MORE Hearthstone Green Mountain 60 - ISSUES

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LakeCabin

New Member
Mar 13, 2021
40
Maine
We just bought a Green Mountain 60. Initial experience is very similar to what Drylightning described a few weeks ago. It's nearly brand new. Another customer had it for a week and gave up.

This replaced an old Hearthstone Harvest in a cabin we recently purchased. We lit the Harvest a number of times and it appeared to work fine until the damper broke and we discovered lots of other stuff was broken and needed replaced.

To get the GM60 to run we have to start with the door ever so slightly cracked --which is what it tells you to do in the manual except you can't close it. If I close and latch it the fire goes out. If we run it with the door until we've burnt two or three logs and there is a good amount of glowing hot wood in the bottom we might keep a flame going for 5 to 10 minutes minutes after latching the door. If the door has been latched for a while I have to ever so carefully crack the door and wait for the logs to re-light to avoid lots of smoke coming out the door. I tried using the catalytic when it was hot enough but that doesn't help and probably makes it worse. Hard to tell. The wood is seasoned. As we inherited the wood I tested it with a moisture meter and it's fine. The air damper is wide open. But it really doesn't make any difference open or closed because as the only way the GM60 runs is with the door slightly cracked. I checked the metal plate/tag wasn't blocking the air intake as suggested by Cabinwarmer in the earlier thread. I unlatched the tag and it didn't make any difference.

I tried Cabinwarmer's suggestion of doing a top down start. If I latch the door it fills with smoke and starts to go out. If I unlatch it very so slightly it's a roaring fire again during startup. No in-between.

Our setup is different from Drylightning's. It's a straight up steel chimney. the Ceiling is 8 foot from the floor. And there is a shallow slanted roof about that. I haven't measured the chimney/roof but I'm guessing there's another four feet. I noticed Wood Stover's comment in the earlier thread that the minimum height is 14 feet. I checked the manual and that's exactly what it says. So I think the chimney needs to go up at least 2 to 3 more feet and see if that helps.

Another note is that it's often fairly windy where we are. Average wind speeds outside during the first fires I'm describing above in at least the mid twenties. When I hear a gust outside, the flame seems to swish around. Not sure if I'm imagining that or it's real.

Aside from extending the chimney, anything else I should be considering or could an extra few feet of chimney be enough to fix the problem?
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,580
South Puget Sound, WA
This sounds like weak draft. I would go for 15' total flue height from the top of the stove to chimney cap. Brace the chimney at 5' above the roof surface.

How was the wood moisture checked? Was the firewood resplit and then tested in the center of the freshly exposed face of wood? What did it read?

What was the outside temperature when burning? That will also affect draft. The colder the outside temp the stronger the draft will be.
 
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LakeCabin

New Member
Mar 13, 2021
40
Maine
Thanks. I checked the moisture with one of those two pronged moisture tools. I just split some wood and I was getting readings of 11% to 15% in the inside.

The cabin is at 1750 feet. It's facing out onto a small lake. There are trees at the back and one side but the front (lake side) and other side, the corner where the stove is located, is fairly exposed.

Looks like the installers will come back next week and extend the height of the flue.
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,580
South Puget Sound, WA
Sounds like the wood and the altitude are not an issue. Keep us posted on how things progress.

One other test you could do while waiting... Try opening a nearby window an inch. See if that helps.
 
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LakeCabin

New Member
Mar 13, 2021
40
Maine
Tried opening the window a bit and that didn't seem to help. Thanks.

I am getting a lovely dirty build up on the front glass. I will let you know what happens once I get the flue extended.
 

webby3650

Master of Fire
Sep 2, 2008
11,061
Indiana
What moisture meter are you using?
 

webby3650

Master of Fire
Sep 2, 2008
11,061
Indiana
11% is almost unbelievably low. I’m betting there’s an issue with your wood. What’s the history? Split and stacked for how long?
 
