Vermont Castings Merrimack/Montpelier

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SculptureOfSound said:
did you ever find the right amount of blockage - curious how much that was
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Yeah so I think I've settled in on 1/4 inch inlets into the secondaries which equals approx 60% reduction overall. Seems like a lot but the stove behaves so much better now. The primary air control actually has a meaningful impact at different settings now versus before it was basically just open/closed.

Even with a say 50% reduction I was still running into over-firing issues on a full load. The flue connector area temps would still climb to 900+ and glow a little bit. Now I can load it up full, close it down, get beautiful secondary action and just cruise and ~850 degrees at the flue connector area and nothings glowing.

Oh, and I'm noticing that the white ash film that would accumulate on the glass after a couple hot fires is gone. Someone in another thread mentioned that this was caused by excessive draft but I didn't believe it because everything I've read basically says I'm just barely situated for acceptable draft.

With a 17ft chimney and not incredibly cold environment there is no reason for me to believe that I have too much draft but I don't know how else to explain it. The stove was an absolute blast furnace before the mod. Now it's tame and controllable. Sure it takes a little bit more finesse to dial it in and not kill the fire when shutting the air down but as I understand that's the way these stoves are supposed to work.
 
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Awesome to hear! I too found the white film was greatly reduced after the mods. I'm sure it was caused by the secondary air coming out of the tubes so fast and just blasting the glass. That would push any fly ash to the glass where it would accumulate as the white film. With reduced secondary amount and velocity, (most of) the air gets pulled up over the baffle before hitting the glass, it should be primarily just air wash air hitting the glass and it stays a lot cleaner.
 
therealdbeau said:
Yeah so I think I've settled in on 1/4 inch inlets into the secondaries which equals approx 60% reduction overall. Seems like a lot but the stove behaves so much better now. The primary air control actually has a meaningful impact at different settings now versus before it was basically just open/closed.

Even with a say 50% reduction I was still running into over-firing issues on a full load. The flue connector area temps would still climb to 900+ and glow a little bit. Now I can load it up full, close it down, get beautiful secondary action and just cruise and ~850 degrees at the flue connector area and nothings glowing.

Oh, and I'm noticing that the white ash film that would accumulate on the glass after a couple hot fires is gone. Someone in another thread mentioned that this was caused by excessive draft but I didn't believe it because everything I've read basically says I'm just barely situated for acceptable draft.

With a 17ft chimney and not incredibly cold environment there is no reason for me to believe that I have too much draft but I don't know how else to explain it. The stove was an absolute blast furnace before the mod. Now it's tame and controllable. Sure it takes a little bit more finesse to dial it in and not kill the fire when shutting the air down but as I understand that's the way these stoves are supposed to work.
Click to expand...

I too have an unlikely high draft, but I think it has more to do with being on a hill. From flue collar to chimney exit I have about 25', but my clay liner is oversized for my stove, and I have single wall with a 90 elbow. My chimney is interior brick with a 7.5-ish inch square clay tile liner. If I'm slow on the turn down with really dry wood, the secondaries burn out of control even if I close the primary air completely. The opening for the shaker grate handle is slightly larger than the connecting rod, so this lets a tiny bit of bottom fed air into the box. I've discovered that burning a bunch of bark directly over the grate will cause it to close off with a giant clinker from the mineral deposits in the bark. If I use bio bricks with my cord wood to reduce overall moisture content, same thing. I've experimented with using aluminum foil on the outside of the stove to close the secondary inlet, but I can't really get to the inlet well enough to accurately close it down due to it being covered by a heat shield. Over time I am reducing the amount of fly ash on the glass and getting better and longer burns. Maybe my draft will reduce a bit after an insulated 6" liner with double wall stove pipe, or at least keep the flue hotter.
 
therealdbeau said:
Yeah so I think I've settled in on 1/4 inch inlets into the secondaries which equals approx 60% reduction overall. Seems like a lot but the stove behaves so much better now. The primary air control actually has a meaningful impact at different settings now versus before it was basically just open/closed.

Even with a say 50% reduction I was still running into over-firing issues on a full load. The flue connector area temps would still climb to 900+ and glow a little bit. Now I can load it up full, close it down, get beautiful secondary action and just cruise and ~850 degrees at the flue connector area and nothings glowing.

Oh, and I'm noticing that the white ash film that would accumulate on the glass after a couple hot fires is gone. Someone in another thread mentioned that this was caused by excessive draft but I didn't believe it because everything I've read basically says I'm just barely situated for acceptable draft.

