Vermont Castings Merrimack/Montpelier

[therealdbeau]

I changed the name of the thread because it seems to have turned into a Merrimack discussion which is cool

 

[SculptureOfSound]

Sorry if I wasn't clear, I've got the VC Montpelier not a Merrimack, but seems like a lot of the design is the same.

On the Montpelier, at least with the surround off, you can get a true stove top temp as there is a portion of the top not covered by the convective jacket. I found that the temp I get with the IR gun into the air vent (targeting a specific spot that gets hottest) is about 150 cooler than the hottest part of the stove top, so that is how I estimate my stove top temps now that I have the surround on. For the first month or so I ran without the surround to get true stove top temps and compare.

Here's a pic of the top of the Montpelier with the sheet metal shell off. The metal shell is a "U" shape which covers the left and right channels and a portion of the front, however the area in front of the flue collar (and the little area on the sides and behind it) is always exposed so you can get the real stove top temp there.

 

[therealdbeau]

Sorry if I wasn't clear, I've got the VC Montpelier not a Merrimack, but seems like a lot of the design is the same.

On the Montpelier, at least with the surround off, you can get a true stove top temp as there is a portion of the top not covered by the convective jacket. I found that the temp I get with the IR gun into the air vent (targeting a specific spot that gets hottest) is about 150 cooler than the hottest part of the stove top, so that is how I estimate my stove top temps now that I have the surround on. For the first month or so I ran without the surround to get true stove top temps and compare.

Here's a pic of the top of the Montpelier with the sheet metal shell off. The metal shell is a "U" shape which covers the left and right channels and a portion of the front, however the area in front of the flue collar (and the little area on the sides and behind it) is always exposed so you can get the real stove top temp there. View attachment 241016

No problem at all. I knew you had the Montpelier anyway. They are very similar stoves. The Merrimack just has a couple extra features that I personally think are not very well implemented.

I might have to try out your secondary tubes blocking mod. Did you just take the tubes out and cram the foil in there and put them back on?

 

[Dazza80]

No problem at all. I knew you had the Montpelier anyway. They are very similar stoves. The Merrimack just has a couple extra features that I personally think are not very well implemented.

I might have to try out your secondary tubes blocking mod. Did you just take the tubes out and cram the foil in there and put them back on?

Not to worry. I also think these stoves have a lot of similarities and with a few tweaks it has potential

 

[SculptureOfSound]

Does the Merrimack have an exposed stove top area too?

 

[SculptureOfSound]

No problem at all. I knew you had the Montpelier anyway. They are very similar stoves. The Merrimack just has a couple extra features that I personally think are not very well implemented.

I might have to try out your secondary tubes blocking mod. Did you just take the tubes out and cram the foil in there and put them back on?

Pretty much. A few thoughts...

I obviously cant advocate these kinds of mods.

If you do make any mods safety first. Be sure to have smoke alarms and especially CO alarms throughout the house.

Don't use aluminum foil. I think it will melt at the temps it will see.

I used steel foil I had on hand - not a common thing and not cheap but what is nice is it let me experiment with blocking off different amounts of air. Originally I had them heavily blocked - this causes two problems...much harder starts and harder to get a clean burn in the early burn phase.

I now have them maybe 50% blocked and it works quite well. Starts are still more difficult and require more time with the door cracked open, but the stove is more controllable now. It still climbs to 600 or 650 quite often but it does so burning less wood more slowly and with more residence time of the air in the box. I also find the glass stays cleaner as the flames (and thus air) don't shoot so hard into the glass...prior to the mod it would look like a dragon breathing fire towards the glass on with a full load of wood fully choked down.

The ideal solution would be a damper and I'm going to look into that next year, but for now this works decently. More burn time with the same or greater heat (greater total heat for sure). It's not perfect as messing with the ratio of primary to secondary air is what is making the starts and early burn more difficult, but it's better than a run away stove.

Oh, and I found that leaving the back tube the least blocked seems to work best. More air is drawn in at the back tube then creating a vacuum back there and pulling the flames back a bit, keeping them in the box longer.

I'd say rough numbers might be
1st tube 75% blocked
2nd tube 60%
3rd 50%
4th (back) 40%

 

[Dazza80]

Pretty much. A few thoughts...

I obviously cant advocate these kinds of mods.

If you do make any mods safety first. Be sure to have smoke alarms and especially CO alarms throughout the house.

Don't use aluminum foil. I think it will melt at the temps it will see.

I used steel foil I had on hand - not a common thing and not cheap but what is nice is it let me experiment with blocking off different amounts of air. Originally I had them heavily blocked - this causes two problems...much harder starts and harder to get a clean burn in the early burn phase.

I now have them maybe 50% blocked and it works quite well. Starts are still more difficult and require more time with the door cracked open, but the stove is more controllable now. It still climbs to 600 or 650 quite often but it does so burning less wood more slowly and with more residence time of the air in the box. I also find the glass stays cleaner as the flames (and thus air) don't shoot so hard into the glass...prior to the mod it would look like a dragon breathing fire towards the glass on with a full load of wood fully choked down.

