Vermont Castings Merrimack/Montpelier

[therealdbeau]

Vermont Castings Merrimack and Montpelier chat.

This thread started out as a question about the doghouse air jet but became more about mine and others specific VC stoves.

The first page or so is mostly responses to the original question.

 

[yooper08]

The inlet in the bottom is a primary air source. This is typically controlled with the air control.

 

[therealdbeau]

The inlet in the bottom is a primary air source. This is typically controlled with the air control.

The primary air source is at the top of the glass. It is controlled by the primary air control lever. I've taken the stove apart enough to know for certainty that the air inlet at the bottom is wide open all the time and not controllable.

 

[bholler]

The primary air source is at the top of the glass. It is controlled by the primary air control lever. I've taken the stove apart enough to know for certainty that the air inlet at the bottom is wide open all the time and not controllable.

What stove is this?

 

[begreen]

The primary air source is at the top of the glass. It is controlled by the primary air control lever. I've taken the stove apart enough to know for certainty that the air inlet at the bottom is wide open all the time and not controllable.

Sounds like the boost air but we need to know what stove make and model this is to check.

 

[Highbeam]

Most noncat stoves have one or more uncontrolled air inlets. Even the one that you can control is usually limited so that you can not close it all of the way. My noncat has four separate uncontrolled air inlets in addition to the one that is semi controlled by the air control lever.

Don't block them off, they are intentional for clean burning.

 

[bholler]

Most noncat stoves have one or more uncontrolled air inlets. Even the one that you can control is usually limited so that you can not close it all of the way. My noncat has four separate uncontrolled air inlets in addition to the one that is semi controlled by the air control lever.

Don't block them off, they are intentional for clean burning.

Cat stoves have some unlimited air as well for the same reasons

 

[therealdbeau]

The stove is a Vermont Castings Merrimack.

So a two part question I guess. What is it for and why is it where it is... I've seen some stoves have a bottom air jet but they are simply at the front of the bottom. On my stove it is built out almost half way into the firebox.

 

[begreen]

It sounds like boost air. If so, the purpose is for easier starting. If draft is strong it may not be necessary and blocking it off normally will not disrupt proper clean burning as long as this is all that is blocked. The location varies. Some Quads put it in the rear of the firebox.

FWIW, VC calls this the Primary air hole.

 

[yooper08]

Primary air sources are ones that feed the primary combustion area, not necessarily the main source of air. Agree it's probably a boost air, my stove has one as well, but it's essentially a tiny hole.

 

[therealdbeau]

Thanks for all the replies. Doesn't this system require an established fire to create the vacuum necessary to draw air into the firebox? In that case wouldn't it be useless for easier starting?

Not trying to be rude, just trying to understand. Thanks

 

[begreen]

It looks like a pretty small hole, the point is just to assist the fire. As long as there is draft, as soon as the door is closed a vacuum will be present in the firebox. In most cases this does not need a fire. Just the differential between the interior house temp and the exterior temp creates the draft. FWIW, my guess is that the majority of primary air is coming thru the air wash.

How did you block this air port?

 

[therealdbeau]

How did you block this air port?

There are two small holes on either side of the stove about 1/2" each that can be accessed from the front behind the bottom grate where the blower fan draws air. I placed magnets over these holes.

I was thinking about cutting off the "nose" of this boost intake to make the floor of the firebox more rectangular because it protrudes into the firebox making loading the stove a pain.

 

[Dazza80]

There are two small holes on either side of the stove about 1/2" each that can be accessed from the front behind the bottom grate where the blower fan draws air. I placed magnets over these holes.

I was thinking about cutting off the "nose" of this boost intake to make the floor of the firebox more rectangular because it protrudes into the firebox making loading the stove a pain.

 

[Dazza80]

So i have a merrimack and pretty new with stoves. Been reading on here and other places not a ton of info about these. but i will say i did monitor that "boost" air flow on the bottom of the stove and its enough air to blow right through an oak split. It never stops. Ive been putting a biobrick about 2 inches in front of it to help control the burn. I do think ill put some magnets over the holes like you did to see how that works. Dont know if youve noticed an issue with the air control lever when you push it all the way left to open the extra hole to get the fire going again after a reload. It doesnt always auto close all the way it has a small clip inside and it gets caught. It will stay open until you release it.
Its a pita

 

[therealdbeau]

So i have a merrimack and pretty new with stoves. Been reading on here and other places not a ton of info about these. but i will say i did monitor that "boost" air flow on the bottom of the stove and its enough air to blow right through an oak split. It never stops. Ive been putting a biobrick about 2 inches in front of it to help control the burn. I do think ill put some magnets over the holes like you did to see how that works. Dont know if youve noticed an issue with the air control lever when you push it all the way left to open the extra hole to get the fire going again after a reload. It doesnt always auto close all the way it has a small clip inside and it gets caught. It will stay open until you release it.
Its a pita

Its hard for me to really get a sense of if there is any meaningful difference with the boost air blocked off or not. Currently I do not have it blocked as I think it might have an effect on the strength the secondaries and maybe contributing to my flue connector area glowing recently.