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LakeCabin

New Member
Mar 13, 2021
40
Maine
Tavool MT270. I don't know the history of the wood which is why I bought the moisture meter. We bought the cabin in December and inherited all the wood. The previous owner stored all the wood in the basement. It's an unfinished concrete basement built 30 years ago. The basement is dry. The wood is stacked a few feet away from an oil furnace. the largest part of the air ducting (which is not insulated) runs over where the wood is stacked. In December I built a proper wood rack and moved nearly all of the wood outside. There's still some left in the basement as the rack wasn't big enough to take it all. The wood I am burning at the moment is from the basement. Relative humidity in the basement at the moment is about 42%. At the beginning of the week it was around 36%.
 
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tabner

Burning Hunk
Jan 17, 2019
172
Eastern CT
Can you take a photo from underneath the stove, looking up at the air intake hole? There was a guy on here a couple months ago with a GM40 and he has some strange metal flap bolted over the hole that none of the rest of us with these models recognized. He said it improved after he removed it.
It's a long shot, but just figured I'd mention it
 

tabner

Burning Hunk
Jan 17, 2019
172
Eastern CT
I found the old thread. Again, it's a long shot, but just came to mind in case it helps
 

LakeCabin

New Member
Mar 13, 2021
40
Maine
Can you take a photo from underneath the stove, looking up at the air intake hole? There was a guy on here a couple months ago with a GM40 and he has some strange metal flap bolted over the hole that none of the rest of us with these models recognized. He said it improved after he removed it.
It's a long shot, but just figured I'd mention it
I did take a look underneath and it's fine. When you move the slider a gap opens. Compared with my old Hearthstone, it's a relatively narrow intake but I understand that's a feature of the newer stoves.

The installers tried lighting a fire yesterday and replicated my experience. They are talking to Hearthstone but I think it's likely that they'll extend the chimney. I will report back with details when I know more.
 

LakeCabin

New Member
Mar 13, 2021
40
Maine
The dealer talked to Hearthstone. "They are sending a low primary air replacement part. It is supposed to help." Not sure what that is. A replacement for the existing air intake?

And "They also recommend extending the chimney above the peak of the house approximately (6 to 9 feet) and supports. Rough estimate is under $1000. It is still not guaranteed to fix the issue."

Hmm. It does a good job burning money.
 

jetsam

Minister of Fire
Dec 12, 2015
5,283
Long Island, NY
youtu.be
Pick a good sized split. Warm it up overnight in the main house, split it, and use your tester on the fresh split face. Ideally the wood you test will be from the middle of the split, 70°F, and freshly split.

Now bang those two splits you just split together. They should clink like windchimes (and possibly actually ring) if the moisture is anywhere near 15%. If they go thud and don't clink, and your tester still says it's below 25%, get your money back for the tester.

Not saying that there are not other issues- but you should always rule out the wood as a problem first, and I don't think you've done that yet.
 
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cabinwarmer

Member
Sep 11, 2020
183
SE PA
Sorry to hear your issues. I have noticed a considerable amount of poorer performance with my GM 60 and wood MC. More then I would have expected, or have seen in the past with a non CAT stove. If I burn moist wood at all, it acts just as you describe. When I put in known dry ash, the stove burns perfectly. The build-up on the glass will happen. Mine does it a bit more than I like, as I let it go out each night. I clean it regularly, (just me, I like to see the fire for control reasons). I have 20+ feet of flue straight up and have MORE draft than I need. You say the top down start slows down and even stops when the door is closed. If you are using small kindling and building the start properly, it would lead me to think draft issues. Is the flue recently cleaned? New? That kindling should go right up quickly and burn fast if dry. I am still burning an old Upland 107 in my shop and it is a completely different mindset in operation to the CAT. Also, take a quick look in the very top of your firebox at the CAT's themselves. Not your primary issue, but it sounds like to me they may be a bit full of ash after the previous owner and any wet wood burns, if that is what you had. You can simply brush them off with a paint brush. They may need more cleaning via the back panel after you solve the first issue. I believe your installer should be able to read the draft via a manometer, if he is top notch. Most guys do not have one. Might be worth asking.
 

