Very lost on gas insert efficiency, please help

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GratefulBear

New Member
Sep 17, 2021
5
MA
Greetings forum,
I've been doing a lot of reading here lately but first time posting. When I started pondering getting a gas insert, I didn't think efficiency would be an issue. Gas furnaces can be so efficient. However, I was shocked to find the efficiency with an insert can go as low as in the 50's. Moreover, it is very difficult to find guidance on getting an efficient insert. Some of the manufacturer's make that info hard to find, I can't find any website that compares efficiency of the various brands, and I've spoken with two stores who had trouble getting me that information and one said they rarely get asked that question... We have an ideal setup to be able to heat our whole 2,300 sf open floor plan house with an insert as the fireplace/chimney is central to the house and by the areas we spend the most time in and like to keep the warmest. I also can't see pulling the trigger on something that has worse efficiency than our 40 year old oil furnace (80%). The best I could find was a Napoleon Roxbury 30 that is only 24000 btu but is 85% efficient, but has been discontinued <> We need something that is 38k plus with a good turn down ratio, but most importantly efficient. Can any of you fine folks help me out in my quest?
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,626
South Puget Sound, WA
First and foremost, it's going to depend on what fits in the fireplace, check dimensions. The Pacific Energy Tofino i40S insert boasts 78% efficiency and the Enviro EX35 touts 75%. I don't have a full listing, but for some other examples, the Quadrafire Excursion III is about 72% efficient and the QFI35FB around 75%, I recall the Jotuls being in the ~65% efficiency range with good turn down, Valor inserts average around 70%, same with Regency's E33.
 

GratefulBear

New Member
Sep 17, 2021
5
MA
The Pacific Energy is getting warmer (no pun intended). Thank you. Attached are the measurements. The back starts to taper gradually around 14" up. I'm not opposed to using a spacer trim kit if needed for depth.

Fireplace2.JPG
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,626
South Puget Sound, WA
Note that efficiency may vary with the output setting. For example, Lopi lists their 616 gas insert at 85% efficient, at high output. The P4 Canadian efficiency rating is about 73% on LP. Most of the efficiency listings above are to the Canadian rating standard.

That is a good-sized fireplace. It should handle most inserts.
 

GratefulBear

New Member
Sep 17, 2021
5
MA
Ah. That's a huge piece of information (that they may be using different standards for measurement). Good to know, thank you. The industry really makes it clear as mud. I like that Mendota appears to be more open about the efficiency and how it's measured. FV44i at 82% with P4 but not sure if it fits yet. Is there anywhere that lists all the different brands/models and efficiency? I tried searching for a Canadian govt site but no luck
 

Lennox65

New Member
Jan 29, 2021
73
New Hampshire
Greetings forum,
I've been doing a lot of reading here lately but first time posting. When I started pondering getting a gas insert, I didn't think efficiency would be an issue. Gas furnaces can be so efficient. However, I was shocked to find the efficiency with an insert can go as low as in the 50's. Moreover, it is very difficult to find guidance on getting an efficient insert. Some of the manufacturer's make that info hard to find, I can't find any website that compares efficiency of the various brands, and I've spoken with two stores who had trouble getting me that information and one said they rarely get asked that question... We have an ideal setup to be able to heat our whole 2,300 sf open floor plan house with an insert as the fireplace/chimney is central to the house and by the areas we spend the most time in and like to keep the warmest. I also can't see pulling the trigger on something that has worse efficiency than our 40 year old oil furnace (80%). The best I could find was a Napoleon Roxbury 30 that is only 24000 btu but is 85% efficient, but has been discontinued <> We need something that is 38k plus with a good turn down ratio, but most importantly efficient. Can any of you fine folks help me out in my quest?
Gas inserts aren't designed to evenly heat a 2300 sq foot area. They are labeled as "supplemental heat sources, and not intended to be the main heat source". The efficiency rating would be a moot point as you would be overheating the area closest to the insert to barely raise the temp a few degrees at the other side of the open concept room.
 

GratefulBear

New Member
Sep 17, 2021
5
MA
Gas inserts aren't designed to evenly heat a 2300 sq foot area. They are labeled as "supplemental heat sources, and not intended to be the main heat source". The efficiency rating would be a moot point as you would be overheating the area closest to the insert to barely raise the temp a few degrees at the other side of the open concept room.
I know they're not really designed for even heating and that's something we like about it actually. The fireplace is central to the living area (kitchen, living room, dining room) and we normally keep the thermostat off on the second floor as too much heat rises up there anyways due to the open layout. I don't understand why efficiency would be a moot point, as you put it. If you are overheating an area then either the btu's are too high or the turndown ratio isn't large enough. I'd rather pay less money per btu of heat output (and less carbon emissions). If efficiency is a moot point, then why not just buy cheap inserts that get 25% efficiency? Just seems like the industry is behind the ball and I bet part of that is gas inserts are typically bought by people who are well off and not as concerned with economics. It looks like the industry in the UK has caught on and they have (new) more efficient options there.
 

