fisher grandpapa hearth problem

[henrod]

hi all new here. I have some ? hope someone can help well here we go. I have a grandpapa fireplace stove double door and has a 8 inches flue I read I can reduce to 6 because the 8 was for open door fire. I all so was wondering how close you can have the bottom of the stove to the hearth cause I need to go down 2inches to make it work with the hearth I have. I look up prices for a new on and called. a man he ask me the r value of it. I read that it needed to sit on a 3/8 asbestos millboard. I like to cut the legs on it to make lower can I. I am going to look to see if I can find a 3/8 hearth online but 400 dollars wow. does anyone no the r value? seen jimmy had a heat shield on bottom of his that be nice if I had but don't stove in house no welder. hearth pad 2 inches help.! I all so have a reducer; and it slide over 8 inch pipe should I drill holes to screw.it fit on pipe tight.. oh the man told me that the hearth pad he has was 2,86 r value and most others are just 1.4.

 

[pen]

This manual doesn't seem to mention anything about being able to reduce the chimney area down to 6 inches. I believe some Vermont Casting Stoves have allowed that but I can't remember seeing that for a fisher, but Coaly may know different.

The manual I'm looking at says this



By what's shown in the middle left of that pic from this manual https://www.hearth.com/images/uploads/fischermanual.pdf I don't see dropping to 6 inch as being an option that's approved. Even if it works, my concern would be getting the insurance company to be OK with installing the stove in a manner that is not approved by the manual.

Is this a traditional fireplace (all masonry construction) or are you wanting to put this inside an existing zero clearance fireplace? Is this stove the actual insert, or is at a free standing fisher you want to install like an insert?

 

[henrod]

Its is a free standing i want to hook it up and run pipe to tee coming down at the end of fire place and the chimney has a 6 inch liner. and tradition fireplace. TY hope coaly will have some input. I
read on here that the 8 inch was for if you burn with a open doors and screen. hmm look at manual looks like its not what I have. I have too put a pic on here.my has 4 trees on it...and the name fisher is split in half for doors .and no heat shield.

 

[pen]

As I understand, the reason they went to 8 inch for many of the double door models was for open door viewing (with the screeen). However, unless the manual somewhere suggests that is OK for the unit to be installed with a chimney of a smaller diameter, you are taking chances with the insurance company being OK with approving the installation. With a tall enough chimney I'm certain a 6 inch would work on the stove,,,, however, that doesn't negate the fact that if there ever was a fire associated with the stove that the insurance company wouldn't try to raise a fit,,,, that's my concern.

In the last 10 years I've had a hell of a fight for my house and my cabin to keep fisher (or similar non-ul approved stoves) in them. Just wanted to give you a heads up before you make an investment and end up in a bind.

pen

 

[henrod]

its is a free standing and looks like this wow pen . a friend gave it too me he was moving and had in house for 20 years. it look like thisthe chimney is 30 feet tall. and four feet wide and did you use single pipe.and

 

[coaly]

The benchmark standard of 3/8" asbestos millboard is a common requirement used by many manufacturers with a k-value of 0.84. (R .45) Many materials are rated by R value (higher better) and must be converted to k, (lower better)

Notice the manual also recommends brick covering over the millboard. (manual wording "desirable" does not mean mandatory; draw your own conclusion I guess) 4 inch brick = r .80 ; so with the 6 inch airspace provided by standard leg length; 1.25 was the minimum calculated r value "desired". I would hope that becomes "required" in todays legal terms. Keep in mind the first manual was written as the industry was evolving and so many were being installed across the country, insurance companies and local governments had to get involved and create safe practices that many are no longer considered safe. (such as the original Insert installation using the existing chimney flue)

Like pen posted, it's not a problem unless insurance company and codes are involved. Reducing the flue size will physically work, but NFPA 211 standard does not allow reduction in flue size of the stove outlet. It's very common to find them reduced from 8 to 6 with no smoke roll in problems when opening doors or even add on baffles.

Cutting legs down is very common on masonry hearth since it would be considered a non combustible. Reducing the airspace under stove requires higher r value, or preferably a bottom shield. Insurance and codes will still not allow it, since you are altering the appliance "as tested". That said, a shield 1 inch to 1 1/2 inch from bottom makes a huge difference. You can keep your hand directly under the center of stove in operation and find a cool floor compared to uncomfortably hot floor protector without the shield. Below is the model VI with floor and rear shields showing air flow.

 

[henrod]

thank you for input I seen a stove on here with heat shield . wonder what gauge they use and if you can just put one on the bottom and not back and it looks like the side are sealed so air flow come from front and go to back . not from side. the house had a mama bear single door but the owners took it. I have a friend that has a welder .think the user name on here who had it was top jimmy.

 

[coaly]

Yes, the bottom shield is closed on the sides. The picture from manual is a cut away view to show an inner shield. The VI was double on the bottom, single on the back.

First post in the Everything Fisher thread gives material specs;

ALL Fisher stoves are welded 1/4" thick steel plate, most having 5/16" thick tops. ALL steel plate construction is specified to be HRS or Hot Rolled Steel. Shield material is 22 gauge cold rolled steel.

 

[henrod]

thank you coaly I new I read it somewhere on here I been doing a lot reading on here a lot of input. I think I going to put a shield on it . and cut legs down 1inch; I have a big farm house I have to heat. wish I had that 10 inch flue stove lol just kidding.