New to Grandpa Fisher - not getting a lot of heat

[Drachen]

We just purchased a house in Eastern Tennessee. There is what I think is a Grandfather Fisher stove in the downstairs family room. After the season, I think I need/want to replace the stove pipe from the stove to the chimney, the former owner has the pipe going into the stove connection rather than round the stove connection.

Chimney was inspected and was said to be in good condition. I have seasoned fire wood. We can get decent fires going, but not what I'd call a roaring fire. My problem is that even after hours of having a fire going there isn't a whole lot of heat coming from the stove. A stove that size should be able to heat most of my house, and it doesn't even make the one room it's in very hot.

From this forum, I think I will look to add a damper inside the stove. There is the small round damper in the stove pipe. If I close that damper even a little with the doors open, I get a ton of smoke in the room.

Is the stove meant to be used with the doors closed? With no internal damper, and the pipe damper open, is alot of the heat going up the chimney? I've owned a lot of wood stoves, and never had this problem.

PS: I've spent a day ready all the posts. I've learned alot (maybe more than I knew could be learned).

Roger

 

[coaly]

Welcome to the Forum;
First, the trademark name given to your stove is a Grandpa Bear. (If it has 6 bricks across back) The search feature or Google search works best when the proper terms and name is used. I'll fix the title so others can find this information as well. Your problem is probably due to chimney or wood. You're right, it should heat at least 2000 sf area, probably more where you are unless extremely drafty..

The stove is a radiant heater with doors closed. The design of double doors was for fire viewing with doors open and screen in place. This allows most heat to escape directly up flue and is not considered a radiant heater in Fireplace Mode. The flue pipe damper becomes your only control in Fireplace Mode since it is then an open fireplace and not an air tight stove.
I think you mean a baffle plate inside stove. There are air dampers on the front for air intake and there should be a flue pipe damper in the first section of connector pipe. Later double doors had a Smoke Shelf Baffle. You can do that, depending on chimney and flue.

The connector pipe is correct and should be inserted INTO the stove outlet, not on the outside. All pipe joints should be the same way with male crimped end facing down. This prevents any liquid from condensed water vapor inside pipe from leaking out of joints and it runs back into stove to be consumed.

Closing the damper slightly will not cause smoke roll in when connector pipe and chimney flue are correct. Make sure there are no other openings into flue like for other appliances or leaking clean out doors.
We need to determine if it is a fuel or drafting issue first.
How long has the wood been stored and how long since it was split?

A picture of your set up would be best. We need to know if this is a top or rear vented stove, chimney flue diameter and height, length of indoor connector pipe, number of elbows and length of any horizontal runs. Is this a masonry chimney or insulated metal chimney?
You will need a pipe thermometer for proper operation. As you have probably read, the object is keeping flue gasses above 250* to the top of chimney flue and this is the easiest way to measure that.

It should roar up the stack when starting with kindling with air intakes open about 3 turns. You should need to partially close the pipe damper until you can't hear it roar to keep heat in the stove to help ignite larger pieces. Then close intakes to about 2 turns as it catches and comes up to temp. That is approx. 600* stove top temp. Turn down to about 1 turn each for normal operating temperature. More or less for heat desired.

 

[Drachen]

Let me see if I can answer all the questions:
The wood was split and stored before last spring (when we 1st looked at the property). It burns quite well.
As far as I can tell the woodstove downstairs shares a chimney (but not a flue) with a wood insert upstairs.
The woodstove chimney connecting is about 5 1/2 feet or so above floor, there is a clean out door just above floor level, directly under connection.
The stove vents from the back. There is a elbow from the stove, a straight piece of vertical pipe and another elbow into the chimney.

Sort of as a test, last evening I started a fire and when it was going well, I shut the doors and had the door vent wide open, I slight closed the damper on the stove pipe. Fire stayed going well, not roaring but more than smoldering. After an hour or so, I put more wood on the fire and closed the vents a couple of turns each. 2 or so hours later I came back, and checked the stove. Fire was still going, with some flames when I opened the door. But the room was still only moderately warm. I would not have thought a stove was going in the room if I didn't know already.

Welcome to the Forum;
First, the trademark name given to your stove is a Grandpa Bear. (If it has 6 bricks across back) The search feature or Google search works best when the proper terms and name is used. I'll fix the title so others can find this information as well. Your problem is probably due to chimney or wood. You're right, it should heat at least 2000 sf area, probably more where you are unless extremely drafty..

The stove is a radiant heater with doors closed. The design of double doors was for fire viewing with doors open and screen in place. This allows most heat to escape directly up flue and is not considered a radiant heater in Fireplace Mode. The flue pipe damper becomes your only control in Fireplace Mode since it is then an open fireplace and not an air tight stove.
I think you mean a baffle plate inside stove. There are air dampers on the front for air intake and there should be a flue pipe damper in the first section of connector pipe. Later double doors had a Smoke Shelf Baffle. You can do that, depending on chimney and flue.