ABMax24

Minister of Fire
Sep 18, 2019
1,216
Grande Prairie, Alberta, Canada
Here's is the Natural Resources Canada list on fireplace efficiency: https://oee.nrcan.gc.ca/pml-lmp/index.cfm?action=app.search-recherche&appliance=FIREPLACE_G

One thing to note is fireplaces with a standing pilot light often have a much lower efficiency because it is assumed the heat from the pilot light does not enter the room and is wasted, with my gas fireplace this isn't the case as the glass stays quite hot with just the pilot light on and some of that heat enters the room. That being said my gas fireplace is rated at something like 55% efficiency, its auto ignition counterpart is about 70%, which is still a substantial amount of heat vented directly outside.

There are ways to may a gas fireplace more efficient, but issues then appear with condensation in the flue piping, which really limits the efficiency to about 80%. Granted this list does have more than a few models at 80%.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
26,168
central pa
I know they're not really designed for even heating and that's something we like about it actually. The fireplace is central to the living area (kitchen, living room, dining room) and we normally keep the thermostat off on the second floor as too much heat rises up there anyways due to the open layout. I don't understand why efficiency would be a moot point, as you put it. If you are overheating an area then either the btu's are too high or the turndown ratio isn't large enough. I'd rather pay less money per btu of heat output (and less carbon emissions). If efficiency is a moot point, then why not just buy cheap inserts that get 25% efficiency? Just seems like the industry is behind the ball and I bet part of that is gas inserts are typically bought by people who are well off and not as concerned with economics. It looks like the industry in the UK has caught on and they have (new) more efficient options there.
Gas fireplace inserts or fireplaces are not going to come anywhere near as efficent as a furnace. They are designed to have an attractive fire which absolutely is not efficient. Their fire is tuned to have a nice looking orange flame to imitate a wood fire. That isn't efficient. They have a large firebox with a relatively small heat exchanger unlike a high efficiency furnace which is mostly heat exchanger.

And you assumption that you can heat the whole house without over heating the space it's in as long as it's sized property just is not accurate. Your home requires a certain amount of BTUs to maintain temperature. With a space heater all of those BTUs have to come from one spot. That is going to lead to high temps near the heat source no way around it.

All that being said getting the most efficient insert available is certainly a good thing. But if your goal is to.reduce consumption and emissions as much as possible a properly zoned high efficiency furnace is the answer
 
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Lennox65

New Member
Jan 29, 2021
73
New Hampshire
I know they're not really designed for even heating and that's something we like about it actually. The fireplace is central to the living area (kitchen, living room, dining room) and we normally keep the thermostat off on the second floor as too much heat rises up there anyways due to the open layout. I don't understand why efficiency would be a moot point, as you put it. If you are overheating an area then either the btu's are too high or the turndown ratio isn't large enough. I'd rather pay less money per btu of heat output (and less carbon emissions). If efficiency is a moot point, then why not just buy cheap inserts that get 25% efficiency? Just seems like the industry is behind the ball and I bet part of that is gas inserts are typically bought by people who are well off and not as concerned with economics. It looks like the industry in the UK has caught on and they have (new) more efficient options there.
The technology has evolved greatly to increase efficiency. Open faced B vent gas fireplaces sucked heated room air up the flue. Direct vent fireplaces changed that but the early standing pilot units were still only marginally efficient. Some newer direct vent fireplaces have the ability to draw some of the heat from the fireplace and duct it into another room. The efficiency rating system is confusing and I have not wasted any time trying to figure it out. My customers are typically only concerned with a good looking flame.
 

GratefulBear

New Member
Sep 17, 2021
5
MA
Here's is the Natural Resources Canada list on fireplace efficiency: https://oee.nrcan.gc.ca/pml-lmp/index.cfm?action=app.search-recherche&appliance=FIREPLACE_G

One thing to note is fireplaces with a standing pilot light often have a much lower efficiency because it is assumed the heat from the pilot light does not enter the room and is wasted, with my gas fireplace this isn't the case as the glass stays quite hot with just the pilot light on and some of that heat enters the room. That being said my gas fireplace is rated at something like 55% efficiency, its auto ignition counterpart is about 70%, which is still a substantial amount of heat vented directly outside.

There are ways to may a gas fireplace more efficient, but issues then appear with condensation in the flue piping, which really limits the efficiency to about 80%. Granted this list does have more than a few models at 80%.

Thank you so much. I've used that site a lot in the past 12 hours. I'm partway through the process of getting quotes on a couple models and I'll update on here later
 
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