Thermal mass

No need, I'm happy with my setup
Even if I bought a cat stove I would keep the block

 

Checking back in after almost 3 weeks of burning with the barometric damper installed. I am getting longer burn times and have much better control when I need lower heat output from the stove. I can't say that it doubled the burn times, but it is longer at a lower more steady temp than before. I'm suspecting a little less wood being used, but I can't really tell yet till we get into Jan / Feb. on cold nights I can get it to run at 400 / 450 for about 4-5 hours with a slower ramp down which is much better than the 500 / 550 for 2-1/2 hours like it did before with a rapid decline in output after that pulse of high heat.

I'm very glad I installed the baro damper and would recommend one to anyone with a chimney taller than 20' where the stove isn't performing quite as expected. As brenndatomu mentioned, it has tamed this chimney's high draft issue.

I cleaned the chimney today to ensure there wasn't any extra creosote build up due to the lower chimney temp near the top. I saw no extra build up at all. I had cleaned the chimney at the beginning of the season so I wasn't expecting much anyway. Maybe a cup of creosote and 1/3 of that was larger chunks that were dried up and scraped off the bottom of the clean out door.

 

I would not advice everybody with a flue 20' and taller and a misbehaving stove to use a baro; only those who have flue temps to spare, i.e. that are high enough to be diluted and not get too low.

 

Specifically an EPA stove on a tall chimney and burning dry wood (actually dry, not the "seasoned" stuff many try to burn)
If a person has an uninsulated chimney, wood not truly dry, an old school stove, or someone trying to burn "low n slow", those people need to avoid a barometric damper.

 

Well, how you liking the baro now MAF143?

 

I'm liking the better control over the fire and the longer burn times it has provided for my installation here. But at these temperatures this week I wish I had a second woodstove at the other end of our basement feeding the return air duct over there also... But I'm not going to install another when it would only get used 2 or 3 weeks out of the year when we get the bitter cold temps. I'm OK with the furnace kicking on some to assist the stove in keeping us cozy... It's a big house for a single stove to keep warm especially from the basement. I have about $2k in this stove and chimney set up and the convenience of having all the mess contained in one corner of the basement with a walk out door within 4' of the stove keeps my lazy butt smiling...

I've often thought I would like a furnace style stove (Kuuma) or an outdoor wood burner, but with this current set up working as well as it does, I'd rather put that capital investment into some solar panels on the roof (I've been saying this for years now).

 

Yeah they are pricey, but they are a buy once cry once purchase...been running mine pretty hard here the last 24-48 hours (still not set on high though) burning down coals right now, house at 71.2* when I got home at 4.

 

After a very brief search, I found this.


"For thermal mass to make a difference - you need A LOT of thermal mass.

The measure of how much heat a material can absorb is called "specific heat". The specific heat of concrete is between 0.20 to 0.28 Btu/lb per ºF. Let's use the best case scenario of .28.

That means that you raise the temperature of one pound of concrete by 1ºF when you add .28 BTU of heat energy. Every 1 lb block, warmed 1ºF will also give back .28 BTU of heat. Energy in = energy out.

To Demonstrate how much concrete is really needed, let's say you have 1,000 pounds of concrete surrounding your stove. You fire up the stove and over several hours, you raise the temperature of that concrete from 70º to 120º. That's a 50º temperature rise.

50º x 1000 lbs x .28 (specific heat) = 14,000 BTU of stored energy. Sounds like a lot. But if you have a small house in a colder climate that requires 50,000 BTU of heat per hour to keep warm, you can warm the house for about 20 minutes after your stove goes out.

Where thermal mass does help, at least a little, is if you have a big mass that can be warmed by the sun all day. That doesn't require you to add energy from your stove. But even then, the mass needs to be tens of thousands of pounds and you really don't get much back."



Now I'm sure you can fudge these numbers around to try to justify your position on thermal mess, but at some point you have to admit to yourself that it isn't working.

I wonder why the stove was never placed in the basement?

But, it all seems to boil down to throwing good money after bad. Get that place insulated properly and retain the BTU's that are being introduced into the dwelling.

Here is another quote that seems to apply in this case.

"Adding thermal mass does not increase heat. If you want a house that stays warm for longer you need better insulation. What heats your home is the BTU's from the fuel you burn. What makes it get cold is the heat transfer to the outside. Slowing that heat transfer is what insulation is all about.

If your stove does not burn all night I suggest you get a better stove.

No magic bricks, copper shields, soapstone, oil filled radiators or any other method of heat capture can increase the amount of BTU's a stove makes."

