okay got a good one for you. the mud job for my IS has been poured and it's curing a week, it's 1.5", getting another 3/8" bed on top of that to receive bricks. 42" x 49" with 70 bricks on top you will have a 700 pound mass of hearth pad. on top of that the IS is 175# heavier than the jotul 500 it replaces so mass in the area has been significantly increased. here's the question. when the stove goes out, how long will that radiated on mass keep my 900 square foot house warm. my guess is 2 hours. if you have the typical 400# wood stove and it goes out, the stove metal's heat will keep things warm a couple of hours. i would guess the pad about the same and the net effect, IS plus pad to be 4 hours between the both. they have done astounding things with passive solar heating masonry and water columns and gotten 24 hour results. this here little thing i am doing has to be good for something. someone here is going to know something based on the construction process and living with the result. the funny thing is i was originally planning to use durock for its insulative value until i woke up. every 1/2" of mortar gets you .1 R so there are different ways to get to the same result. the one i chose yields more beef and of course a level pad to lay brick on. i had some galvanized mesh around and the net cost of the pad was $100.
I seriously doubt you'll get much radiant heat from the hearth after the stove goes out. Not enough to notice at least. Ours seems to get quite warm but the soapstone stove stays much warmer and for a much longer period of time. But even with that, a 150-200 degree stove really does not throw much heat. Even 24 hours later our stove might be 100 degrees but that is not enough to notice. Shoot, the hot water from the tap is warmer than that.
well here's the thing. if i had a solar heated floor slab it wouldn't get very hot at all, just a small increment above the home temperature. the slab would still carry the house a number of hours after the sun goes down. 700# of masonry heated an extra 10 or 20 degrees has to count for some amount of heating time until it normalizes with house temperature. it stands to reason the house will gain some extra period of heat and it's only a matter of for how long. it's not going to be the radiant heat experience we are addicted to with metal stoves. more of a thermal sink really. according to jotul the 1/4" slate tile in the foyer that was under the 500, this is one quarter slate thinset over plywood, is adequate for spark and otherwise protection. it's funny the IS requires the .41 R hearth pad in relation to that. no complaints on that score you have to be way ahead of an insurance requirement, and the added benefit of the extra thermal mass. the question could be addressed more scientifically by taking temperature readings at various points of the hearth pad as the stove is going out, averaging them, and then seeing how long it took for the brick to cool to house temperature, or maybe a predetermined 72 or 75 degrees. of course it's easier to let the stove go out in both cold and shoulder weather, and seeing how long the house holds up. all that mass has to count for something. summer solstice and all we are keenly aware the heating season is just around the corner. this question gets answered in the fall and you guys will get a report. small details as this and the little balances we work out in life are an intense fascination with me.
I'll be watching this thread as well. Like Backwoods said, I doubt the temperature difference between the air in the room and the thermal mass of the hearth will be significant after a long burn, but any added heat storage that can radiate into the stove room is probably a good thing. As for the water columns, water's specific heat is awesome... The only time I've noticed this is in large masonry fireplaces that have been burning hot for a long time and then quickly go out. I'm curious as to what your data will show, though. Good luck!
cripes. that was the easiest and most intuitive,, let alone successful pic i have put on a forum. okay. this is chucker's foyer, aforementioned brick hearth pad- the wife and i worked out the pattern- IS stove which i figure will be handy to burn wood in, in tasteful and easy on the eyes charcoal/moss green, floor to ceiling wood rack adjacent to front door. this is as good a life is going to get at least for folks like us. i have hopes for this hearth pad. small effects and nitpicking are the soul of good work in the trades. between the heavy stove and the hearth pad this is about all you would wish to plop on 4 2x10 floor joists otherwise the hearth pad could have been taller. were it more massive it would retain more heat, however, i figure things are on a 24 hour cycle and you need something compact enough to just come to heat during one long burn. hopefully you do the burn, maybe 14 hours, the stove and pad hold up some amount of time beyond that, and the mass of the building adds time until the stove needs to be rekindled. this is conjecture at this point. i am thinking that in transition weather the stove might need to be lit once a day. with an efficient stove and an efficient building hopefully you can expand the amount of transition weather and shorten the all day burn weather.
Love the simple configuration of your IS. When I first saw the customization options of the IS, I thought to myself "who wants that?". Well, clearly I was wrong as it appears 99% love the customization. I guess I am in the 1% that like the "stock" configuration which I assume is what you have. With no andirons, is your plan is to load N/S? Do you have any of the soapstone panels on the sides? You know, one picture really isn't enough for most of us here.
the simple look is good for me. the really important part of that is the stove top and not having the gear or other appliques on the front. i plan to do a lot of cooking on the stove as well as heating hot water bed warmers &c. and the smooth top is flexible for any shape you put on. i was thinking N/S loading would be easiest. is this so? i didn't order soapstone panels. what do they weigh, and are they advisable, they can be done later. will load some more pix later.
I would think you could add the side soapstone later. As you can order Xtra ones my guess they weigh about 100 pounds and would give you more radiant heat than the hearth wood. I mean that's why people make soapstone woodstoves. I assume you got the soapstone inside. I really think I am gonna so like that better than firebrick..
I have a lot more than 700 pounds of exposed bricks in my exposed hearth and chimney in my den that my stove insert sits in. Sure it may stay well over 100 for hours but as that stove cools even as it burns it cools down as well. My 700# steel stove may still be 200 after it goes out mostly and all that brick mass warm but it surely is not putting any noticeable heat into the 450sqft room. I am like backwoods. Sink think it will make much difference of it weighed 300 or 700#. My brick chimney mantel area is 6 foot wide and goes to the 8ft ceiling as exposed brick.
