Question about heat shield

Northern Flame

New Member
Aug 25, 2020
6
PA
Hey Guys,

Okay...I think I have narrowed my search down to the Jotul F45 Greenville. I am going to be putting it into my (now) non-functioning fireplace. My question is...the heat shield on the back takes up space that would make it fitting much less snug. Do i need it if it's sitting in my fireplace? The firebox is brick and the outside part fire place is stone. If I could take that off it would make it a lot easier but I don't want mess up the stove.

Any helpor insight you can give me would be helpful! Thanks!

p.s. - I'm new and I love this site! :)
 

snaple4

Feeling the Heat
Dec 18, 2017
265
AR
You could take it off but I haven’t looked at that unit to see if removal voids warranty. The first thing that popped into my head was you don’t have enough room for the stove in the first place. What are specs of fireplace?

edit: what’s between the brick and stone? Wood, concrete, metal, fiberglass, bones...?
 
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Northern Flame

New Member
Aug 25, 2020
6
PA
You could take it off but I haven’t looked at that unit to see if removal voids warranty. The first thing that popped into my head was you don’t have enough room for the stove in the first place. What are specs of fireplace?

edit: what’s between the brick and stone? Wood, concrete, metal, fiberglass, bones...?
It has walls that run on a diagonal, so the mouth of it is wide in the 30's...35, 36 inches something like that. The back wall width is 22 inches and the top of the mouth is 28 inches and change. maybe 1/4, or 1/2.
There is a bit of cement on the floor outside the fireplace that is about another foot. From the end of that all the way to the back on the fireplace is 33, 34 inches.

So, i was going to get the short leg kit to help with height. But that heat shield pushes it out almost all the way to the edge of the cement pad outside the fireplace.

I think it's just some sort of cement sticking it all together. The house (and probably the fireplace) was built in 1947.
 

kennyp2339

Minister of Fire
Feb 16, 2014
5,122
07462
While there is nothing wrong with sticking a free standing stove into a fireplace hole, you are sacrificing performance / heating capability of the unit, free standing stoves are more suited for free standing outside of any enclosure since they are both radiant and convective.
An insert is more suited because its essentially a woodstove that is wrapped in an exterior metal jacket to make it more convective in nature.
Either way, build a block off plate out of sheet metal, throw some fire proof insulation on top of the sheet metal, also run an insulated liner, dont forget the stainless steel appliance adapter to connect the stove to the liner.
You may also need to build a hearth extension, you will need 16" minimum in front of the stove door, since your going with a short leg kit, you may need to call the manufacturer to confirm ember only protection in front of the stove or if the hearth extension needs to have some K factor to it.
 
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coaly

Fisher Moderator
Staff member
Dec 22, 2007
3,930
NE PA
Lots of reasons why you don’t want to do this.

First, this is a radiant heating stove. Heat radiates in all directions. Hot air rises. Heating capacity or BTU goes by the temperature of each square inch of surface area. You are removing all that square inch surface area of the equation, allowing it to be absorbed into the masonry, instead of heating the house. It’s nice to think of heating the brick and stone mass to radiate the heat into the home, but in actuality, the heat loss to the outside and rising upward out the roof is more heat loss than what moves into the building. (Unless the entire hearth is indoors and extreme high radiating more into the building)

Stoves heat with 2 types of heat. Radiant, as I explained above and Convection. (as explained in the post above) A fireplace Insert has an air chamber around the firebox to move convected hot air out of the firebox with a blower. This hot air is blown into the home making it much more efficient. You want to extract the heat bringing it into the home. The blower will pull cooler air from near the bottom front off the floor around the firebox, and expel it at the top. A stove in an alcove or fireplace opening needs airflow to do that.

Lastly, damage to the stove. Fisher was made of 1/4 inch steel plate, fully welded with a lifetime warranty. Not many are that thick anymore. One of the very few warranty claims was cracking or warping of rear or side sheets when installed in such a manner. As stated above, heat needs to radiate in all directions from the firebox. This also needs to be even. When the back of a stove has little to no airflow, it stays hot in the back, and cools rapidly in the front where it can radiate outward. This temperature differential does not allow even expansion and contraction, breaks welds, cracks or warps sheets. Very bad idea to stress the sheets unequally.

