Why the difference between R values for hearths among Jotul models?

[Planeweird]

So I'm wondering why the Nordic 100 and the Castine F400 only require non-combustible materials for the hearth with heat shields in place, while the F3 CB(and by the way, why doesn't this stove get a cool name like all the rest? What a jip!) requires an R 1.1 for it's hearth. Is there really a structural difference here or is it an oversight by jotul on updating their literature? This honestly doesn't seem right to me. It seems as though the three are basically the same stove but just sized differently.

I obviously want opinions, but would love to hear from someone that truly knows.

 

[MountainStoveGuy]

The probes they use in testing on the hearth below the stove reads higher for the models that take X r value. The probes read below a the max value for the ones that require only non combustible. Its all part of the third party listing process.

 

[Planeweird]

I pretty much figured that. I guess my main question is how is that possible or could it have been a faulty one time reading during testing? If they all have the same type construction, ash pan, and heat shield(which would seem likely) how would F3 CB, being the middle child in this scenario require more R value protection?

I'm tempted to try and contact Jotul to inquire, but I don't know how difficult it is to get in touch with them.

And has anyone experienced this difference in heat output first hand?

 

[MountainStoveGuy]

for what ever reason, the other models get hotter on the bottom then the ones that don't. The air circulation in the stove could affect that. Shorter legs can affect that. How the firebox is insulated can affect that. It is just the way it is. The testing company tests max temps down there, and make a R Value determination based on there reading. The 3cb doesnt have a cool name becasue its one of the older stoves from that manufacture. They have had the Jotul 3, Series 3, 3TDC, and 3CB. the CB means clean burn. Its the only epa rated one of the series i believe. Its possible that the casting design they used when they built the stove was different then the F100 and F400, which are fairly new models. Manufactures dont retest stoves unless they have to. It costs them a fortune. But what ever the case, the 3cb gets hotter below then the F100 and F400.

 

[Planeweird]

Well, crap MSG! You're not givin me the answers I want. Maybe if I keep asking the same question in different ways I'll get the answer I'm seeking? Maybe

 

[begreen]

Shorter legs, shallower ashpan, bottom heat shielding, firebox design, etc. all affect the amount of heat radiated to the floor below - and in front - of the stove. To hear from someone who really knows, contact Jotul and let us know what they say. I also wonder why the F3CB doesn't have a name.

 

[MountainStoveGuy]

I am pretty sure i answered your question, its just not what you want to hear! lol.

 

[MountainStoveGuy]

They have had several number only stoves... 602, series 8, Series 3, 3cb, the Nordic qt was only the f100 for a while, untill they figured out that QT sounds like cutie. Lame.

 

[Planeweird]

Shorter legs, shallower ashpan, bottom heat shielding, firebox design, etc. all affect the amount of heat radiated to the floor below - and in front - of the stove. To hear from someone who really knows, contact Jotul and let us know what they say. I also wonder why the F3CB doesn't have a name.

I'll be heading out for another mission soon, so I'll try and do that when I have some downtime at a hotel. I really am curious about the specifics.

 

[onesojourner]

thats part of the reason I went with the nordic over the 3cb.

 

[CarbonNeutral]

What does non-combustible really mean? tiles on a single layer of hardibacker over a wood floor (with an r-value of 0.3 or so), or a hearth that has the 'default' r-value of around 0.8?

 

[onesojourner]

the guy at my stove store said you could through down a piece of sheet metal in front of it and it would meet the requirements.

 

[webby3650]

They have had several number only stoves... 602, series 8, Series 3, 3cb, the Nordic qt was only the f100 for a while, until they figured out that QT sounds like cutie. Lame.

I had the 606 and 118, I paid $2,000 for my new one and I still got one with only a number, AHH! but this one has an F in front of it!

 

[begreen]

F118CB = The Black Bear

 

[firefighterjake]

What does non-combustible really mean? tiles on a single layer of hardibacker over a wood floor (with an r-value of 0.3 or so), or a hearth that has the 'default' r-value of around 0.8?

Most folks would probably say non-combustible simply is that . . . hearth protection that does not readily catch on fire from spilled embers which could be tile, brick, Durock, cement, slate, etc. Personally, while I only needed non-combustible protection with my Oslo I opted to add a bit of R value by using two layers of listed Durock . . . 1) it gave me a little more peace of mind and 2) if I change out my stove some day to a stove that requires listed R value from the hearth I may have enough of a R value (or a start at least) with the hearth I have already built.

 

[firefighterjake]

the guy at my stove store said you could through down a piece of sheet metal in front of it and it would meet the requirements.

Well . . . that depends on your situation. Yes, technically the sheet metal would meet the manufacturer's requirements, but here in the Big City our Fire Inspector requires listed floor protection for all stoves and pellet stoves to follow NFPA 211 . . . and in addition as the AHJ signing off on the stove installations he feels the small additional expense to add listed floor protection -- even for stoves that do not require any R value protection -- is worth it. For what it's worth, I tend to think a little more about safety than expense with these kinds of things and think his reasoning is sound . . . for this reason here in Bangor putting down the sheet metal by itself would not pass muster which could be a potential problem if the insurance agent is requiring the Inspector to sign off on the install. This is a case where it is always a good idea to check with the insurance company, Fire Inspector/FD and any other interested parties before going ahead with the install.

 

[webby3650]

F118CB = The Black Bear

Mine was a 70's model, I didn't think it was called The Black Bear WAY back then.