Decisions Decisions

[EvergreenKB]

Hi everyone. New member.

My Scenario:
Im in South PA where nighttime temps get around mid-teens to low 20s on average at night through the winter months. I've been using a Harman Mark 2 coal stove for the past 30 years to heat my home. I burn wood from 6 am to 8 pm and coal through the night. The Harman has been fantastic but after many years, it's developed a crack in the top of the firebox so it's time for a replacement.

Background
My house is 1800sqft, two-story and heats fairly well as the staircase is placed center of the house. My current chimney is 6". With burning coal, a single bucket will burn for about 8-10 hours and keep the stove temp around 300-400* until morning. In the morning, I can open the bottom door, get the coals red hot again, and toss a log on and the temp will jump pretty quickly. Even during the winter months, the house barely drops below 70* in the morning hours and is around 80* during the daytime when it's in the 20's-30's outside.

The Dilemma
I went to a local stove dealer for info on new stoves and originally inquired about a Hitzer 254 as it would be a direct replacement to my current Harman. I have no experience with the newer technology of the wood stoves and when the salesman heard I burn wood almost 75% of the time, he quickly began pushing a wood stove. Wood is free to me so it makes sense. No issues there. The salesman steered me away from any catalytic stoves and focused on secondary burn stoves such as the Quadra Fire's and Osburn's. My main issue is, will the wood stove carry heat throughout the night to the morning hours similar to a coal stove?

Preference
I don't mind waking up in a cooler house but my elderly father gets cold and uncomfortable rather quickly being on blood thinners. Coal has worked so well for so many years but the price keeps increasing and it won't be too long before legislation makes it harder and harder to get. I have 10 acres of hardwoods so it's easy to source wood. Pellet or Stoker stoves are not an option as I rather not have to deal with the electricity required to operate the stove. Without experience with the secondary burn or catalytic stoves, I'm open to either if they work.

Let me know what you guys think.

Thank you

 

[begreen]

A good 3 cu ft wood stove should be able to satisfy that need. In milder weather we burn on a 12 hrs reload cycle. In cold weather that drops down to 10 or even 8 hrs. depending on how hard the stove needs to be pushed. With good, dry, hardwood this cycle is definitely possible. In non-cats, the Lopi Liberty, Osburn 3500, Pacific Energy Summit LE, Jotul F55, etc. will get the job done. There are then hybrid stoves like the Regency 3500 and Woodstock Ideal Steel that can do the job. And as long as the stove only burns wood, the full catalytic Blaze King Princess should definitely be a contender. Of all of these stoves, the Blaze King will provide the longest continuous burn time.

 

[EvergreenKB]

A good 3 cu ft wood stove should be able to satisfy that need. In milder weather we burn on a 12 hrs reload cycle. In cold weather that drops down to 10 or even 8 hrs. depending on how hard the stove needs to be pushed. With good, dry, hardwood this cycle is definitely possible. In non-cats, the Lopi Liberty, Osburn 3500, Pacific Energy Summit LE, Jotul F55, etc. will get the job done. There are then hybrid stoves like the Regency 3500 and Woodstock Ideal Steel that can do the job. And as long as the stove only burns wood, the full catalytic Blaze King Princess should definitely be a contender. Of all of these stoves, the Blaze King will provide the longest continuous burn time.

I see a lot about long burn times but I don't see much in the way of people recording the stove temp over time. Radiant heat is more important to me than seeing red coals smolder for hours. Will these stoves keep a solid 400* stove temp for 10 hours?

 

[stoveliker]

Is radiant heat more important or BTUs shed into the room?

If the latter, a stove with a lower outside temp because of a convective jacket may work.

In the end BTUs in your room is what makes you warm. The efficiency of a stove is the ratio of BTUs put in (wood) vs BTUs into the room (with the rest going up the flue)

And those efficiencies are not significantly different for modern stoves.

My point is that a stove top of 400 F says nothing about how well the stove is shedding BTUs into the room when comparing different designs.

Of course given a fixed firebox, so a fixed amount of fuel (wood), a longer burn time will result in less BTUs per hour, and a shorter burn time running higher will result in more BTUs per hour.

 

[EvergreenKB]

Is radiant heat more important or BTUs shed into the room?