The ideal solution would be a damper and I'm going to look into that next year, but for now this works decently. More burn time with the same or greater heat (greater total heat for sure). It's not perfect as messing with the ratio of primary to secondary air is what is making the starts and early burn more difficult, but it's better than a run away stove.

Oh, and I found that leaving the back tube the least blocked seems to work best. More air is drawn in at the back tube then creating a vacuum back there and pulling the flames back a bit, keeping them in the box longer.

I'd say rough numbers might be
1st tube 75% blocked
2nd tube 60%
3rd 50%
4th (back) 40%

Thanks for all the info .. I have noticed any thing i do with the air affects the first fire and reloads.. Burned a lot of wood before i realized the fire start assist/Air control was getting stuck open and i was loading every 2hrs

 

[therealdbeau]

Does the Merrimack have an exposed stove top area too?

No not really. Maybe if you partially disassemble it by taking the top shelf and top lattice off you could get a good shot at the stove top.

 

[therealdbeau]

@Dazza80 Quick question. Does your air control handle move fairly effortlessly or is there a good bit or resistance moving the lever left/right?

 

[therealdbeau]

@SculptureOfSound hey does your Montpelier have a small hole on the top right side along the channel that feeds the secondaries right before the second tube?

I just noticed this tonight while experimenting with limiting the secondaries. I'm going to block it off tomorrow. It looks like VC had to go above and beyond to get this thing to pass EPA lol.

Have you seen this article?... http://www.gulland.ca/florida_bungalow_syndrome.htm

I modded my secondaries tonight, reduced them down to about 50% and it went really well. Not quite enough though I think for me. I'm going to close them off a little bit more tomorrow and I think it'll be near perfect. I'll write it all up with pics tomorrow.

 

[SculptureOfSound]

Just checked before starting today's fire and I didn't see any such hole. Must be the Merrimack needed more air likely due to the larger firebox.

Can't wait to hear and see your results. I monkeyed with the foil in the tubes about 3 or 4 times and it is finally "just right".

As an example...
not sure what I was burning last night (some of the wood was here when we bought the house). I burned all day yesterday...almost all pine all day long on 4-5 hour reloads (kept the house at 76 with outside temp of 30). Last load of the night (I'm not going for overnight burns due to lack of enough hardwood) I put in about a half load...it was A split of pine and a split and branch of some hardwood. I had coals 12 hours later buried in the ash. At 8 hours stove top was still about 150-170. Not bad for a small load of not all hardwood!

Prior to the mod I got a bit more heat in the first hour or two of a reload (not much, most was going up the chimney), but would need to reload about 30-50% sooner than I do now

 

[SculptureOfSound]

I did see that article in the year-plus I researched prior to getting my insert. Still, with a chimney of only 13' (firebox floor to top of clay flue) and reports that the Montpelier was a hard breather - not to mention my previously very smoky open chimney, I was really worried I'd have the opposite problem of smoke in the house.

I did extend my liner by an additional 4' so it's now 17 from floor to top (or 15' from top of appliance) but I still never would have guessed that would lead to overdraft.

I'm not even sure it is an overdraft or if the design of these just allows too much air into the secondaries. I don't get any smoke rollout when I open the door (if I'm careful and don't open too quickly) and the flames really did flicker like mad prior to the mod even with the air fully closed (the flickering was caused by the secondary air not the primary...there's almost no primary air with the lever all the way closed, as I've been able to confirm post modification).

Maybe it's because the top of my chimney is so much taller than the peak of my roof? Maybe because we have very few ceiling light fixtures? I dunno. All I know is once you get the secondary balance right start ups are not much harder, the burn is slower (but once established I still can't kill it completely with air fully closed, this is ok imo, as stove top peaks around 700 max) , yet the combustion is still complete...no charcoal left in the morning. Hear output over the course of the burn goes way up as does burn time (especially coaling time)

 

[Dazza80]

@Dazza80 Quick question. Does your air control handle move fairly effortlessly or is there a good bit or resistance moving the lever left/right?

It moves pretty easy with a little resistance i not much.i was looking at it and the spring could probably be removed and modified since its used to help with air assist thats disengaged

 

[Dazza80]

@SculptureOfSound hey does your Montpelier have a small hole on the top right side along the channel that feeds the secondaries right before the second tube?

I just noticed this tonight while experimenting with limiting the secondaries. I'm going to block it off tomorrow. It looks like VC had to go above and beyond to get this thing to pass EPA lol.

Have you seen this article?... http://www.gulland.ca/florida_bungalow_syndrome.htm

I modded my secondaries tonight, reduced them down to about 50% and it went really well. Not quite enough though I think for me. I'm going to close them off a little bit more tomorrow and I think it'll be near perfect. I'll write it all up with pics tomorrow.

Some pictures would be great im not sure how to go about modding the secondaries yet

 

[SpaceBus]

You can't get a meaningful reading from the top of the stove because unlike other stoves there is a substantial space there that the blower send the air out through.