LakeCabin

New Member
Mar 13, 2021
40
Maine
These are the installation instructions for the Lower Primary Air Opening Kit. It's hard to tell from the instructions how it differes from the part it replaces so I guess I have to wait and see how it differs and how it might make a difference.
 

cabinwarmer

Member
Sep 11, 2020
183
SE PA
Good Day LakeCabin, very interesting and thanks for posting these instructions. I am wondering why Hearthstone has recommended this replacement. How could this piece get damaged? Different size? Gaskets might be blocking air flow? Keep your eye on the replacement procedure and ask questions. And do I side by side comparison before the installer puts the unit in. Take pictures. Did you happen to notice how your bottom soapstones are laid on the floor of the firebox? When I put mine in, you had a choice on which side/position to "push" them to. I chose to push them towards the back leaving room for all possible air flow. They will fit differently if you put them in N/S or E/W but a small amount, fyi. Please keep us posted, thanks!
 

tabner

Burning Hunk
Jan 17, 2019
172
Eastern CT
If you review that Green Mountain 40 Not Working thread I linked above, from a couple months ago, that user also mentioned that hearthstone sent an updated Air Inlet out and had the installer put it in. He actually said they called it a "recall". Unfortunately for him it did not seem to help. I am curious about this too. I noticed the date on those instructions you posted (thanks for sharing) is January of 2020, so clearly they've been aware of this problem for a while. It's interesting though, I think @Nigel459 bought his GM40 prior to that date, and he has not mentioned the 'recall'. Something fishy going on here, it would be really nice to get an explanation from Hearthstone on what exactly the part change is.
 
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LakeCabin

New Member
Mar 13, 2021
40
Maine
I will take photos of the new part and the old part if I am there when it is installed and try and determine the difference.

Cabinwarmer: Interesting that you mention the soapstones in the fire box. Just before I left last weekend I noticed that the soapstones in the top of the box didn't appear to be fitted together properly. I have since looked at the instructions and they are not. I will try to fix this when I am up this weekend as well as clean the box, air intake, cat as suggested above.

The technical documents for all Hearthstone wood stoves old and new are here. The GM60 docs are here.
 
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LakeCabin

New Member
Mar 13, 2021
40
Maine
If you review that Green Mountain 40 Not Working thread I linked above...

Thanks. I did read that thread after you linked to it. I had forgotten about that the "recall". It was only after I read the thread that my dealer said that Hearthstone was sending a replacement part that might help. The word recall was not used. But clearly if they are saying a new part might help they are aware there is some issue.

As soon as I know more about the part I will post more information.
 

cabinwarmer

Member
Sep 11, 2020
183
SE PA
LakeCabin, the top pieces of the firebox are the two baffle boards, they are not soap stone but made of a lighter material. They are fragile, use care. It depends on how bad they are off, but how did your installation tech miss that? They have a direct effect on draw I would think if not installed properly. When you take the baffles out, (remove bar clip across the front)be careful the soapstones from the side do not fall inward, they will break against the cast iron. I cut two pieces of wood, made an X support across the back to hold the sides up. The side stones hold the back stones in place. While you have the baffles out, that is when you clean the CATs from the inside. You will plainly see them. PS - I have heard nothing of any "recall" on my GM60. My dealer experience has not been good, I would bet they would not contact me without me calling them with a complaint.
 

LakeCabin

New Member
Mar 13, 2021
40
Maine
Thanks for the advice about fixing the two baffle boards. I will be careful.

