Anyone add mass around their hearth specifically to enhance heat retention & radiation?

[joefrompa]

Hi all,

I'm thinking about how I want to prepare my home for maximum heating. Obviously things like air-sealing and insulating are big, but I have one other idea I thought I'd share with the forum:

My Lopi Republic 1750 insert is going to be put into a narrow, long room (approximately 10 feet wide by 40 feet long, of which 20 feet is the kitchen area). Directly in front of the fireplace is our sofa and TV, and our favorite spot in the house.

We have a nice ceiling fan and other fans that will help circulate heat, but I thought this might be a great candidate for dropping in some real heat-sink mass to help stabilize temperature and provide a nice smooth temperature curve afterwards.

Now, I have no idea how much real mass it would take to create any notable effect, but I've thought about adding several hundred pounds of stone to the hearth area to absorb heat and then give it off slowly after the fire cools down.

Has anyone ever done this? Anything to report if so?

Joe

 

[spirilis]

Theoretically the best material to add is water, as water gives you the most thermal storage per mass, but I dunno how to pull that one off. A sealed tank of water with brick veneer built and mortared around it as a table/island would be interesting.

 

[branchburner]

For thermal storage in the same room as the stove, but not on the hearth: water + dirt + pottery = large potted plants.

Other tips for thermal mass include purchasing old furniture from Fred and Barney after Wilma and Betty have redecorated. Extra cushions recommended.

 

[Backwoods Savage]

Good luck on that Joe. From what I've found it is not practical to attempt too much. We put a lot of stone (soapstone) around our stove. lol It works great too!

 

[vvvv]

spread the heat, house is full of mass. if u build a hot area, the ceiling will accelerate the heatloss

 

[joefrompa]

Hmmm...I like the idea of keeping something like 50 gallons of water nearby....for obvious fire reasons + heat retention. Now how to convince my wife that that 55 gallon drum looks attractive. Maybe we'll aim for a modern industrial look

 

[stoveguy2esw]

one of the functions or anderons in an open fireplace was heat retention though it wasnt all that effective due to size and shape. the idea is to have enough material to absorb and slowly release that heat but remember the more heat that is absorbed during its release from the stove the less that will initialy circulate through the house

 

[madison]

.....remember the more heat that is absorbed during its release from the stove the less that will initialy circulate through the house.....

Well put, and you will not face the wrath of your wife with a smelly fifty gallon drum of water sitting next to the stove.

We have fairly think ( ~ 6") dolimitic limestone and granite on the walls around and behind the stove - for looks only, and blue stone for the hearth (see link below) and, maybe it is because of the way the T6 convects heat vs radiating heat, but the stone gets maybe a few degrees warmer than the air temp. and quite honestly, does not really do anything like what you are expecting in your original post as far as noticibly radiating heat. first thing in the morning when the stove has cool off a bit I'll put my hand on the wall at it may feel a tad warmer, but only if you put your hand on it.

Now possibly a steel stove that radiates a lot of its energy would be a different story, but I have my doubts as it would heat the air and interior walls of the house just like the 50 gallon drum of water....

Is Albert Einstein available for a consult?

 

[oconnor]

When we reno'd our fireplace, we ended up using cement to reface the older broken brick, and used a concrete slab as a mantle. This was all in direct contact with the fireplace and chimney, as opposed to it all being hidden behind plaster and lathe.

The other thought I've had was to expose the chimney in the upstairs floor. Because I insulated the liner, it is rated at zero inches to combustibles, so no need to shield it. That would be my plan if I was to ever build new - expose as much of the masonry as can be done.

 

[btuser]

Drywall works too, and its pretty much hidden if you don't want that barrel in the middle of the room. Double up some 5/8 fire-rated sheetrock on the sides and ceiling. you'd lose about 3" on the sides and less than two inches on the ceiling. It has a higher specific heat than most stone, because of the water in the drywall.

 

[mtcates]

I didn't specifically add this mass but never the less I have it. All 20,000 pounds of it. It really moderates the heat of the stove but if it does get cold in here it takes a long time to heat it all back up.

 

[Todd]

If you were burning a radiant hearth stove I'd say yeah, a little extra mass will help, but you are burning a convection insert and the radiant heat is mostly blocked by the built in shroud. You will get radiant heat off the front glass so maybe a thick hearth in front would help retain some heat but I doubt you would notice much.

 

[Needshave]

We are looking into different types of wood heating systems for a home we plan on building. A masonary heater is what we're looking into for the thermal mass effect.

 

[Battenkiller]

I did the opposite. I put the stove by the thermal mass.

4000 pounds of cement block plus the inner chimney brick and clay flue tile holds its heat for a very long time after the stove is cool. Note the sheet metal as well. There's a few hundred pounds of it back there. Stoveguy is right, though. It really robs you of a lot of useful heat while it's ramping up to temp. Thankfully, that is accomplished as the outside temps are ramping down at the beginning of the season.

In basement installs, there are many things you can do because you don't give a crap what it looks like. ;-)

 

[Todd]

We are looking into different types of wood heating systems for a home we plan on building. A masonary heater is what we're looking into for the thermal mass effect.

There ya go, if I was building a new house I'd build a huge masonry heater smack dab in the middle.

 

[BrotherBart]

Same setup as my house. Let the blower in the insert shoot the heat across the room and find the stairwell. Leave the blower on low till bedtime and then crank it up when you go to bed.

 

[vvvv]

We are looking into different types of wood heating systems for a home we plan on building. A masonary heater is what we're looking into for the thermal mass effect.

There ya go, if I was building a new house I'd build a huge masonry heater smack dab in the middle.

masonry is a poor insulator/good conductor. best to terminate the masonry below the ceiling & finish with class a flue with a damper added.

 

[vvvv]

We are looking into different types of wood heating systems for a home we plan on building. A masonary heater is what we're looking into for the thermal mass effect.

There ya go, if I was building a new house I'd build a huge masonry heater smack dab in the middle.

masonry is a poor insulator/good conductor. best to terminate the masonry below the ceiling & finish with class a flue with a damper added http://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html#c1 water holds 5x as much heat/lb as granite

 

[firefighterjake]

When we reno'd our fireplace, we ended up using cement to reface the older broken brick, and used a concrete slab as a mantle. This was all in direct contact with the fireplace and chimney, as opposed to it all being hidden behind plaster and lathe.

The other thought I've had was to expose the chimney in the upstairs floor. Because I insulated the liner, it is rated at zero inches to combustibles, so no need to shield it. That would be my plan if I was to ever build new - expose as much of the masonry as can be done.

Love the pics . . . this is you in the Dr. Dentons posing beside your handiwork, right?

On the serious side . . . a very nice looking hearth and installation.