Stove Size Question

[dpecota]

Hi,

I am interested in sizing a wood stove. I have a log cabin which is 24 x 52 with two stories. It is 6 inch softwood logs and has an R value of ~8.0 on the sides. A 24 x 30 section is ¾ wide open on the first floor and has a 12 x 30 loft on the upper floor. The peak if the vaulted ceiling is at least 20 feet high. I do not know what insulation is in the vaulted ceiling. The skylights indicate a framing thickness of about 6 inches.

See attached image for drawing.

The fireplace is 40 w x 30.5H x 30D with a 12x12 outside masonry chimney at least 20 feet from the top of the fireplace. I should be able to reline with either 8x8 insulated or 6x6 insulated easily. I live in Bethlehem Township NJ. It is considered Southern North Jersey. I have a Yukon-Eagle oil wood combo furnace in the basement. It is rated at 1gph oil. I used 1500 gallons of the first year and 1200 per year the last two years burning 3 cords of dry slab wood. I keep the house at 68 during the day and 62 at night. If the temp outside is less than 42 the furnace cannot keep up with heat demand when burning wood. However it is nice in “warmer” weather, I only need to visit the furnace a few times a day and the house is toasty. I only burn the wood in the early and late season. The furnace has a 3.5 - 4 .0 fire box and an upstairs thermostat controlled damper that is either all open or closed. I suspect its efficiency. It is sold as a wood stove with oil back up. The oil furnace is exempt from the required AFUE efficiency tests and the wood stove portion is not EPA certified. I would like to reduce my oil consumption to less than 500 gal, bump the temp to a 72, and not have to burn wood in the furnace and stove at the same time. I expect to burn 6.7 cords of slab wood to displace the 1000 gal of oil based on my current oil input btus. If the wood stove is 20% more efficient than the furnace (I hope) then wood consumption gets closer to 5 cords.

What size fire box do I need?

The stove will be placed in the fireplace. My wife does not really like the look of inserts(me either). My wife will yield if it is the only way to go. If it is free standing convection design on all sides except the front is sort of desired/required?

Are there many 5 sided convection free standing stoves available?
Searching the net gets tiring.

Note: Front to back loading would be nice. The Yukon-Eagle has it and it is easier to place wood through its relatively small door than putting wood in the fireplace crosswise.

Thanks,

Dean

 

[DriftWood]

Heating in winter is not just a stove thing. How air tight is your house? How much insulation is in the walls and roof?

The volume of your house is the same as a 2496 sg foot home. The open loft will be easy to heat. You will need cealing fans to mix the hot air to get it down to the ground floor. Put them in now as the will help even with your present set-up.

So do you want to burn 24/7 or just when some ones home?(how fast do you want heat out of a cold stove?) Do you want a cat or non cat stove? Do you like castiron , steel or soapstone stoves? That said bigger is better if you want 72 inside and it is subzero outside.


Do you want a blower running to get heat out of a insert? Im with you and your wife on this one, a Free standing wood stove in frount of the old fire place. This is what I did.

https://www.hearth.com/talk/threads/3106/

 

[BrotherBart]

Driftwood that is still the nicest stove and hearth installation I have ever seen.

 

[Gooserider]

Sounds like your first priority really ought to be improving your insulation and weather sealing - R-8 is pretty bad as such things go, and who knows what else you could bump up. Anything you can put into insulation will pay back in less wood and oil burned and a much more comfortable house.

Next I would agree that the biggest firebox stoves is what you should be looking at. I would also suggest that you should avoid putting the stove inside the fireplace, since it's an outside fireplace judging by your floor plan, any heat radiated into the fireplace is mostly going to warm up the wildlife... I would block off the front of the fireplace and put the stove in front of it, as that will give you much more heating.

Ditto on the suggestion of ceiling fans if you don't already have them.

Gooserider

 

[jpl1nh]

My understanding is that insulating a log cabin is pretty tough unless you want to give up the aesthetics of logs on the inner walls and cover them ove with a second wall. However, Goose and Driftwood are right, insulation is a huge factor. Having said that, in your current situation, radiant heat such as a soapstone stove might work a bit better for you. If you do choose to go with something more convective, ceiling fans would be an immense help dispersing that heat. They will certainly help even with radiant type heat as well. A Woodstock Fireview or Hearthstone Mansfield would be good choices

 

[wg_bent]

ONe of the problems you'll run into with a stove is that the poor insulation of the home will cause large differences in the temp around the house. I agree that plugging the holes is going to be a big help.

