Heating comparison: wood stove vs insert

That’s what I wonder about too but I’ll be able to ask that question when I get it installed and likely see the whole thing. Here’s a picture of the blower diagram for parts.

 

Hmm, so 2 smaller blowers, vs one larger one like mine, and like most have.

I'm sure there's other smaller blowers on the sure I linked to. Find out where the blowers go, it's literally a " if it fits in there it will work" thing.

 

Probably something like this.
Fireplace Blower - 150 cfm

 

I’m fine with jerry rigging if it’s internal, at least it can be doable. More than anything I’m worried about a shorting out due to incorrect wiring or components melting due to heat but I’m guessing that this encapsulated area is a good buffer area. Best I wait to see how the face comes on and off and look at it altogether.

 

It's not really Jerry rigging. Not the kits like I linked. But I get your point. These kits are really just like the factory ones. I tried looking online for pictures of you stove's fan/ setup. But there's nothing I see. Looks like lopi put a nice wire grommet to run the wiring through.

 

The reason is because the heat from the glass and door is radiant heat. That's how a freestanding stove heats; by radiating in all directions.
An Insert uses convection to move heat. That is the heat transmitted to the air in the chamber around the firebox.
Moving that convected heat into the room is much more efficient with a blower than gravity.

It would be perfect if the mass of the masonry radiated all the heat into the home. However, it radiates rearward and upward into the masonry mass, radiating outside in an exterior chimney, as well as up into the mass of masonry and out the roof. You want to remove all the heat you can using convection. Hot air rises, but heat radiates in all directions. The blower will move it forward.

 

The CFM of the blower is very important. The higher the CFM, the slower the blower can be ran making it much quieter. Always connect with variable speed switch.
Woodmans's has 3 1/2 high X 17 1/2 long with cooling fan on motor up to 215 CFM. They are mounted below the firebox at the coolest area.
Outside mounted are the best, but visible. It needs to be strong enough to move air under the firebox, up the back, and forward, over the firebox moving air into the room. Too much cooling of the firebox is detrimental to a clean fire, resulting in not enough draft in the chimney for correct operation.
I can only give you minimum CFM for Fisher brand, that is much higher than 150.
They also were designed to protrude from the hearth by 1/2 the depth for using radiation of the front half without electric, and provide cook top for humidifying the air. Convected heat is very dry.

If there is any combustible mantel, a diverter over the insert upper outlet is normally required to prevent heat rising up the fireplace face.

 

I wondered about the diverter. A tv is mounted above the mantle as well. I don’t know what these diverters would be looking like but nothing on the Lopi site except the heating line.

 

FatBoy85 I installed a small cast iron stove in a masonry fireplace with no block off plate, only some insulation last year. When I did my cleaning and inspection of the chimney liner earlier this season I noticed that my top plate seal has blown out on one side. I’m assuming this is from the extreme heat that builds up in the chimney because of no block off plate.

 

I’d like to see what that looked like if possible...

 

Diverter / Deflector can be made of any flat plate, sheet metal, coil stock...... to divert rising heat as shown below;

This was supplied with Fisher Inserts.

Installed as shown.

The deflector sits on top of the outer shell and is bolted in place with machine screws you can see in the outlet slot.

The Insert shown has external blower that was made in many varieties and blows into a slot under firebox, up the back, over the firebox exiting through slot below deflector. The most heat was extracted from the exhaust vent area where the Flue Vent was exposed between firebox and outer shell. Newer EPA stoves will have hotter firebox temps than the actual exhaust pipe, so flow around firebox is needed to extract heat.

 

Next time I’m on the roof I’ll take a pic

 

It actually got that high? Your set up has a liner that goes up the chimney? I had a plan that was for putting a wood stove in the fireplace in the event that moving was likely and leaving the liner in for an insert install. Then it seemed to stop there as it seemed less feasible. There is a Lopi Answer that is an insert that can be used as a wood stove if you prop it up on factory feet. The problem was that the maximum sf heating was about 1200 sf running it hard. The medium insert was more of a practical option as 1200 was the low. I don’t believe I will have huge issues heating as long as I get the heat circulating well, hence the questions about the blower being necessary. I wasn’t really informed on it but since the installer recommended LOPI over Iron strike which is a US stoves brand, I think that iced my options and decided on going with a company with a solid reputation. That being said I’m less worried because I will already be having a wood burner that will provide better results than what I have. It’s just likely that some adjustments will be necessary to provide more consistent results.

 

All installations by code require a liner to the top of chimney. The Inserts you’re installing are best with 6 inch all the way, most require it. If you don’t have a lower block off plate to hold insulation, or an insulated liner, the hot air rises to the top block off plate, it expands and contracts, breaking the seal or warping sheet metal as it expands.
Fisher as well as other copies were built and UL Listed to use the larger existing fireplace flue. Time has proven that installation (considered slammer) allowed too much expansion of flue gasses in chimney flue, allowing excessive cooling of flue temperature. You must stay above 250* internal temp to the top when smoke is present to avoid condensing of water vapor in flue allowing smoke particles to stick. This forms creosote rapidly, and is the reason for the code change.

 

Let me get this a bit more clear as I’m trying to understand what it is. I’m aware of the liner deal and in fact had to explain to family why this would be required: the heat of an insert today is not like the heat of a fire in the fireplace. So having an insert would be like having a rocket stove at the bottom of a chimney. Now that being said, liner is put in, flue flap is dismantled and often some brick tends to be removed? Once that is in place, usually the flue has some angle iron left over, then a block off plate is recommended to seal off the rest of the flue opening as the liner is situated in the chimney. Then here’s where I’m getting murky, is there needing an additional blockoff plate at the top of the chimney where the liner ends and the sheet metal cover meets the venting and then chimney cap goes on that?

