Masonry Heaters

[photoboy74]

PB74, would you mind taking measurements of your ofen and posting them? Also, what is the approximate outside temp. of it when at its hottest?
@churchie,

the measurements are (in centimeter. sorry, but i'm in germany! the conversion to inches is 2,54 cm/inch):
height: 175
length: 96
depth: 55

i don't know what the outside temp is but i do know that around the firebox is the hottest after it has fully warmed up. even so, i can put my hand on the tile, hold it there, and not burn myself. hope that helps!!

@marty s,

that tempcast is a beauty. the only thing that i wish i could change with my berliner is that it had a window to watch the fire. do you use the baking oven and if so, is there really a difference between bread from that and a regular bake oven?

 

[Martin Strand III]

Hi Marty, fine looking heater. I have a couple of questions if you don't mind:
1) Did you construct this yourself or did you have a mason build it?
2) How did you do the transition from the masonry heater to metal flue/chimney?

Thanks;

Earl

Earl:

1) The inner core was purchased and installed by the local dealer. Some of the refractory pieces in the core weigh as much as 225 lbs. Since I dislocated my shoulder whipping a dead horse, I didn't feel I should take the job on, though many do (DIYs). Over the core, there is a layer or cardboard (yup, which later burns off leaving an airspace) then a layer of brick. Some stop here. I wanted the tile look, so it went over the brick. The facade (brick and tile) was done by a local mason and can be just about any natural stone/brick/tile combo you can imagine staying w/in the Mfg specs for thickness.

2) The MH chimney actually starts at floor level behind the heater. The first part has a manual damper then double wall Class A metal chimney within the structure of the heater. The black metal chimney seen is single wall (I wanted heat!). The 2nd smaller chimney in the pic is from a basement wood/coal stove. Main floor and roof penetrations go back to double wall Class A metal chimney for code requirements.

Thanks for the interest.

Aye,
Marty

 

[Martin Strand III]

(SNIP)

@marty s,

that tempcast is a beauty. the only thing that i wish i could change with my berliner is that it had a window to watch the fire. do you use the baking oven and if so, is there really a difference between bread from that and a regular bake oven?

I cook in the bake oven almost nightly during winter. I haven't made bread yet since I'm not a cake eater. The closest to bread that I have made is pizza which cooks fast and is delicious. Guess you could say I am a pie eater (pizza...).

Timing is everything in a hot MH bake oven. After the firebox fire dies down, the bake oven can be 800* F or so. That's too hot for cooking. I use a laser temperature gauge to measure the temp of the bake oven before cooking. I do pizza at about 550 - 600* F. If it cools down too much after a fire, a fire in the bake oven will bring it back quickly. Sometimes I need to do this if I spend too much time on my rocking horse.

Thanks for the interest.

Aye,
Marty

 

[killick]

Thanks Marty, much appreciated. My friends vents into an existing masonry chimney but I have seen them with a transition flange connected to the heater which allows the use of a regular metal flue or insulated chimney. The tile, along with looking great, adds some additional mass for heat storage.

Earl

 

[Battenkiller]

I have a friend who has what he calls a "Russian fireplace" that he heats up once a day for about two hours as hot as he can get it, then let's it die out. It has like 9000 pounds of soapstone in it and cost him a fortune, but his house rarely changes more than a few degrees throughout the day.

I get a similar effect with my basement install of a traditional cast iron stove. It heats up several thousand pounds of cement block and masonry chimney. After about a week of steady and heavy burning, the mass of masonry gets to a point where the house will only drop a few degrees even after the stove gets cold (rarely).

I took some IR readings of the wall in my kitchen that is adjacent to the chimney. It is well over 100ºF. That might not seem like much heat, but it's like having a gigantic low temp stove between my living room and kitchen.

This has been highly effective in keeping us from the temptation of turning on the electric heaters for almost twenty years now. Of course, the basement is fully insulated. Otherwise, I would lose most of this heat to the cold basement walls.

 

[Martin Strand III]

I have a friend who has what he calls a "Russian fireplace" that he heats up once a day for about two hours as hot as he can get it, then let's it die out. It has like 9000 pounds of soapstone in it and cost him a fortune, but his house rarely changes more than a few degrees throughout the day.

