Stove Efficiencies

[RyanF]

Hello,

I'm new to the world of pellet stoves, and I was wondering if it is possible to accurately calculate stove efficiencies with off the shelf tools. I have an IR digital thermometer, and I have been monitoring exhaust temps and heat exchanger temps, but I'm not sure if this is an accurate approach. I also have access to thermocouples and data loggers if needed. I guess I am curious how one would go about figuring this out.

Assuming that new pellet stoves acheive near complete combustion, shouldn't it be possible to extract almost all the heat from the exhaust considering that it is forced and doesn't require a draft like a wood stove?

Ryan

 

[BDPVT]

Are you trying to determine your stove's efficiency rating or what combination of settings and fuel give you the best heat output?Efficiency is defined as the percentage of available heat in the fuel that is actually delivered into the room. This is typicaly done in a laboratory setting under ideal conditions. You cannot easily duplicate this level of testing, But a real world comparision of heat output is very doable. Sounds like you have the tools you need. First run your stove and take some measurements to establish a baseline. Then just set your stove up the same way for the same amount of time for every test and change only one variable at a time, air to fuel ratio as an example. Standardize your measurements of exhaust air temp and convection air temps and compare the difference against your baseline. Should give you a good idea of what settings work best. Have fun!

 

[jtakeman]

Due to the available tax credit for new stoves purchased. Most of the manufactors have sent there stoves to the EPA for independent testing. They should have the info you need for the stove by request or just visiting there site. My stove wasn't listed at the site but I was ablr to get the results by email from the manufactor. The EPA testing is much more stringent than the testing the manufactor has done in the past. So the numbers seem more real world than inflated.

Are you trying to compare stove to stove?

By the way welcome to the forums.
jay

 

[MCPO]

I think it`s very difficult if not impossible for the average person to do this with any degree of accuracy. Far too many variables and inconsistancies in the pellet fuel itself and burn rates not to mention the quality , accuracy , and cost of his test equipment.
Then we have to consider the :
1.......efficiency of the burn
2.......efficiency of the heat exchanger
And how about emissions, flue temperatures , and exactly what fuel rate produces the best overall efficiency for heat transfer vs heat up the flue..
Throw in what speed is best to set the distribution blower at.
Nah, Net efficiency itself has to be hard of not impossible to arrive at with any degree of consistancy.
The best any of us can do is to discuss our stoves (ad nauseum) like we have been right here and eventually we come up with a fair assessment of most brands and models. I`d bet it is more reliable information than the manufacturers print in their brochures .

 

[RyanF]

I think it`s very difficult if not impossible for the average person to do this with any degree of accuracy. Far too many variables and inconsistancies in the pellet fuel itself and burn rates not to mention the quality , accuracy , and cost of his test equipment.
Then we have to consider the :
1.......efficiency of the burn
2.......efficiency of the heat exchanger
And how about emissions, flue temperatures , and exactly what fuel rate produces the best overall efficiency for heat transfer vs heat up the flue..
Throw in what speed is best to set the distribution blower at.
Nah, Net efficiency itself has to be hard of not impossible to arrive at with any degree of consistancy.
The best any of us can do is to discuss our stoves (ad nauseum) like we have been right here and eventually we come up with a fair assessment of most brands and models. I`d bet it is more reliable information than the manufacturers print in their brochures .

Hello Gio,

The variables you mention are exactly what I would like to know. I have a well insulated home, and I run my stove on the lowest setting. I was wondering if it would make more sense to run it hotter for shorter periods of time, or on a lower setting all day. I'd like to run it at 'optimal' or close to optimal settings. By the way, what do people say in general about Jamestown Stoves? I have the J1000 model, so far it seems very well built and i am happy, but its just my first season.

Ryan

 

[jtakeman]

I think it`s very difficult if not impossible for the average person to do this with any degree of accuracy. Far too many variables and inconsistancies in the pellet fuel itself and burn rates not to mention the quality , accuracy , and cost of his test equipment.
Then we have to consider the :
1.......efficiency of the burn
2.......efficiency of the heat exchanger
And how about emissions, flue temperatures , and exactly what fuel rate produces the best overall efficiency for heat transfer vs heat up the flue..
Throw in what speed is best to set the distribution blower at.
Nah, Net efficiency itself has to be hard of not impossible to arrive at with any degree of consistancy.
The best any of us can do is to discuss our stoves (ad nauseum) like we have been right here and eventually we come up with a fair assessment of most brands and models. I`d bet it is more reliable information than the manufacturers print in their brochures .

Hello Gio,

The variables you mention are exactly what I would like to know. I have a well insulated home, and I run my stove on the lowest setting. I was wondering if it would make more sense to run it hotter for shorter periods of time, or on a lower setting all day. I'd like to run it at 'optimal' or close to optimal settings. By the way, what do people say in general about Jamestown Stoves? I have the J1000 model, so far it seems very well built and i am happy, but its just my first season.