The connector pipe is correct and should be inserted INTO the stove outlet, not on the outside. All pipe joints should be the same way with male crimped end facing down. This prevents any liquid from condensed water vapor inside pipe from leaking out of joints and it runs back into stove to be consumed.

Closing the damper slightly will not cause smoke roll in when connector pipe and chimney flue are correct. Make sure there are no other openings into flue like for other appliances or leaking clean out doors.
We need to determine if it is a fuel or drafting issue first.
How long has the wood been stored and how long since it was split?

A picture of your set up would be best. We need to know if this is a top or rear vented stove, chimney flue diameter and height, length of indoor connector pipe, number of elbows and length of any horizontal runs. Is this a masonry chimney or insulated metal chimney?
You will need a pipe thermometer for proper operation. As you have probably read, the object is keeping flue gasses above 250* to the top of chimney flue and this is the easiest way to measure that.

It should roar up the stack when starting with kindling with air intakes open about 3 turns. You should need to partially close the pipe damper until you can't hear it roar to keep heat in the stove to help ignite larger pieces. Then close intakes to about 2 turns as it catches and comes up to temp. That is approx. 600* stove top temp. Turn down to about 1 turn each for normal operating temperature. More or less for heat desired.

 

[coaly]

Something is obviously wrong with what appears to be your draft or lack of draft at stove collar. This is acting like a restriction in the chimney, connector pipe or clogged screen at top.
Make sure the clean out door doesn't leak air into the chimney flue and the flue has no other leak into it.
Make sure the connector pipe isn't pushed into chimney flue too far blocking off flow.
Is flue round or square, and clean to the top? Diameter of flue is very important to the top. Did you inspect it or measure it from bottom or top?

You should never have to open both air intakes more than 3 turns. (about 3 only when starting) It should roar with that much air and need to be closed to about 2 turns as it comes up to temp. Normal operation should be about 1 turn each.

The chimney is the most important and is the engine that makes the stove work. The inner flue should be no larger inside than 8 inches all the way to the top. The best is a metal insulated chimney or insulated liner. The chimney height should be at least 15 feet from stove base to top.

What has to happen is hot gasses rise up flue keeping it above 250* to the top. (this is why insulated liner is best to stay hotter inside) The rising gasses create a low pressure area in connector pipe and stove which allows the higher air pressure from atmospheric air pressure to PUSH into the stove. The adjustable Intake area is what increases and decreases the air coming in to supply oxygen. Make sure you're getting free flow up pipe and chimney and that you have unrestricted air pressure in the area of stove. Radon fans and other mechanical blowers or furnaces can reduce available air pressure decreasing the push into the stove. The problem is usually found covering these basics first.
Any leak into the chimney flue is cool air that slows or stops the draft which stops air getting into stove.

Is this an older Grandpa with flat top doors or newer Grandpa III with arched top doors and baffle plate inside?? Can you see the outlet opening inside stove through open doors ?
8 inch outlet on stove, 8 inch pipe, 8 inch flue?

 

[Drachen]

Something is obviously wrong with what appears to be your draft or lack of draft at stove collar. This is acting like a restriction in the chimney, connector pipe or clogged screen at top.
Make sure the clean out door doesn't leak air into the chimney flue and the flue has no other leak into it.
Make sure the connector pipe isn't pushed into chimney flue too far blocking off flow.
Is flue round or square, and clean to the top? Diameter of flue is very important to the top. Did you inspect it or measure it from bottom or top?

You should never have to open both air intakes more than 3 turns. (about 3 only when starting) It should roar with that much air and need to be closed to about 2 turns as it comes up to temp. Normal operation should be about 1 turn each.

The chimney is the most important and is the engine that makes the stove work. The inner flue should be no larger inside than 8 inches all the way to the top. The best is a metal insulated chimney or insulated liner. The chimney height should be at least 15 feet from stove base to top.

What has to happen is hot gasses rise up flue keeping it above 250* to the top. (this is why insulated liner is best to stay hotter inside) The rising gasses create a low pressure area in connector pipe and stove which allows the higher air pressure from atmospheric air pressure to PUSH into the stove. The adjustable Intake area is what increases and decreases the air coming in to supply oxygen. Make sure you're getting free flow up pipe and chimney and that you have unrestricted air pressure in the area of stove. Radon fans and other mechanical blowers or furnaces can reduce available air pressure decreasing the push into the stove. The problem is usually found covering these basics first.
Any leak into the chimney flue is cool air that slows or stops the draft which stops air getting into stove.

Is this an older Grandpa with flat top doors or newer Grandpa III with arched top doors and baffle plate inside?? Can you see the outlet opening inside stove through open doors ?
8 inch outlet on stove, 8 inch pipe, 8 inch flue?