I get a similar effect with my basement install of a traditional cast iron stove. It heats up several thousand pounds of cement block and masonry chimney. After about a week of steady and heavy burning, the mass of masonry gets to a point where the house will only drop a few degrees even after the stove gets cold (rarely). (SNIP)

Get the low down on the different (Russian, Swedish, Finnish, Danish, etc) masonry heaters here:

http://www.firecrest-fireplaces.com Click on Heating Solutions.

Now, as you see, they all use the same principle our ancestors used thousands of years ago: fire heats rock, rock stays warm after fire is out which heats man and cave. Big cave? Use more rock. Smaller cave? Use less rock.

The difference in more modern models of rock (basic models hundreds of years old) is in the exhaust smoke/heat channels which help absorb heat from the fire.

You use a slightly different set up but use the same principle as your ancient ancestors. Congratulations and enjoy!

Aye,
Marty

 

[sgcsalsero]

..for some reason the link isn't picking up "Solutions" but it works if manually copied and pasted.

Thanks

 

[Battenkiller]

Now, as you see, they all use the same principle our ancestors used thousands of years ago: fire heats rock, rock stays warm after fire is out which heats man and cave. Big cave? Use more rock. Smaller cave? Use less rock.


You use a slightly different set up but use the same principle as your ancient ancestors. Congratulations and enjoy!

I guess it's fitting that the stove is in my "man cave".

My cave woman OTOH wishes I could get just a little more of that good heat upstairs. 67ºF is about all I can get it to in the living room when it's really cold outside. The answer would be to run my flue temps higher than I already do to warm up the chimney even more, but then the stove flirts with the serious overfire range and downstairs in the wood shop is not livable with 90º plus temps.

I think the ultimate answer is a smaller stove in the basement and a pellet stove insert in the living room fireplace. Since the two flues are enclosed by the same masonry work, I'd get a more even and steady heat than I already do.

 

[Martin Strand III]

(SNIP) My cave woman OTOH wishes I could get just a little more of that good heat upstairs. (SNIP)

Before investing in extra stoves, try this as I've done it successfully in my home. Caviat: You must have an open door at the top of the stairwell and a little fan.

Put a small fan on the floor in the door space of the main floor blowing down the staircase. This helps Mother Nature rid the main floor cool air on the floor which naturally will go downstairs but now is helped with your fan. Forcing cool main floor air downstairs will displace warm ceiling air from the basement upstairs where she wants it.

You may get an unexpected reward!

Aye,
Marty

 

[awoodman]

Another type of masonry or thermal mass heater.
https://www.hearth.com/econtent/index.php/forums/viewthread/42827/

 

[spirilis]

Another type of masonry or thermal mass heater.
https://www.hearth.com/econtent/index.php/forums/viewforum/2/P105/

? link takes me to the forum but no thread

 

[awoodman]

it's like having a little sun in the room. after working outdoors in the winter or taking a shower, my wife and i like to stand against our "berliner." even though it has an extremely large amount of heat stored inside, the outside is never to hot to touch. it is amazing.

With a Rocket Stove Mass Heater you can heat up a bench type thermal mass to lay on.

 

[karri0n]

Take a look at http://mainewoodheat.com for some of the most beautiful(and expensive) masonry heater setups I've ever seen. many of them have fairly large write-ups and galleries on their construction and use.

 

[GregGavish]

Since it's not the typical pellet stove, my cousin hired a designer and masonry in MD to team up for the project. They have managed to produce an outstanding job. The stove actually became a main feature in the living area of the house.

 

[slindo]

I am fascinated with Masonry heaters, but in much the same way I am fascinated by dowsing and Fish carburettors. I almost built one a few years ago, but chickened out.

There were a few things that bothered us about masonry heaters. The big one is that you have to make a couple fires from scratch each day. I hate making fires. My cat VC burns for weeks on one fire. It's much easier for me to throw in a couple logs to keep it going through a warmish day, than find more kindling in late winter to restart it when the sun goes down. Another thing is that while enthusiasts like to claim they will heat for 12 to 24 hours on one fire, you aren't really getting any useful heat out of it for the first 4 to 6 hours after the burn - the old saying is, tonight's fire is tomorrow's heat. So you really got to have a conventional stove, or backup heating, as well as the masonry heater, for those times when you are just plain COLD and need some heat NOW not in 6 hours, or want to cook or heat some water when the power is off.