 

I probably do have around 1k of concrete.
Stove is not in the basement because I originally put a propane furnace down there for backup. It exhaust into chimney, illegal to run a wood fired appliance in same chimney.
Propane company told me I had to buy 800 gallons a year to keep my tank.
I told them to come get it, I ain't buying no 800 gallons.
I'm not an idiot, I know insulation is your best bet.
If you actually read my posts instead of just assuming chit you would see that we spent somewhere around 60k on the house last year, including sheathing and insulating.
I don't have the money to dump into it right now, my thermal mass setup cost me very little as I had most materials on hand already.
The blocks help us stay about 5f warmer.
A big problem is our 105yr old single pane windows. Theres a whole wall of them right by stoveThe wife's obsessed with them I'm not allowed to cover, block or change them.
I'm smarter than you think, and your constant harping about my temps makes me think you ain't got nothing better to do with your life than post on a woodstove forum about how superior you are

 

This is not my forever home, believe me when I build it it will be extremely well insulated and designed to heat with wood.
I'll still only keep it at 65 or so anything above is to hot in the winter.
I get plenty of heat in the summertime
Even if I was a millionaire I wouldn't have a/c people been fine for million years without it

 

yooperdave
Could your stove heat 3k sqft with huge single pane windows and 0 wind break from the west?
If I had the biggest model blaze king I still doubt I could get this house up to 75
When we moved in it would literally blow snow into the basement, and on windy days we had so much wind penetration we had a breeze inside
My stove does burn all night it has quite a large firebox

 

The rooms I have remodeled had literally 0 insulation on the exterior walls.
I have added as much as possible to the rooms I have remodeled.
Our kitchen is the next big project, it is on the west side of house. And is probably 5/8th of that sides wall
I expect to find 0 insulation so that will help, but gotta save up probably 10 to 15k to do it the way we want ( that's with me doing the work).
I mow grass for a living and have 2 kids it takes a while to save

 

I have read many of your posts and base my responses on what you yourself have admitted publicly.

Packing as much insulation as you can into spaces is not the best way for proper performance from insulation. "Fluffy, not stuffy" is the phrase to remember.

What ever heat source you use, retain those btu's inside by properly insulating! $60K would have insulated that house many times over-walls, attic and joist ends.

I hope you installed a high efficiency LP furnace as it can add about 20% more return on heating and energy/tax credits are available.

Regarding your windows, someone has already suggested using the heat shrink plastic film over the windows to help with the heat loss; Have you tried that? They are very attractive windows, I see why you want to keep them. Having the enclosed porch on the other side of the windows helps out enormously with the heat transfer to the outside. Maybe put the plastic film on the porch windows instead?

Thanks for the compliment of me being superior; that was nice. As far as the "harping" part of the same comment, I'll ask you this.

What are you doing on this forum? Did you come here for help? It wouldn't seem so since any advice offered, that is contrary to your agenda, isn't heeded.

You have to remember that there are many members here that have been burning for decades and decades. All their lives. We have experienced many of the same issues you are going through right now. Let our experiences help you out by taking shortcuts to greater comfort.


"Could your stove heat 3k sqft with huge single pane windows and 0 wind break from the west?"

I have a wood furnace and a wood stove. At least 2 miles of unobstructed prevailing winds from the west. 3400 sq ft. Loss of power and relied completely on the wood stove only (in the basement) for afternoon, evening, overnight. Temps dropped about 6 degrees. The big difference is insulation.

I will be more than happy to continue this back and forth in a PM if you choose.

The experience on this site can help but you must be willing to listen.

 

I truly think he's just trying to help you see it from a different perspective rather than living in the cold and saying, "ehhhh, it isn't that bad". With the temps you list on the other thread, personally, it sounds terrible. If you were my best friend, i don't think I'd come and visit in the winter.

Anyway, this house I'm in didn't start the way it is now. When i bought it i relied on a fuel oil furnace for heat. Tank was outside and I'd wake up to the fan blowing low 60° air and no fire in the furnace. Fuel line was froze up.

So i started supplementing with wood heat. The wood stove was already installed. Didn't have dry wood but made the best of it.

To my point though. My stove backs up to a concrete chimney with an exposed decorative brick wall to hide it. Said wall of brick is about 3" wide x 20ft long and 8ish feet tall. Add to that the whole house is on a slab. I would guess about 3" thick and the concrete all around stove is exposed.

That is what i attribute the "smooth" temps in my house too cause the temp doesnt just drop once the fires out. It just helps smooth the high/low swings of the stove.

Now to your window problem. I have 8 (see picture) 4x6 windows and a sliding door on the one side of the house. Granted its facing east and they are double pain but the windows are from the late 50s.