You should also look at stoves with blower options to get the heat distributed more. A pure radiant stove is great in the room it's in, but natural convection currents are needed to get the heat around the house. But in your case, those currents are also set up by the drafts and poor insulation of the home. Something like a PE summit with a blower would work.

 

[begreen]

Dean, does the house have a basement? If yes, is the basement insulated? Is the ductwork insulated? If not, I would start with insulating the ductwork. That can boost duct temps significantly.

Also, check those glass sliders carefully for leakage. If you can do without them for the winter, consider covering them with clear plastic in the cold months.

 

[dpecota]

Thanks for all input.

There is not much hope of insulating the walls. They are the modern milled logs which are pretty much square with some channels and recesses where they rest on each other. I do not consider covering them up an option. They have a really nice look.(I clearly pay for it) I'm stuck with the r8 of six inch soft wood. The windows and sliders are all double pane type and seal pretty good. I replaced weather stripping around the entry doors and they are pretty good also. I could easily cover one of the sliders in the winter. The other one we use to feed the dogs and down to the back yard.

The basement is 12 inch thick block. The house has a walk out basement so half is exposed to the air on the outside. The heating ducts are uninsulated. I thought about insulating and better sealing the heat supply ducts in the basement in the past. You can see dirty trails at some joint places where air escapes. I looked into one of those whole house duct sealing services but it was over $1000.00. Maybe I should tape joints and insulate the ducts myself. Unfortunately they are butted up to the joists which makes it harder to add insulation on the topside. The duct sealing service claims large efficiency gains are possible. I will re-examine this. It does not seem overly warm in the basement in the winter unless I have been using wood in the furnace. I would like to limit the oil portion of my heat input to 25% of my needs minimizing the effect of the forced air systems inefficiency.

I am mostly concerned with buying too large or small a stove. If my current oil usage is overly estimating heat need due to uninsulated ducts and an inefficient furnace I may install too large a stove. My wife said she could deal with the look of the Kuma sequoia insert but it is large. It is five sided convection design with a plate steel outer shell. It looks like a tank. With an insert I assume I will loose the diminished (due to the outer shell) radiant component on the 5 sides to the fireplace. I wonder how much loss it represents. The Kuma also requires an 8inch liner which restricts future choices if it turns out to be too much. I like the look of the Lowes bigger plate steel stove. I looks to be mostly radiant but does have side heat shields. Do they make it more convection like?. I do not know about the bottom. The price is good though. I looked at the Summit's website. I would need a short leg option which I did not see in order to fit the free standing. We dont' really like the look of the insert. I may be beyond look and have to go for function at this point.

The Summit and Lowes advertise a 3.0 and 3.5 fire box, the Kuma is a little bigger with 3.9. Are they too much?

What does the heat output curve look like for a wood stove? I know it is high in the beginning after the initial ramp up and then drops off greatly at the end. 3.5 cuft * 148500 btu/cuft = 519539 btu. 519539btu / 10 hr = 51900btu/hour over ten hours. If the heat distribution is stacked in the beginning will I get blasted? Can I mitigate it some with the stoves air supply? I expect on/off heat based on my experience using the Youkon-Eagle. I suppose there is a sweet spot between managing the peak output and reducing the amount of wood feeding. That is really where I want to be.

Thanks,

Dean






Dean

 

[stoveguy2esw]

Driftwood that is still the nicest stove and hearth installation I have ever seen.

i gotta agree with BB, WOW thats spectacular , you should be proud!

 

[begreen]

Insulating the ducts will help considerably. This might be your best first investment. It will pay off in reduced oil and wood consumption and will extend the usable season of the wood furnace. There can be a lot of heat loss (>50%) on long uninsulated runs. Once you're set up for it, the job goes pretty smoothly. Start on the longest runs first. Where the duct is tight to the joists, look to see if the hanger strap can be lengthened by an inch. Or some times it can be temporarily undone while wrapping the duct, then replaced once the insulation is in place. FWIW - the supply ducts should not be tight to the joists for the first 6 feet leaving the furnace.