Another reason you have unequal expansion is when a stove is designed with cast iron AND steel plate. The major benefit of cast iron is its ability to move heat. That’s why pans are made of it, and the reason it is difficult to weld. Extreme heat from welding moves away from the weld area so fast, the uneven cooling cracks the iron at, or next to the weld. You have to put the entire piece in an oven or heat with torches, pack in sand as it cools to retain heat and slow cooling. This shows how much heat is removed from the front compared to the back of your stove. You’re making matters worse restricting air flow, and no way should the stove be warranted in an installation of such. It wasn’t designed or tested for that, and you should ask the manufacturer to find if they agree with this.

Also I believe the latest version of NFPA 211 now calls for 18 inches floor protection all around which includes yours in front. If you don’t have that, it’s called a hearth extension to satisfy that requirement.
 

Northern Flame

New Member
Aug 25, 2020
6
PA
Lots of reasons why you don’t want to do this.

First, this is a radiant heating stove. Heat radiates in all directions. Hot air rises. Heating capacity or BTU goes by the temperature of each square inch of surface area. You are removing all that square inch surface area of the equation, allowing it to be absorbed into the masonry, instead of heating the house. It’s nice to think of heating the brick and stone mass to radiate the heat into the home, but in actuality, the heat loss to the outside and rising upward out the roof is more heat loss than what moves into the building. (Unless the entire hearth is indoors and extreme high radiating more into the building)

Stoves heat with 2 types of heat. Radiant, as I explained above and Convection. (as explained in the post above) A fireplace Insert has an air chamber around the firebox to move convected hot air out of the firebox with a blower. This hot air is blown into the home making it much more efficient. You want to extract the heat bringing it into the home. The blower will pull cooler air from near the bottom front off the floor around the firebox, and expel it at the top. A stove in an alcove or fireplace opening needs airflow to do that.

Lastly, damage to the stove. Fisher was made of 1/4 inch steel plate, fully welded with a lifetime warranty. Not many are that thick anymore. One of the very few warranty claims was cracking or warping of rear or side sheets when installed in such a manner. As stated above, heat needs to radiate in all directions from the firebox. This also needs to be even. When the back of a stove has little to no airflow, it stays hot in the back, and cools rapidly in the front where it can radiate outward. This temperature differential does not allow even expansion and contraction, breaks welds, cracks or warps sheets. Very bad idea to stress the sheets unequally.

Another reason you have unequal expansion is when a stove is designed with cast iron AND steel plate. The major benefit of cast iron is its ability to move heat. That’s why pans are made of it, and the reason it is difficult to weld. Extreme heat from welding moves away from the weld area so fast, the uneven cooling cracks the iron at, or next to the weld. You have to put the entire piece in an oven or heat with torches, pack in sand as it cools to retain heat and slow cooling. This shows how much heat is removed from the front compared to the back of your stove. You’re making matters worse restricting air flow, and no way should the stove be warranted in an installation of such. It wasn’t designed or tested for that, and you should ask the manufacturer to find if they agree with this.

Also I believe the latest version of NFPA 211 now calls for 18 inches floor protection all around which includes yours in front. If you don’t have that, it’s called a hearth extension to satisfy that requirement.
Okay, that is helpful. Is there a stove that you suggest that could work? I know that I see people putting them in hearths often. I was think also about the Alderlea 1.2 and the Castleton soapstone stove by Hearthstone.
 

begreen

Mooderator
Staff member
Nov 18, 2005
84,195
South Puget Sound, WA
The issue here is the firebox design. Stove fireboxes fall basically into a two camps. They are either biased towards depth over width or vice versa. The F45 is a deeper depth over width stove. The F602 being a more extreme example. The PE Neo series is has a shallower, width over depth firebox, (along with some Drolets, Hearthstones, etc.). A shallower, width over depth stove will project less into the room, but with some caveats. They only burn East-West and are harder to load full due to concerns of logs rolling against the glass. Personally, I prefer a stove with a squarish firebox that allows one to load either way. In this circumstance I would lean toward the F45 with a simple hearth extension.