Also, I could never get a good handle on just how efficient they really are. A friend who is about to build one boasts how it will heat their rambling house on "two armloads of wood a day" instead of the 6 or 7 they have to haul with their current Jotel - and that much only in the coldest weather! Their big worry is it will put out too much heat. Many masonry heater sites echo similar claims, but with no independant authentication of the claims. The best scientific tests I have been able to find show masonry heaters in real life operating at 80 to 86% efficient. That compares to 75 to 85% for a good woodstove, Another test says that a house a bit smaller than ours would still burn about 3 cords a winter with a masonry heater (we burn 4 with an iron stove). That would suggest a masonry heater might eliminate one load out of 8 or 9, still a long shot from just two little armfuls a day.

One last point to consider. To get the most out of a masonry heater, you should be using it as a radiant heater, which means you really should have an open plan house, designed around the heater, so as to maximize use of radiant heat. If you think you are going to stick it in a corner of an old farm house, or in a mudroom along with the wood, you are not going to be happy with it.

That said, I remain fascinated by them. If we were the sort of people who were home all day, cooking and baking, I think we could be very happy with one.

 

[Martin Strand III]

(SNIP)

There were a few things that bothered us about masonry heaters. The big one is that you have to make a couple fires from scratch each day. (SNIP) Another thing is that while enthusiasts like to claim they will heat for 12 to 24 hours on one fire, you aren't really getting any useful heat out of it for the first 4 to 6 hours after the burn - the old saying is, tonight's fire is tomorrow's heat. So you really got to have a conventional stove, or backup heating, as well as the masonry heater, for those times when you are just plain COLD and need some heat NOW not in 6 hours, or want to cook or heat some water when the power is off.

Also, I could never get a good handle on just how efficient they really are. (SNIP) Many masonry heater sites echo similar claims, but with no independant authentication of the claims. The best scientific tests I have been able to find show masonry heaters in real life operating at 80 to 86% efficient. That compares to 75 to 85% for a good woodstove, Another test says that a house a bit smaller than ours would still burn about 3 cords a winter with a masonry heater (we burn 4 with an iron stove). That would suggest a masonry heater might eliminate one load out of 8 or 9, still a long shot from just two little armfuls a day.

One last point to consider. To get the most out of a masonry heater, you should be using it as a radiant heater, which means you really should have an open plan house, designed around the heater, so as to maximize use of radiant heat. If you think you are going to stick it in a corner of an old farm house, or in a mudroom along with the wood, you are not going to be happy with it.

(SNIP)

My input re your remarks. I am in my 6th heating season with a TempCast masonry heater.

"A couple fires from scratch each day" is a benefit, not a detriment. Consider the firebox and heater is already hot from the previous fire. If your design is ample, the wood will be close at hand. Stacking and reigniting dry wood is a snap taking only a couple minutes. Oh. 2 fires/day works well unless the outside temp drops below zero - then 3 fires. My firebox "full" takes about 50 lbs of dry fire wood for one fire which produces some 250,000 BTU's of radiant heat which a metal stove can't take or do.

Not getting useful heat until 4 - 6 hours after the burn is simply wrong. Even the first fire of the season with a room temperature unit will emit almost immediate serious radiant heat through the glass door(s). So much it can burn your short ones if you stand too close... Again, if you designed it right, it will provide continuous hot water ("T'd" to you H/W system) when you're out of gas or electric for your H/W heater.

There is more that goes into "efficiency" than I want to get into here but suffice it to say the only unit that burns cleaner is a pellet stove. The problem with metal wood stoves is that they are designed to burn wood inefficiently (low combustion efficiency by turning down incoming air to not over fire the stove) and they have a high heat transfer efficiency (metal conducts heat to the room very rapidly). A masonry heater is designed to have a high combustion efficiency (burns wood with maximal incoming air to get very high firebox temperature) and moderate heat transfer energy to release heat slowly (read comfortably) to the room.

Having had several wood stoves, a fireplace insert in my life plus a gas stove, I feel I am qualified to say a masonry heater burns 1/4 - 1/3 LESS firewood than a good sized metal wood stove. This pretty much jives with what the Mfgs claim.

You are correct that an open floor plan is best for radiant heating and no one should be happy with sticking ANY heating stove in a corner or outside wall. These units perform best when the entire chimney is contained in the envelope of the home.

That's my story and I'm sticking to it.