The 'installers' were nice enough but I doubt their expertise. The installation was: get it into the house and hook up the chimney and we are are done. At some point in the process I asked them about the height of the existing chimney and they didn't have much to say other than to state the obvious that it may need to be extended if it doesn't work. Afterwards, having read comments here, I realized that if they'd read the installation instructions with more thoroughness they would have realized it was likely to be about 2 feet lower than Hearthstone's minimum height.

They didn't do a test light and didn't check the inside. This had been installed somewhere else briefly so it was already fully assembled. As I am sure you are aware, the top baffles have cut-outs in the middle that overlap each other. One of them appears to be sitting up a bit so that they are not tightly overlapped.
 
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LakeCabin

New Member
Mar 13, 2021
40
Maine
So the installer came back today and stuck on another three sections of chimney (9 feet?) and added bracing so it's a decent amount above the roof peak. Looks crazy compared to anything else around here. I wonder about the bracing.

I was dealing with a contractor on another matter (bad timing) when they were trying to install the replacement part but when I got to talk to them they said they couldn't get the old part out as the hex driver was spinning on the bolt that held in in place. They speculated that when it was installed originally the thread had been stripped. Great. I still have the new part. It doesn't look that different from what I can see of the old part. I may get a hex driver and see if I can manage to get the bolt out. The difference between old and new part may be that the air hole is ever so slightly bigger. I can measure both holes without removing the old LPAO. They also fixed the baffle at the top so it is seated properly.

They lit a test fire with some small sticks and some sticky gel substance and they didn't think the fixes were working. I think they had the cat engaged but when I asked about this I was told it wasn't. My reading of the manual is that it is engaged when the handle is pointing to the back rather than straight down. They had it pointing to the back. After they left I shone a light up into the top of the box and looks like when the handle is down the cat is being by-passed. Weather here today is in the mid to high twenties. There is a breeze outside. Local weather says 14mph with higher gusts.

After they left I took all the sticks and stuff out the fire box and dumped them in an ash bucket. There was no real heat in there. I picked it up with my hands so I don't think the test fire was such of a great test. I built a proper Hearthstone-recommended top-down light with a little paper. Moved the handle to straight down (so cat not activated). Had a roaring start but with air intake wide open and door cracked. It burnt all the way down and I added more wood. Temperature indicator was well into the middle of the cat activation zone. Once there was a lot of heat in the bottom and the stove was giving off a lot of heat I could latch the door (still with air intake fully open) and the flame kept going for ten minutes or more. I also tried the cat when the fire was going and door latched and that as one might imagine didn't help. So I opened the bypass again. The stove is still hot and temp is reading in the middle of the cat zone. There are a couple of charred logs in the bottom. If I crack the door they'll re-light immediately and once they are going I can latch the door again and after ten minutes or so the flame will go out and there are two red glowing logs (air intake is fully open). Presumably they are still burning. Not sure exactly what's normal in these 2020 stoves but not sure this is it.

I haven't had a chance to take the back off and check the cats to make sure they are clean but sort of irrelevant given that I'm not able to activate the cats at the moment. I also wonder about the air intake. If there was wood and ash at the front of the fire (which I have tried to avoid) what is to say there could be some obstruction I can't see further limiting the already very limited intake? I'm not sure how you'd clean any ash that went down the small hole. Vacuum it? Take the LPAO out and vacuum? Latter is a bit hard if the bolt won't come out.

When I have a moment I will try to measure air intake hole on the old and new LPAO and tell you if there is a difference. I will post photos of the new one and the old one if I manage to get it out.

Update: looks like the hole on the new one has a diameter of 3/8".
 
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cabinwarmer

Member
Sep 11, 2020
183
SE PA
So the installation guys just threw their hands up and left and left you with the replacement part? They are from your local dealer? Did the top down burn with the door closed at all? If you had the cat reading in the middle of the zone, your flue temp is around 450-500 F. That is plenty hot for that stove to run. Yes, the installation guys had the cat engaged during their test. The handle should be down until the gauge shoes active, then push towards the rear. Have you tried a known dry wood source?