Ryan

What your trying to do, Can be done without all the fancy testing. Your goal is to use less pellets. Correct?

Run the stove one day like you do now. Use just one bag or the days supply of pellets. Try to pick a similar temp day and do the same but with the stove on Auto/Off setting and stat. Try to maintain the same temps. The way that uses less pellets is what you want to use. Or the way that feels more comfortable.

This is what I did and I found in the fringe to use Auto/Off and the cold to use Hi/Lo setting. Auto/Off saves me pellets on the warm days. House is not over heated when I get home. Hi/Lo house is more comfy and stove isn't working as hard to bring the temp back up. I also found if I put the hottest pellets I can find in the cold really help save them. The colder burning pellet require more fuel burned to keep the same temp. The testing I did on that is here.

https://www.hearth.com/talk/threads/42511/

There will be more to come on those.

Trail and error. A good thermometer and patience.
Just mt 2
jay

 

[BDPVT]

I think it`s very difficult if not impossible for the average person to do this with any degree of accuracy. Far too many variables and inconsistancies in the pellet fuel itself and burn rates not to mention the quality , accuracy , and cost of his test equipment.
Then we have to consider the :
1.......efficiency of the burn
2.......efficiency of the heat exchanger
And how about emissions, flue temperatures , and exactly what fuel rate produces the best overall efficiency for heat transfer vs heat up the flue..
Throw in what speed is best to set the distribution blower at.
Nah, Net efficiency itself has to be hard of not impossible to arrive at with any degree of consistancy.
The best any of us can do is to discuss our stoves (ad nauseum) like we have been right here and eventually we come up with a fair assessment of most brands and models. I`d bet it is more reliable information than the manufacturers print in their brochures .

Hello Gio,

The variables you mention are exactly what I would like to know. I have a well insulated home, and I run my stove on the lowest setting. I was wondering if it would make more sense to run it hotter for shorter periods of time, or on a lower setting all day. I'd like to run it at 'optimal' or close to optimal settings. By the way, what do people say in general about Jamestown Stoves? I have the J1000 model, so far it seems very well built and i am happy, but its just my first season.

Ryan

Gio is right. Accurate measurements of efficiency are dependent on many variable and are best done in a lab under controled conditions. I make my living doing this sort of thing. Correct me if Im wrong, but it sounds like you are trying to determine the most efficent way to run your stove. Nothing fancy, just lots of trial and error testing and data collection should get you there. Many on this forum have done the same.

 

[RyanF]

I think it`s very difficult if not impossible for the average person to do this with any degree of accuracy. Far too many variables and inconsistancies in the pellet fuel itself and burn rates not to mention the quality , accuracy , and cost of his test equipment.
Then we have to consider the :
1.......efficiency of the burn
2.......efficiency of the heat exchanger
And how about emissions, flue temperatures , and exactly what fuel rate produces the best overall efficiency for heat transfer vs heat up the flue..
Throw in what speed is best to set the distribution blower at.
Nah, Net efficiency itself has to be hard of not impossible to arrive at with any degree of consistancy.
The best any of us can do is to discuss our stoves (ad nauseum) like we have been right here and eventually we come up with a fair assessment of most brands and models. I`d bet it is more reliable information than the manufacturers print in their brochures .

Hello Gio,

The variables you mention are exactly what I would like to know. I have a well insulated home, and I run my stove on the lowest setting. I was wondering if it would make more sense to run it hotter for shorter periods of time, or on a lower setting all day. I'd like to run it at 'optimal' or close to optimal settings. By the way, what do people say in general about Jamestown Stoves? I have the J1000 model, so far it seems very well built and i am happy, but its just my first season.

Ryan

Gio is right. Accurate measurements of efficiency are dependent on many variable and are best done in a lab under controled conditions. I make my living doing this sort of thing. Correct me if Im wrong, but it sounds like you are trying to determine the most efficent way to run your stove. Nothing fancy, just lots of trial and error testing and data collection should get you there. Many on this forum have done the same.

I guess I am just trying to reduce pellet consumption at the end of the day... but in the mean time I think it would be interesting to measure and report back to the community my findings. I also work in a lab, so I have access to some fancy equipment. In particular we have a multi channel thermocouple data logger which takes ordinary thermocouple wiring. I could monitor intake air, exhaust air, heat exchanger temp, room temperature etc. all at the same time. It would be interesting to see how it performs under less controlled situations.

 

[jtakeman]

I would be interested in the results. Maybe we could learn from your test's.

Wish I had some parameters for you. To techie for me.

Jay