If the latter, a stove with a lower outside temp because of a convective jacket may work.

In the end BTUs in your room is what makes you warm. The efficiency of a stove is the ratio of BTUs put in (wood) vs BTUs into the room (with the rest going up the flue)

And those efficiencies are not significantly different for modern stoves.

My point is that a stove top of 400 F says nothing about how well the stove is shedding BTUs into the room when comparing different designs.

Of course given a fixed firebox, so a fixed amount of fuel (wood), a longer burn time will result in less BTUs per hour, and a shorter burn time running higher will result in more BTUs per hour.

If the stove isn't hot, it's not going to shed BTUs, so yes a constant 400*F stove temperature matters a lot to keep the air warm when fighting 15*F or lower night temps.

My home is drafty so a hot stove is a must.

When I think of 10-hour burn times, I keep thinking of how well anthracite performs. It has to be near impossible for wood to compare given the BTU/lb of wood is much lower than coal.

 

[stoveliker]

That is a misconception.
My stove has a second jacket. The outer surface that you can touch is far cooler than the inner surface where the convection air gets heated, transporting the energy to the room.

If you have only one wall, you're right, surface area and temperature (difference) determine energy transfer.
But for stoves with a second layer of metal and the same efficiency, the same BTUs get transferred through the room without having 400-500 metal that you can touch (except for the door).
They don't magically disappear... (My flue is cool...)

The volume of anthracite in a coal stove is far lower than the volume of wood in a large wood stove; the larger volume of the wood stove offsets some (not all) of the energy density decrease of wood as compared to coal.

More important, how much (weight) of coal did you burn in a night at 10 F?
That tells us BTUs needed and can point to a stove with the right volume to keep you warm enough.

 

[EvergreenKB]

40lbs of anthracite which is about 520,000 BTU.

 

[Todd]

That is a misconception.
My stove has a second jacket. The outer surface that you can touch is far cooler than the inner surface where the convection air gets heated, transporting the energy to the room.

If you have only one wall, you're right, surface area and temperature (difference) determine energy transfer.
But for stoves with a second layer of metal and the same efficiency, the same BTUs get transferred through the room without having 400-500 metal that you can touch (except for the door).
They don't magically disappear... (My flue is cool...)

The volume of anthracite in a coal stove is far lower than the volume of wood in a large wood stove; the larger volume of the wood stove offsets some (not all) of the energy density decrease of wood as compared to coal.

More important, how much (weight) of coal did you burn in a night at 10 F?
That tells us BTUs needed and can point to a stove with the right volume to keep you warm enough.

But wouldn’t a jacketed or shielded stove send more heat or btu up the chimney than a fully radiant stove? Kind a like single wall verses double walled pipe?

 

[EvergreenKB]

But wouldn’t a jacketed or shielded stove send more heat or btu up the chimney than a fully radiant stove? Kind a like single wall verses double walled pipe?

A double wall pipe is insulated to keep heat in. A jacketed stove would be a raised covering from the actual stove that acts as an air channel. Air circulates around the stove and is heated within the jacket. As long as the heated air can escape and cool air is introduced, it would work well to heat the home.

 

[stoveliker]

40lbs of anthracite which is about 520,000 BTU.

A 3 cu ft firebox can be loaded with about 475,000 BTUs, of course dense wood (e.g. locust, oak) is needed, not pine etc. and one has to load tightly.

 

[stoveliker]

But wouldn’t a jacketed or shielded stove send more heat or btu up the chimney than a fully radiant stove? Kind a like single wall verses double walled pipe?

No, it depends on the design.
Insulated systems are based on closed air pockets. Foam, double glazing etc. and double wall flue pipe.
Here the air pockets are not closed and designed to have air convect, movig heat into the room, which can be helped further by a fan mounted to the stove

They reach the same efficiencies (ratio of BTU into the room vs BTU up the flue) as stoves that shed relatively more via IR radiation.

 

[Todd]

When I removed my rear and bottom heat shields then filled the side shields with pea gravel my flue temps dropped (a sign of better efficiency?) compared to when everything was left open. The radiant heat is more pronounced and the stove seems to burn and heat my cabin better than before.

 

[EvergreenKB]

A 3 cu ft firebox can be loaded with about 475,000 BTUs, of course dense wood (e.g. locust, oak) is needed, not pine etc. and one has to load tightly.