It has flat doors, no baffle inside. I can see the outlet in the stove when the doors are open. 8 inch outlet and 8 inch pipe. I'm not sure about the flue, but it's rectangular, not round. It was inspected when we bought the house. Report said it was in good condition. There is nothing else on this same flue. Stove is on 1st floor, so to top of chimney it has to be 30 feet or so.

 

[coaly]

Do you know the year built? (chimney)
I would remove the pipe going into thimble to make sure it isn't pushed into the flue blocking it off. Then use a mirror to look up the flue to make sure it is open all the way up. The inside dimension can be measured when the pipe is removed as well. An extremely oversize flue like 12 X 12 or flue built originally for a fireplace will not heat correctly, and you will need to know the exact flue diameter to install a baffle. I assume you will find 7 1/2 square clay liner, but you never know. I don't know how long it has been since inspection, but critters build nests and other things cause blockage.
Do you use the Insert connected to the other flue with no problem? This will eliminate the possibility of cross drafting into the other flue.
Was this inspected by a sweep or a home inspector? Do you know if they inspected from the top or bottom? You may need someone who knows what to look for like missing mortar between joints allowing cool air into the flue decreasing draft. If you can't tell with a mirror, a camera with flash may show you something up the flue. If you can't see straight up through the top, I'd run a brush of the correct size through it to make sure it is open and clean to the top.

 

[Drachen]

so much for trusting an home inspection...

The pipe from the stove was not too far into the chimney. There is a round clay pipe about 1 foot long, horizontally until it gets into the flue. The flue itself is about 10x10. I tried looking up the flue using a mirror and could see nothing. I put a 2 foot flexible ruler up and immediately encountered a big chunk of "soot". It was almost like styrofoam, very light but in chunks. I cleared that and I'm now able to see light coming from above. I will be having the flue cleaning this weekend.

The home inspection said the chimney was in good condition and "probably" should be cleaned "at some point". I intended to get it cleaned this season, but with so much going on with moving in, I didn't get to it in time.

When I looked into the flue and then opened the clean out door, it looks like the clay flue does not go past the opening in the chimney. From the stove pipe down seems to be just cement block. I'm not very happy about that.

I read on this forum where people have fitted a damper inside of the stove (for those that didn't come from the factory that way). Is that recommended? If so, any tips/information I should be aware of?

Thank you for taking the time to consider my problems. I will post again after the flue has been cleaned.

Roger

 

[coaly]

I guess you could call that a "restriction" Good you found it before it got cooking in there.

I would not suggest installing a baffle plate with that large of a flue diameter and height.
It is always best to have the flue the same size as stove outlet all the way to the top.
It is imperative to keep the flue gasses above 250* all the way to the top. Water vapor from combustion condenses on the flue walls allowing smoke particles to stick. This can build up creosote rapidly. Keeping the flue the same size as stove outlet requires less wasted heat left up the chimney to maintain the 250* minimum required. The Smoke Shelf Baffle that was added to the later double door stoves decreases smoke particulate and directs more heat to the stove top. That is great when you have an efficient chimney. You need an insulated liner in that large of a flue for many reasons, even with your stove used as it is without baffle.
The main reason, and the reason why you have so much creosote, is due to allowing the hot rising flue gasses to expand into such a large area. Expansion cools the gasses and you can't heat that large of an area and burn efficiently. The stove outlet being 8 inches round is 50.24 square inches. You are allowing that to expand into a 100 square inch diameter flue which requires twice the amount of heat left up. The taller the chimney, the more heat required to keep it hot all the way up. A larger chimney doesn't have more draft. It is CAPABLE of more draft when you allow more heat up it, increasing draft. So you need a efficient chimney to use a efficient stove.

Fisher single door stoves were built with 6 inch outlets. The largest firebox size was comparable to yours, and a 6 inch efficient flue works great. Your stove was built with the larger 8 inch outlet for open door burning and when the stove was designed many were connected to existing fireplaces with much larger flues. A fireplace needs that, but a stove with controlled combustion with a smaller outlet doesn't allow enough heat to escape to make the chimney work and stay clean. It is technically against code to reduce the pipe or flue smaller than stove outlet. This code was written to prevent reducing what was built with the minimum flue size, however yours was made oversize and it has been proven they physically work fine reduced to 6 inches. That is by far the most efficient and would be required for most all new stoves. You can tell by seeing ads for these stoves for sale the percentage that have reducers on the stove reducing to 6. It is very common, but technically not legal. So adding a baffle at this point compounds the problem of a cool flue.

Your Insert in the other flue requires a direct connected liner all the way up as well. Installing an Insert into fireplace and using the existing flue is considered a "slammer" and no long an approved method.

When you get that rising column of hot gasses in the flue to make the low pressure or vacuum in the stove, it will get oxygen in the firebox allowing the stove to heat up heating the area it's in. The larger the flue, the more you need to leave up and the less usable heat you have inside. The liner pays for itself in fuel quickly ! The you can make the stove more efficient with a baffle.