Aye,
Marty

 

[killick]

I would agree with Marty's assesment on the use and operation of a masonry heater.Marty,I am interested in how you plumbed in your water line.I am assuming it picks up heat from the baffles and is not installed in the fire box?

Earl

 

[Martin Strand III]

I would agree with Marty's assesment on the use and operation of a masonry heater.Marty,I am interested in how you plumbed in your water line.I am assuming it picks up heat from the baffles and is not installed in the fire box?

Earl

Earl:

I did not plumb my MH unit with hot water coils T'ing into my H/W supply. Reason: too much $$$ after the MH. And, I'm not worried about hot water. In fact, I find it easily...

Those who do plumb their MH for H/W do so not in the firebox WAY too hot. The coils are place in a back or side wall and the finish facade placed over the coils. The walls and sides get to 170* F or so which is adequate.

Aye,
Marty

 

[killick]

Whoops! Misunderstood your post above. Definitely do not plumb into the firebox..

Earl

 

[mainemac]

Marty


Like many others I find the idea of a Masonry Heater intriguing.
I love the look and the efficiency of it all.

How does the firebox viewing aesthetic go? She who must be obeyed (my dear wife) was saying that she loves our woodstove insert in part due to seeing the fire roiling along a few times a day

I myself would not mind having 5-6 reloads daily but see her point 100%

With 2 small short fires a day do you miss the 'ambience factor'?

Tom

 

[Martin Strand III]

(SNIP)

How does the firebox viewing aesthetic go? (SNIP)
With 2 small short fires a day do you miss the 'ambience factor'?

Tom

It seems you do not understand, or have never seen, what a masonry heater fire (about a 250,000 BTU event) is all aboout. Don't feel bad. You're not alone. Let me clarify. Not "small". Not really "short". Exceptional ambiance. Not at all comparable to a choked down air deprived wood fire in a metal stove.

Firing up 50 lbs of wood in the firebox of the TempCast with wide open air intake produces a spectacular viewing event for about 2 hours through the door glass in the firebox. The flames then pass through a slit in the bake oven floor, visible here through the bake oven glass as 'blast furnace' with the flames violently hitting the ceramic roof (the violent flame path is designed for high secondary combustion efficiency) of the bake oven before being redirected up, out and downward into the ceramic heat exchange channels (flames being invisible here some 15' or so before entering the chimney). The masonry, about 3 - 4 tons of it (yup) from the firebox to the chimney, absorbs the intense combustion heat at about 1800* F or so in the firebox allowing only about 275* - 300* F out the chimney. This absorbed heat is then gently released as radiant heat to the room over the next 20 hours or so.

Having a fire like this with morning coffee and then again (maybe 3 fires/24 hours when it's single figures outside, maybe a dozen/year) with a sundowner provides total ambience for us since wife and I rarely are here most of the day. More than 3 fires would serve no purpose.

Get the picture?

Aye,
Marty

 

[sgcsalsero]

Hi Marty, we all owe you a big thanks for patiently responding. I think there are a couple folks who have a masonry heater who find hearth and then quickly figure out they are in small company and don't hang out. Because you've had your share of stoves and understand 'the physics' of different products makes it even more pertinent. .02, maybe you should make 'the basics of masonry heaters' youtube and then point folks there from time to time.

Off topic point on cost: My co-worker just bought a Cadillac CTS - something he's wanted for five years. My grandfather had a $10k 25' Macgregor sailboat. A house I bike past has a ginormous masonry fireplace that has to be 15' or more tall - from my observation probably used less than 30 times per year (in the two years I've biked past it it's never been used). I just so happen to want a masonry heater a lot more than a Cadillac, sailboat, or huge patio with outside fireplace. So when I get the opportunity someday, that's what I'm doing. Maybe the kids will be grown and gone - right about the time my bones will need the extra warmth for the winter. The 'cost discussion' is all about what people consider a priority in their lives. If they want something bad enough, a lot of them do find a way to get it.

 

[Martin Strand III]

Hi Marty, we all owe you a big thanks for patiently responding. I think there are a couple folks who have a masonry heater who find hearth and then quickly figure out they are in small company and don't hang out. Because you've had your share of stoves and understand 'the physics' of different products makes it even pertinent. .02, maybe you should make 'the basics of masonry heaters' youtube and then point folks there from time to time.