A lot of what you read on the forum here about other people's stoves I think don't apply to us because of the design of the Merrimack. For example "stove top temp" doesn't apply to us. That said, while other stoves may have less quirks and more traditional operation, we get to enjoy an absolutely beautiful view rivaled only by an open fireplace. Of my friends that have stoves, when they come over their wives say why didn't we get that one.

Oh and by the way, dry wood is the real difference maker. Once you have good dry wood you'll love it.

Wow, that is a cool stove.

 

[SculptureOfSound]

You guys ever get these detached blue secondaries in the Merrimack? Just curious if it burns similar to the Monty. This is a medium load of wood, about 75% pine, air turned down early after the reload. Stove top is about 500-550 where it will cruise for some time
(Ignore the fan noise, my speed controller went on me so now the fan only runs at full speed)

 

[therealdbeau]

@Dazza80 hey do you think you could take a picture of the air control mechanism behind the top lattice? I think there is something wrong with mine and I'd like to see yours to compare.

You guys ever get these detached blue secondaries in the Merrimack? Just curious if it burns similar to the Monty. This is a medium load of wood, about 75% pine, air turned down early after the reload. Stove top is about 500-550 where it will cruise for some time
(Ignore the fan noise, my speed controller went on me so now the fan only runs at full speed)

Yes I do get this kind of "ghost" secondary action. It's really fun to watch.

 

[Dazza80]

@Dazza80 hey do you think you could take a picture of the air control mechanism behind the top lattice? I think there is something wrong with mine and I'd like to see yours to compare.



Yes I do get this kind of "ghost" secondary action. It's really fun to watch.

 

[Dazza80]

@Dazza80 hey do you think you could take a picture of the air control mechanism behind the top lattice? I think there is something wrong with mine and I'd like to see yours to compare.



Yes I do get this kind of "ghost" secondary action. It's really fun to watch.

@Dazza80 hey do you think you could take a picture of the air control mechanism behind the top lattice? I think there is something wrong with mine and I'd like to see yours to compare.



Yes I do get this kind of "ghost" secondary action. It's really fun to watch.

Not sure if thats what you want?

 

[therealdbeau]

Yes perfect thank you!

As for modding the secondaries I did it like this...

I bought a 1/2 inch baffle board and used the secondary tubes to cut into the baffle board effectively blocking the tubes then I drilled a 1/4 hole through the ends.

It has made a difference for sure. I'm still playing with it. The baffle board is a bit fragile though so I don't know how it will hold up over time. I might try to find something like metal washers to use instead.

 

[Dazza80]

Yes perfect thank you!

As for modding the secondaries I did it like this...

I bought a 1/2 inch baffle board and used the secondary tubes to cut into the baffle board effectively blocking the tubes then I drilled a 1/4 hole through the ends.

It has made a difference for sure. I'm still playing with it. The baffle board is a bit fragile though so I don't know how it will hold up over time. I might try to find something like metal washers to use instead.

So whats the main difference with the baffles modified? Just longer burn time.. I have a 30ft chimney so absolutely no draft issues.. We had 45 to 55mph winds today so i watched a little closer today. Stove ran great got loads of secondary and the heat was cranking. Im not sure if it was drafting stronger and pulling more air through the tubes

 

[therealdbeau]

So whats the main difference with the baffles modified? Just longer burn time.. I have a 30ft chimney so absolutely no draft issues.. We had 45 to 55mph winds today so i watched a little closer today. Stove ran great got loads of secondary and the heat was cranking. Im not sure if it was drafting stronger and pulling more air through the tubes

So for me on a full load even with the air control all the way closed the stove would run too hot. Flames would shoot out of the secondaries like blow torches and the flue connector area would glow a little bit. And my chimney is only 17ft or so and it's not terribly cold here so my draft shouldn't be excessive.

 

[Dazza80]

So for me on a full load even with the air control all the way closed the stove would run too hot. Flames would shoot out of the secondaries like blow torches and the flue connector area would glow a little bit. And my chimney is only 17ft or so and it's not terribly cold here so my draft shouldn't be excessive.

Okay i think my poorly seasoned wood is preventing the excessive heat.. But my secondary was firing pretty crazy today center of the doors were 725degrees

 

[SculptureOfSound]

Yes perfect thank you!

As for modding the secondaries I did it like this...

I bought a 1/2 inch baffle board and used the secondary tubes to cut into the baffle board effectively blocking the tubes then I drilled a 1/4 hole through the ends.

It has made a difference for sure. I'm still playing with it. The baffle board is a bit fragile though so I don't know how it will hold up over time. I might try to find something like metal washers to use instead.

That's an interesting approach - smart! Beats my ghetto foil balls since you can actually determine exact volume reduction.

I do wonder though if the foil does have a couple advantages though. It's a misshapen crumple so adds turbulence to the air passing by. Also, it's thin metal and so heats up very quickly and thus should result in some greater degree of pre heating of the air, especially with the added turbulence/slowing.

Although probably not a big deal either way. 95% of the preheating should happen before it enters the tubes. On the Monty it runs along the side in a small chamber that is insulated on the outside and zig zags past some cast baffles.

 

[SculptureOfSound]

did you ever find the right amount of blockage - curious how much that was