New Green Mountain 80 user

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UpstateGM80

New Member
Dec 13, 2025
8
Glens Falls
Just bought a New Green Mountain 80.

A couple of issues. The ceramic front needs to be cleaned EVERY day and by the end of the day you can't see in.

Didn't arrive with a cat temp probe and as this is our first cat stove we are guessing some.

The stove temp seems MUCH warmer than the flue temp.

Some minor puffs of smoke into the room.

Old stove was a non cat defiant from Vermont casting company.

Learning this new stove isn't easy yet. But I love seeing the firebox, size of firebox, and efficiency so far.
 
Didn't arrive with a cat temp probe and as this is our first cat stove we are guessing some.

The stove temp seems MUCH warmer than the flue temp.
It should have a cat thermometer. How is the flue temp being measured? With a probe thermometer in double-wall pipe or with a magnetic surface thermometer?
 
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Flue temp is surface. Pipe is single walled.

[Hearth.com] New Green Mountain 80 user
 
The internal flue gas temp in the single wall is roughly double the surface reading, or about 600º in this case. The stove top temp of 400º is ok but on the lower side. Note that those scales appear to be for a Hearthstone soapstone stove top. Cast iron stove tops often run in the 500-700º range.
 
This is a soapstone green mountain 80. No soapstone on top so run it a little hotter?
TheGM series are basically cast iron stoves with soapstone firebricks at the back.

See if running the stove 100-200º hotter clears up the glass.
 
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A cat stove can be like that, dark windows.
The cat allows you to run the stove a bit lower,.i.e. smoldering, because the cat will clean up the smoke.
That means that if you run it properly, your flue will be clean but given that the gases see the window before they get combusted by the cat, windows can get dirty.

Generally they can be cleaned off by running the stove high for 20-30 mins or so.

And they'll get.less dirty when you run the stove higher.
And they'll get dirtier if the wood is not optimally dry.
 
Keep the stove top below 750 max. However, I'd be more comfortable first knowing that the cat temp is ok at that stove top temp. The cat should be kept below around 1500º.

One thing to check when the stove is cold is that the baffle bricks are properly in place, all the way back, and pushed together in the center.
 
I am working on the dealer to get me the cat temp probe that didn't arrive with the stove. Won't run it hard until then better to have the info.

They were all the way back this morning but I will make sure they are pushed together.
 
Keep the stove top below 750 max. However, I'd be more comfortable first knowing that the cat temp is ok at that stove top temp. The cat should be kept below around 1500º.

One thing to check when the stove is cold is that the baffle bricks are properly in place, all the way back, and pushed together in the center.

I agree, tho new cats often exceed that temp before they settle down.
 
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Mine was hyperactive far longer than a week. (And a week doesn't say anything, it's burning hours that matter.)
It took about a cord to settle down.
Different.stove but cats are basically all similar. Only a few mfgs
 
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For me when it didn't run off the cat gauge scale anymore.
 
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