Without trying to get off topic, I’m only aware of how my old wood stove before was installed they sent the stove pipe up the roof and made the “box” and the pipe was the usual 15 feet. This liner will be 25. Is the heat coming from the insert up the liner be too harsh on the sheet metal as a whole? I’m only hoping that the kit that is part of the liner is complete with this kind of plating if I’m conveying you correctly.

 

Yes, a fireplace needs a much larger flue since the opening is larger in the front to prevent smoke spillage. Exhaust gasses cool as they expand. Any stove will retain more heat having less to waste up the chimney to keep it hot enough to prevent creosote. (creosote wasn't a problem with a fireplace since they lost so much heat up the chimney, it stayed clean, and also didn't heat the house) Pre-fabricated metal chimneys for fireplaces are also rated with lower temperature fire rating even though they get hotter with normal use. They don't need to survive hotter creosote fires created by wood stoves. This is the reason you can't use a stove or insert on a fireplace rated chimney.

So along came Bobby Fisher, a laid off welder with the idea of making his own steel plate stove. This was the first major improvement over the cast iron fireplace Benjamin Franklin invented. Bob's stove was placed on the hearth sideways to save room in his small A frame home with a side 6 inch outlet. He made a steel plate across the fireplace opening with a 6 inch hole to put the connector pipe through and found how much more efficient it was. This was 1973. Within a few years, many were copying his patented stove, and he decided not to fight the imitators with law suits, and simply make a better stove than anyone else. In 1979 Fisher designed the Fireplace Insert. Others followed, but Fisher added brass or nickel plating, later glass doors....... and worked with insurance companies getting fire safety standards standardized country wide. By 1988 the EPA enforced smoke particulate size limitations. Baffles were designed to decrease smoke particles but could not reduce particulate small enough for the final regulations. They decided to go out of business instead of making a less efficient stove with a large outlet, the only way to make them burn clean at the time. Back then the competition was so great, you couldn't make a clean burning stove demanding a 6 inch chimney because people were using their existing larger masonry chimneys. Customers would simply buy someone else's less efficient stove with a large outlet to use their old chimney. When secondary combustion was invented, that leveled the playing field. All manufacturers had to require 6 inch chimney flues to physically make the new burning method work. (The stoves didn't put out enough waste heat to keep the large chimney above the condensing temperature).

A fireplace damper or other obstructions sometimes need to be removed. Whatever it takes to get a liner through the chimney. Sometimes the liner needs to be ovalized to get through a tight spot or turn. Others are straight up that straight stainless pipe sections can be screwed together like stove pipe as they are installed. (solid liner instead of flexible) Any stove new or old benefits from the correct size flue and insulating the inner flue pipe.

The block off plate is simply a sheet metal plate top and bottom that keeps the flue liner centered and closes the bottom from indoor heat rising and top from moisture from weather leaking down the flue. You can fill the void around liner with pour in insulation or use a wet cement like masonry mix around the liner. The object is
keeping the internal flue above 250* f. to the top. Any hotter than 250* is waste, any lower can form creosote. So that is far below the chimney fire rating temperature the liner must be capable of. External temperature at block off plate is about 1/2 flue gas internal temperature. (measuring surface temperature with magnetic thermometer or IR thermometer is about 1/2 internal flue gas temp). The reason you want an insulated liner is the easier it is to keep it hot, less waste heat is used to make the stove work, so more heat is available to radiate or convect into the home. **The gasses rising up the chimney create a low pressure area in the connector pipe and stove. This lower pressure area allows atmospheric air pressure to PUSH air with oxygen into the stove for combustion.** So the chimney is the engine that drives the stove. It is much more important than the stove itself.

The rain cap prevents rain and snow from entering flue and may contain a spark screen which is the first to plug up with creosote with cold wind blowing across it, allowing any water vapor to condense on the cold metal. They attach different ways to the liner or chimney top.

BHoller is a professional chimney sweep and installer that knows much more than I do about installation.

 

All installations do not require a full liner. Direct connect is technically acceptable but less desirable for a few reasons.
Any expanding air inside the chimney can exit at the bottom if there isn't a block off plate. Insert surrounds aren't air tight.

 

Not to be repetitive or beat a but I really think a blower in an insert is a must. I cannot fully heat my home without it. Only in shoulder season or to take the chill out of the house will I ever turn it fully off. Even then I usually put on low just to keep the air moving out and away from mantle/TV. Full disclosure in that I've never tried running fans to circulate the air so I am sure that can work. But getting that super hot air blown out and a way from the insert is really key to getting the air circulating and warming the other rooms.

Also if you have a TV mounted above the insert, having a blower is imperative, otherwise that hot air is potentially going to roast out that TV in time. With the blower on even at a low setting it pushes that hot air out and away from mantle and TV.

I have a deflector installed on mine & a pic of my block off plate. Above that sheet metal and around the collar is a bunch of roxul stuffed up there as much as I could stuff.

 

Nice deflector, but I'm not sure about burning human parts in your Insert.

 

So the insert was installed without any major issues. They said They were lucky and believe it has a lot to do with supplies and things just by hairs and strings came together. Without my understanding, since I thought the blower was not part of the insert as I thought to have it not on the quote but guess it just happened to be on there. Otherwise it’s better that the blowers were installed as other options would likely not have been sufficient in heating. Also I asked if they were going to put in a block off plate. They did but they did it at the Top Of the chimney. Great. I should have told them that it’s still going up the chimney, heating that and then coming back down. What I won’t argue with is how comfortable the house is. It isn’t hot but right at the middle at 65 is comfortable enough. Heats the upstairs well enough and I feel the heat as it travels upstairs. The moisture/damp cold has been fixed and hopefully there will be another cold snap to justify this as rifht now its hanging close to 40’s and 50’s.