With a 17ft chimney and not incredibly cold environment there is no reason for me to believe that I have too much draft but I don't know how else to explain it. The stove was an absolute blast furnace before the mod. Now it's tame and controllable. Sure it takes a little bit more finesse to dial it in and not kill the fire when shutting the air down but as I understand that's the way these stoves are supposed to work.
Click to expand...
Still havent gotten around to modding the tubes but its on the agenda. Have you noticed with the lower air inlet closed the fire doesnt get a complete burn.Every couple of days i have been running the stove with the primary air closed once the fire gets going and the lower inlets unblocked (i always only cover one of the holes)and getting more complete burns with regards to how many large coals i have left in the morning
 
Dazza80 said:
Still havent gotten around to modding the tubes but its on the agenda. Have you noticed with the lower air inlet closed the fire doesnt get a complete burn.Every couple of days i have been running the stove with the primary air closed once the fire gets going and the lower inlets unblocked (i always only cover one of the holes)and getting more complete burns with regards to how many large coals i have left in the morning
Click to expand...

I'm really not sure what, if any, difference it makes to block off the bottom air holes. I just can't tell a big enough difference either way to really make up my mind. Currently I have one side completely blocked and the other side about half blocked and I think I'll stick with that for now.

I'm overall very happy with this stove now after the mods. When I first got it I thought the 12 hours burn time in the brochure was a joke. I'd get 8 maybe 10 if I packed the stove really tight. After the mods, 12 hours seems easily achievable.
 
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therealdbeau said:
I'm really not sure what, if any, difference it makes to block off the bottom air holes. I just can't tell a big enough difference either way to really make up my mind. Currently I have one side completely blocked and the other side about half blocked and I think I'll stick with that for now.

I'm overall very happy with this stove now after the mods. When I first got it I thought the 12 hours burn time in the brochure was a joke. I'd get 8 maybe 10 if I packed the stove really tight. After the mods, 12 hours seems easily achievable.
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I think it must be the draft equation( your 17ft and my 30ft chimney plus the cold here in n.illinois) because i notice a difference big time with just one hole closed i have a magnet i just slide back and forth. That thing gets real hot so ive gotta be quick lol. Im just about out of wood so ill be shutting it down early. Had bad luck buying wood this year as far as being poorly seasoned and running the stove with the air assist stuck open really ate through it. Id buy more but getting some push back from the wife haha fire is running now with all air shut down and its like a blow torch so these tube mods will help for sure
 
Imo that is burning too vigorously if air is completely shut.

I found on the Monty that closing one intake hole did almost nothing, it would just pull harder on the other hole and just as much air appeared to be coming in.

I confirmed this by sitting right by the unit and watching the flicker pattern of flames in front of the air holes. Virtually no difference if just one hole was blocked. I had to block one fully and the other about 75% or even more for the flicker to slow down. Blocked fully the flicker would stop (on specific pieces in the airflow path). Of course this is only noticeable with the primary fully closed too, otherwise there would be flicker from the primary air.
 
Here's a video of mine with primary fully closed and only a half full firebox of pine (remember the Montpelier firebox is a lot smaller than the Merrimack!)

I get a bit more activity at the top and less primary flame if the wood is drier...ran out of my really dry good stuff over a month ago sadly.
 

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SculptureOfSound said:
Imo that is burning too vigorously if air is completely shut.

I found on the Monty that closing one intake hole did almost nothing, it would just pull harder on the other hole and just as much air appeared to be coming in.

I confirmed this by sitting right by the unit and watching the flicker pattern of flames in front of the air holes. Virtually no difference if just one hole was blocked. I had to block one fully and the other about 75% or even more for the flicker to slow down. Blocked fully the flicker would stop (on specific pieces in the airflow path). Of course this is only noticeable with the primary fully closed too, otherwise there would be flicker from the primary air.
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I swear i felt like something was not closed correctly i quadruple checked primary and the lower inlets all seemed okay but air temp is 5degrees right now so i dont have enough experience to know if that will increase the draft to create that intense burn
 
SculptureOfSound said:
Here's a video of mine with primary fully closed and only a half full firebox of pine (remember the Montpelier firebox is a lot smaller than the Merrimack!)

I get a bit more activity at the top and less primary flame if the wood is drier...ran out of my really dry good stuff over a month ago sadly.
Click to expand...
I have poorly seasoned wood but i have to buy it.. Ill be more prepared this year.. Where in wis are you located?
 
SculptureOfSound said:
Here's a video of mine with primary fully closed and only a half full firebox of pine (remember the Montpelier firebox is a lot smaller than the Merrimack!)

I get a bit more activity at the top and less primary flame if the wood is drier...ran out of my really dry good stuff over a month ago sadly.
Click to expand...
So that fire is running with the tubes modded also which helps keep it from getting out of control?
 
My Merrimack acted exactly the same before the secondaries mod. It's simply uncontrollable.

Here's a couple videos post mod. In these vids I have the bottom air holes both blocked off (still experimenting). Primary air fully closed. Started off as a full load with a couple Liberty Bricks in there as well so this is about as hot as it will get.
 

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That burn looks perfect Therealdbeau.