There's no attic here, it's all valted ceilings. The house originally had a tar type built up roof. Removed that and installed 4" rigid polyiso foam. I could tell a huge difference the first winter. A tremendous help but not the best.



When it gets below about 15°f, even an inch or two of snow on the roof makes a difference. 4-6" of snow and blow 15 temps are just as easy to heat this house as when it's 30+ and no snow.

My point is that thermal mass works but not as easily as proper insulation. I would guess that thermal mass is most noticeable when the structure is not sealed well and the heat just leaks out.

 

Here is where my money has gone
Insurance from softball sized hail
Roughly 27k got us a new roof and siding

Out of pocket
5k to have them completely sheath house in osb under siding, before it was diagonal 1x6s with gaps between all of them (our wind problem)
10k for main line sewer replacement.
These to things I did not do myself

What I have done myself with 0 help ( so no labor cost)
Insulated attic
Replaced knob and tube wiring through whole house besides 1 circuit between floors.
Redone upstairs bathroom including main cast iron stack replacement from basement wall to roof all plumbing, electrical and insulating.
Converted downstairs bathroom into big walk in pantry
Including insulating ,repair exterior framing, repairing floor joist framing, all electrical.
All plumbing above basement has been redone.
Installed natural gas furnace then converted it to propane
Installed woodstove, hearth, chimney
We have sunk so much money into this house in the last few years we just done have it to do projects right now.
Wife has stopped working to be a better mom so the expendable cash is tight

My wife won't let me cover her windows
I know I need to insulate, the exterior walls, that gets done as I slowly remodel.
I have not gotten a quote to get them blown in.

I'm on this forum to see other peoples woodscores, stoves, trees ect ect.

I get there are many much smarter people than me.
In 3 yrs of burning I have gone from a pot belly stove with furnace, to only wood, and our temps get better every year.
90% of the time we are decently comfortable 50-65f
People freaking out over temps in the 40s is just funny to me.
Y'all can tell me how bad of a father I am, not doing a mans job ect ect ect.
I'm not insecure about myself, or my role or my family.
But posts like that tell me the posters are insecure about their position in life.
I'm proud of my family and my life and how I provide.

 

You sure have (and are) worked hard.
That makes for a good, providing person.

I do think (no, know, I'm a physicist) the numbers from the post that landed wrong are correct.

But in the end the point is to "feel" comfortable. If this set up makes that so for you, then goal achieved.

 

The post about the thermal mass heat math?
I have no doubt it is correct.
I took it that way.
I'm not fooled into thinking that I have created some amazing rocket stove.
When I build a house in the 10acres we own it will be built well insulated and it will have real thermal mass.
The 1k or so lbs does help though.
I know insulating would help more than the thermal mass.
The insulating will come as we get more remodeling done.
Im never gonna argue that 60f is more comfortable than the few times a year we get down to 40. I sure wish it was 60f all the time.
40 really ain't that bad though. It's not like it lasts all day and upstairs is always warmer.
We've had a few times over the years (not this year) where I have told wife and kids to spend the night at Grandma and Grandpa's (one time in our 2nd year I couldn't get house above 34)
I just think it's funny when certain people question my manhood and think I'm a tyrant holding my wife and kids hostage in horrible conditions.
We as a species ( definitely including myself) have become horribly soft and spoiled.
Part of my goals in raising my children is to raise them tough, with a I can survive type mindset. It's not like I purposely keep the house at 40, but when it is we still live our daily life's the same just have jackets on
Wether people agree with that or not is of no difference to me.
It's funny some people set their a/c to 60f in the summer, but apparently on a woodstove forum 60 is borderline to cold for winter?
Don't make sense to me

 

Lol, I agree. In TN (where I lived before here), my wife brought a blanket to the cinema in summer because it was colder in there than in winter
Doesn't make sense indeed

 

I wanted to articulate your last paragraph but wasn't sure how.
I think that exactly is why we see a 5f difference from our 1k lbs of mass.
If my stt are 700 to 800 during peak burn, sure that's pumping a bunch of heat into the room, but it dissipates fast because of our not so good insulation.
If I pump that 700 to 800 into stones that get between 300 and 500 it doesn't give us as high of a temp,but it retains it longer and gives us higher average temps instead of shorter bursts of high air temps

 

Higher room temps do lead to a larger stream of BTUs to the outside per hour (because proportional to the temperature difference).
But a bit lower room temp for longer leads to a lower BTU per hour loss (lower temp difference) , but does so for longer.

So the total BTU loss will be the same, just with a different time profile leading to a different room temp profile

(Basically I'm saying that the exact total BTU loss will always be exactly the same - 100%, regardless of installation parameters.)