Off topic point on cost: My co-worker just bought a Cadillac CTS - something he's wanted for five years. My grandfather had a $10k 25' sailboat. A house I bike past has a ginormous masonry fireplace that has to be 15' or more tall - from my observation probably used less than 30 times per year (in the two years I've biked past it it's never been used). I just so happen to want a masonry heater a lot more than a Cadillac, sailboat, or huge patio with outside fireplace. So when I get the opportunity someday, that's what I'm doing. Maybe the kids will be grown and gone - right about the time my bones will need the extra warmth for the winter. The 'cost discussion' is all about what people consider a priority in their lives. If they want something bad enough, a lot of them do find a way to get it.

I've had that 'cost' thing tossed at me before. Believe me, it's all relative (see below previously prepared). Keep reading.

Costs (of ‘expensive’ $25K masonry heater) are relative.  And, it’s for essential home heat. 

SAVINGS/PAYBACK CALCULATIONS (‘Tight’ new 2900 SF main & loft home)

Nov ‘04 - Oct ‘08 (48 months)
With Masonry Heater/Harman TLC 2000
$2876. (1278 G) LPG Purchases, actual @ $2.25/G ave
(stove, H/W, Onan 12K generator)
$ 300. Cordwood Purchases
(Rotator cuff inj shoulder 3/05)
$ 250. Anthracite Purchases (basement stove)
$ 65. Chainsaw/tractor fuel
__________
$3491. /48 months = $ 73./month

Without Heater/Stove - Est Expenses
$7200. LPG ($300/mo x 48 mo/2)

$7200. LPG cost 4 years w/o add’l heaters
- 2876. LPG cost 4 years w/ add’l heaters
_______
$4324. Saved in 4 years

BUT, I burn my own wood, so
$3200. Saved from not buying most firewood
(4 cords/yr @ $200/cord x 4 years)
$1881. Average saved per year

$25K/$1881. = Payback is 13.3years (worse case) without adding up non-essential expenses or using current LPG costs (below).

For just 1 year, add up what you spend on non-essentials such as:

$25000. Your second or third vehicle (I have one)
$3000 - ? Your boat (I had three and I admit it’s a weakness, sorry)
$15000 Swimming pool for your house
$125000 Your “hunting cabin” or second home (I have one home)
$1500 Tobacco $5/pk x 300/yr (a vice that’s not nice)
$3600 Ethanol $10/day (wine, beer, booze)
$50000 - ? Your mistress (Been thar, done that - a real waste)
$2500 Eating at restaurants (I do this modestly)
$3500 Hunting and fishing trips (I quit killin’ things long ago)
$1000 Blown pocket money, ATM w/drawls (Everyone does this)
? “Stuff” you bought but haven’t used in at least a year
(It adds up)
$$Big Bucks A divorce or two (see a few lines up;no comment)
Yada, Yada, Yada

and the cost, ease, safety, effectiveness, eco-friendlyness and convenience of a big hot rock (aka masonry heater) in your home doesn’t seem so out of the question.

Other testimonials:

1. “Today, many people think nothing of spending tens of thousands of dollars for an automobile that holds its value for a very short time.  But the investment in a masonry stove is truly rock solid.  As part of a home remodeling project or new home construction, masonry stoves easily pay for themselves -  in reduced heating costs, increased comfort, and added value to the home.”

http://www.fnaturalhomes.com/fountainheat.htm


2. "There is one other important if not vital thing to consider with all of the talk of money and payback. Marty, or anyone else with a masonry heater, is making a fractionally larger long-term payment, (added pro-rata principal and interest due to masonry heater), in return for receiving short-term benefits, such as decreased wood consumpton, a cleaner chimney, few needed replacement parts and a safe comfortable heat source which doesn’t need much tending so it’s a nice thing to have now. But if the world went to crap it would be great to have since you can get heat, cooking, and hot water with few moving parts. So it’s not only an investment, it’s also a hedge against risk.

A payment in return for decreased risk and more certainty with regard to return on investment is called insurance And if one takes a look at it that way then these look even better as ‘investments’."
--Commercial Real Estate Insurance Person

Aye,
Marty

 

[Todd]

Do masonry heaters have a damper you need to close after that 2 hour firing to keep the heat in?

 

[Martin Strand III]

Do masonry heaters have a damper you need to close after that 2 hour firing to keep the heat in?

Yes.

Aye,
Marty