That right there says there is little to no wiggle room to go hotter if needed.

Seems like coal is still the best option for those long hours to produce consistent heat.

 

[stoveliker]

If you burn 10 hrs you get 52000 BTU per hr, Id get 47500 per hr.
Max indeed.
If that's not enough you need a bigger stove to get that output AND last for 10 hrs

 

[EbS-P]

That right there says there is little to no wiggle room to go hotter if needed.

Seems like coal is still the best option for those long hours to produce consistent heat.

You can burn that load in 12, 8 or 6 hours. the high end burn rates for big stoves are almost always above 75k btus per hour.

 

[kborndale]

Keep in mind that burning wood is a second job if you plan to process your own wood. You can't just split wood and burn it, hardwood takes a minimum of a year after being split to be dry enough to burn, some species can take up to 3 years. You want to be two years ahead on your wood supply. And you very rarely can buy wood that is ready to burn even though every dealer tells you their wood is seasoned.

 

[EvergreenKB]

You can burn that load in 12, 8 or 6 hours. the high end burn rates for big stoves are almost always above 75k btus per hour.

That's a bold claim but I don't believe that to be true. Do you have info to back that up?

Here are the efficiency specs for the QF 5700. The EPA BTU Output shows a range that is much lower than the Peak BTU/hr Output. Peak BTU's is a rating during the 1st hour of the burn, which means it's not sustainable for any lengthy periods. It's not clear but I think the EPA BTU Output range is what the stove outputs after the 1st hour and settles into a steady burn over 15 hours (listed max burn time for the 5700). If you think of it this way, that is very unimpressive since the stove is going to be producing less and less BTU as the night goes on and the air temps get colder and colder.

I guess my issue is that I have burned coal for so long that I trust it far more than wood for long consistent heat. Coal doesn't spike in temperature and drop like wood does. It burns consistently for a very long time with no changes needing to be made during the burn. I would have to get a wood stove as a secondary to test its limits and build my confidence in one.

 

[begreen]

The EPA is more concerned with emissions than heat output so EPA testing is done with a fixed load of wood at fixed burn rates. It does not represent the maximum output capability or burntime.

Coal will provide a more controlled steady state of heat. A cast iron jacketed steel stove will mimic this behavior somewhat because the cast iron soaks up a lot of heat and then slowly releases it as the fire dies down. This reduces room temperature swing between loadings. The Pacific Energy Alderlea T6 and Jotul F55 are cast iron jacketed stoves. For yet more even, coal-like heating, consider the Blaze King Ashford 30. It is a cast iron jacketed and thermostatically regulate catalytic stove.

A big firebox wood stove will provide 12-14 hr burns in milder weather and 8 hr burns in very cold weather when it's being pushed harder for heat. The BK stoves are pure cat and an exception. They will provide up to 24 hr burns in mild weather when the BTU demand is low. This will drop down to as low as 8 hrs when the stove is being pushed hard for heat.

Note that any wood stove is going to need fully seasoned wood with a moisture content of 15-20%, internally measured, to perform well.

 

[EbS-P]

That's a bold claim but I don't believe that to be true. Do you have info to back that up?

Here are the efficiency specs for the QF 5700. The EPA BTU Output shows a range that is much lower than the Peak BTU/hr Output. Peak BTU's is a rating during the 1st hour of the burn, which means it's not sustainable for any lengthy periods. It's not clear but I think the EPA BTU Output range is what the stove outputs after the 1st hour and settles into a steady burn over 15 hours (listed max burn time for the 5700). If you think of it this way, that is very unimpressive since the stove is going to be producing less and less BTU as the night goes on and the air temps get colder and colder.
View attachment 331010
I guess my issue is that I have burned coal for so long that I trust it far more than wood for long consistent heat. Coal doesn't spike in temperature and drop like wood does. It burns consistently for a very long time with no changes needing to be made during the burn. I would have to get a wood stove as a secondary to test its limits and build my confidence in one.

My post should have stated peak btu /hour of 75k.

I think you are correct about the steady burn rate of coal. But if I wanted steady wood heat I’d be installing a BK. And the BK king if I had room for an 8” liner/chimney and could utilize 12 and 24 hour reload cycles.