This may sound like a silly question, but is the slab wood dry? There is much more heat in dry wood. If the wood is wet or green, it will burn a lot cooler.

 

[stoveguy2esw]

"The Summit and Lowes advertise a 3.0 and 3.5 fire box, the Kuma is a little bigger with 3.9. Are they too much? "


the lowes unit i likely mine, BB has one in a fireplace install, his is BB brown though , which is somthing he did ,( i actually like the color) with your lack of "r factor" you would be well served with a 3.0 cf firebox or bigger IMHO. the 50-snc30 at lowes is our 3.5CF firebox unit, the PE summit is an excellent choice a well, you might also look at the large blazeking , although if there is a firebox that could possibly be too big thats the one , the thing is huge!! nice unit , but the biggest restriction is whether it will fit and be connectable. with this in mind the unit may end up having to be a rear flue capable device. i hope this helps ya , as for the other units ive mentioned , there are several members who have them , as for the 30 , i can talk to you about it if ya want , and BB might could give you some insight as well as his is a similar install to what you are proposing

 

[BrotherBart]

I have been watching the thread. The 30-NCL would be a great stove for them. They would need to get it shipped with six inch legs instead of the nine inch standard ones for it to fit that fireplace. I haven't chimed in because I grow a little tired of people telling me the stove isn't this, the stove isn't that. We love the the big sumbitch. That's all that counts in this house. Mike sells stoves. We don't

The 30 in a fireplace is just dog nuts at heating. Do it right and it will produce heat out of there that no insert on the planet can match. The blower mounted on the back shoots the warm air straight across the top of the stove across the room for distribution to the rest of the house. Want less heat, build a smaller fire. No worry about getting it hot enough to engage a cat. Want the warmest house you ever saw kick'er up to six hundred with the blower running and I can assure you that at least 2,500 sq. ft. of two story house is going to be warm on a 11 degree night. Been there, done that. Without any Banzai 850 degree burning. Get a little lazy under the covers and it is possible to finally get up and the blower still be going with a stove top temp over 150 degrees 14 hours after you loaded it. And the bricks surrounding the fireplace stayed warm for hours after that.

Lot of stoves out there but this one deserves a look. It ain't the thickest steel on the block or the shiniest dude in town but it is the biggest most versatile hunk of steel you can fit in that fireplace. Will it last 20 years, I don't know. I doubt that I will either. The ash pan isn't huge but there ain't a heck of lot of inserts, I only know of one, that even has one.

Outside of that I have no opinion. :coolsmirk:

PS: As to BB brown, it is goldenglow brown the same as the Harmans.

 

[dpecota]

I think in have to go with an insert. I cannot find a ~3.0 fire box free standing that will fit in my fireplace. On paper some would fit but it would be too close for my liking. I looked at the basement ducts again and it reminded me why I dismissed it in the past. Both the supply and return are right next to each other. Even worse it looks like the installer made one strait line of hangers with the supply on one side and the return on the other. Each hangers is bent to the desired direction, screwed into the duct, and trimmed to 1 inch. I cannot access the hangers where they are attached to the joist have no adjustment with what is exposed.

Thanks to all for the inputs.

Dean

 

[BrotherBart]

How short does the stove have to be for your liking?

 

[dpecota]

26" would be about as the highest. I examined the fireplace again and the back wall starts to slope inward pushing taller stoves out further in the front. The front hearth is field stone which is a little uneven and up to 3/4 inch higher than the level brick "inside" of the fireplace. I took a tape measure and looked at the Englander at Lowes this weekend. I do not think the dimensions in my fireplace are as good as yours for the stove. I need a shorter wider stove.

Dean

 

[BrotherBart]

Ah OK. With the six inch legs the 30 is 27" at the highest point of the stove body and 28 3/4 at the flue collar.

Good luck with the stove hunt.

 

[begreen]

Sounds like an insert or at least a rear-exit stove will be needed.

 

[BrotherBart]

Actually the 30 is a fit for it. The stove is 28 inches deep but you don't want the whole stove shoved back in the fireplace. Only enough to line up the flue collar. About half of it for that fireplace. It is deeper than mine is. I think it is best to leave the half in front of the step-top outside of the fireplace for making radiant heat and coffee and breakfast during power outages. You connect the liner with a 15 degree stainless elbow.