and there could be a replacement of some sort that'd be quieter.
 
My quad 2700i is also on the noisy side (my research before purchase showed this to be the one common complaint). I would estimate I get a quarter of the heat out of it with the blower off. My plan is to temporarily remove the surround when the power is out. I need to make a heatshield for the mantle first, I worry about the extra heat going straight up under it. I imagine the published clearances assume you have the surround installed.
 
I checked tonight and it does look like I can take the surround off but I'll have to look into that a little more carefully so I don't mess up the adjacent tile.
The insert is inside a zero clearance fireplace, so I guess that'll behave differently than a masonry fireplace.

On the noise front, tonight I also cut a piece of micore to fit the underside of the blower shroud, which, as I said earlier, is hanging about 4" above the floor. It seems to have cut some of the sound transmission - not hugely, but noticable. I painted it black so it wouldn't stand out.

I have an IR thermometer from Harbor Freight which is handy to measure stuff like mantle temps.
 
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