I'm not sure why I can almost never get my secondary air to come out so slow and even like that. Even with the mod they come out fast...just less air overall and I get a lot of blue wispy secondaries. No smoke from the chimney so I know I'm burning pretty clean. I wonder if it's the difference in how we modded the tubes or if it's the wood (95% pine here for this season) or what
 
Snapped a picture of the Merrimack with the top off.
IMG_20190801_205857.jpg
 
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Dazza80 said:
So what does anyone think that hole is for between the tubes?
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No clue but I plugged mine. There are so many uncontrollable holes in this stove I don't get it. At this point I've probably reduced the uncontrollable air coming in to my stove, including secondary tubes, by 80% and it runs beautifully. I'm not at all surprised that out of the box this thing was a complete uncontrollable inferno. I just don't know what they were thinking.
 
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therealdbeau said:
No clue but I plugged mine. There are so many uncontrollable holes in this stove I don't get it. At this point I've probably reduced the uncontrollable air coming in to my stove, including secondary tubes, by 80% and it runs beautifully. I'm not at all surprised that out of the box this thing was a complete uncontrollable inferno. I just don't know what they were thinking.
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We have 5 customers using this stove and none have issues with control. Have you had your draft tested? Hove you had a pro go over the stove to make sure it is in proper working order? What file temps were you seeing before when it was un controlable?
 
therealdbeau said:
No clue but I plugged mine. There are so many uncontrollable holes in this stove I don't get it. At this point I've probably reduced the uncontrollable air coming in to my stove, including secondary tubes, by 80% and it runs beautifully. I'm not at all surprised that out of the box this thing was a complete uncontrollable inferno. I just don't know what they were thinking.
Click to expand...

Want to hear something funny/crazy/scary...
With the Montpelier 2 (doesn't look like they are making a 2020 compliant Merrimack) there are NO user adjustable air controls.

It's epa low-high output range is 24,000-27,000 btu an hour. In other words, it burns full blast all the time.

With how hot my Monty ran before the air mods that is truly a scary thought.

Although maybe it won't be quite such an issue. It's not based on the original Montpelier at all. It's a modified Voyager grand firebox (now that hearth and home owns quad and vc I guess they can do this), same dimensions as current voyageur grand, just with a Montpelier-looking facade. They are using the same firebox with a different facade as the new 2020 quad insert which is currently labeled the Expedition II
 
SculptureOfSound said:
Want to hear something funny/crazy/scary...
With the Montpelier 2 (doesn't look like they are making a 2020 compliant Merrimack) there are NO user adjustable air controls.

It's epa low-high output range is 24,000-27,000 btu an hour. In other words, it burns full blast all the time.

With how hot my Monty ran before the air mods that is truly a scary thought.

Although maybe it won't be quite such an issue. It's not based on the original Montpelier at all. It's a modified Voyager grand firebox (now that hearth and home owns quad and vc I guess they can do this), same dimensions as current voyageur grand, just with a Montpelier-looking facade. They are using the same firebox with a different facade as the new 2020 quad insert which is currently labeled the Expedition II
Click to expand...
 

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therealdbeau said:
I'm really not sure what, if any, difference it makes to block off the bottom air holes. I just can't tell a big enough difference either way to really make up my mind. Currently I have one side completely blocked and the other side about half blocked and I think I'll stick with that for now.

I'm overall very happy with this stove now after the mods. When I first got it I thought the 12 hours burn time in the brochure was a joke. I'd get 8 maybe 10 if I packed the stove really tight. After the mods, 12 hours seems easily achievable.
Click to expand...
I've been running the stove these last 2 weeks since winter came 2 months early. I done my tube mods and put about 70% blocked absolutely improved control and performance. I blocked both air intakes on the bottom of the stoves and I'm convinced it's for the worse-incomplete burns,less secondary and more black on the fire brick. Gonna stick with 1 doghouse air hole blocked and 1 open
 
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Dazza80 said:
I've been running the stove these last 2 weeks since winter came 2 months early. I done my tube mods and put about 70% blocked absolutely improved control and performance. I blocked both air intakes on the bottom of the stoves and I'm convinced it's for the worse-incomplete burns,less secondary and more black on the fire brick. Gonna stick with 1 doghouse air hole blocked and 1 open
Click to expand...

Thanks for the update. I've had them both blocked off for a bit now and kinda forgot about it but seeing your post I'm going to open one and see how things go.

You guys are going to think I'm crazy but the way the doghouse stuck out halfway into the firebox drove me crazy so I cut it off lol. Now that front ledge is just even all the way across. Much nicer loading up the firebox now.
 
Can someone take a picture and circle where the air intakes are on the bottom? I have a Merrimack, did the mod to the air tubes (which made the stove much much better), and now I'm curious as to how closing off the air intakes would work. But I can't for the life of me figure out where they are!

Sent from my Pixel 2 XL using Tapatalk
 
Just bought one of these have been running it for a week and I feel the same way that I wood is burning so fast in it. With the damper shut it seems like its roaring to me. Tonight is my first attempt at an overnight on it. I doubt I'd have much of a coal bed left in the am. Look great. Cost me 5000 with an insulated 2 story liner. I feel the stove cools of very fast. Just hope I made a good choice with this stove...
 
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