So the secondary tubes and the boost air AKA doghouse are not user controllable and when the primary air is closed these two areas are pulling air in based on draft. I now think that whether you block the doghouse off or not the same amount of air is being pulled into the stove. The only difference being that with it blocked all the air is coming in through the secondary tubes.

Recently, on a couple occasions I saw, through the top grate,a slight glow coming from the flue connector area. I'm thinking this may have been from over active secondaries caused by blocking the doghouse air. Just a hunch though, i haven't been able to confirm this yet.

My point is I think the doghouse air inlet may function partly to balance out the secondaires.

Regarding that auto set-back reload air function, I have completely disabled it. Not only did mine break the first day (the wire snapped, I guess I pushed it too hard) I just didn't feel like it worked properly anyway. So I removed that box completely and just covered up the hole with a magnet. The whole thing seemed a little gimmicky. If i feel the fire needs a little boost of air I just crack the door open a little bit. What I do is unlock the doors and open the right door just enough and turn the handle so the door rests on the latch just cracked open.

Yeah the Merrimack doesn't get talked about much here but overall I think it's a good stove. It looks great with it's huge glass front. Let me know if you have any questions.

 

[SculptureOfSound]

I found when completely blocking the doghouse air (coupled with my tube air block mod) I'd more often get pieces of charcoal/unburnt wood in the morning.

I think the design of this air is quite similar on the Monty and Merrimack. What I'm doing now is completely blocking one hole with magnet and then blocking about 85% of the other hole. This allows a bit of air in and keeps it so the coals burn down, but it visibly slows the burn too (watch the flames or coals near the air holes when you cover it an uncover it. They will flicker much more when uncovered and also, if you have one of those wispy primary flames that is more like a secondary (wispy, more translucent and lots of blue) you will see with the doghouse air open this flame rises to the tubes noticeably faster. It makes sense that it would cause the smoke/gases to rise faster out of the wood as it is air from below the wood being pulled up due to the vacuum. Basically it changes the airflow pattern in the box.

The reason I leave one hole completely covered and one barely open is that I still see the air from the one hole coming out all three air jets in my firebox (both of the air feeder holes feed into the same air channel path so really only one is needed) and also it is easier to adjust if I want. Sometimes if I feel the fire needs a bit more air to sustain secondaries better (maybe a slightly wet piece of wood in the mix that load) and I can easily adjust just the one magnet.

Anyhow, I'm still experimenting with air mods on my Monty but I think I've hit close to the perfect set of mods just last night. I had coals after 7 hours with a half load of wood. Just 4 branches pieces (2 about 2.5 inches in diameter - so quite small-town and the other 2 about 4 to 4.5 in diameter). Some pine and some apple wood. So really not much wood, maybe half of what I could fit in total. I loaded it onto a medium bed of coals, had air completely closed with about 2 minutes. I had about 3 minutes of the coolest secondary show where the.box would go momentarily black and then huge aurora borealis like secondaries would erupt and swirl around the box. A very small primary flame emerged (maybe a 2 inch high lazy thing) and more secondaries that became constant. It picked up slowly but was at 500+ stove top soon within maybe 10 mins and slowly crawled to almost 700 stove top over 2 hours. The primary flame actually disappeared about 10 mins in and it was totally secondaries for over 45 mins, maybe over an hour.

I went to bed at that point...tons of heat already generated and it looked like there was a fair bit left in the wood. Then still some coals 7 hours later...and that was with the fan on absolute full blast all night (this only because my speed controller on the fan died earlier that night so the fan is either off or if on, at full speed).

I think I could have had coals at 10-12 hours with a full load of oak.

I'll go over my experiments in detail in a new thread. The short of it is 85% blocked doghouse air, about 40% blocked tube air (less blockage in the back tube, this then creates more of a vacuum at the back tube location and draws the secondaries gases towards the back of the firebox) and a "ghetto damper" which is just a steel foil flap that sits between front tube and baffle and extends the baffle length a bit and reduces the space between baffle and top of firebox thus acting as a damper

 

[Dazza80]

I found when completely blocking the doghouse air (coupled with my tube air block mod) I'd more often get pieces of charcoal/unburnt wood in the morning.

I think the design of this air is quite similar on the Monty and Merrimack. What I'm doing now is completely blocking one hole with magnet and then blocking about 85% of the other hole. This allows a bit of air in and keeps it so the coals burn down, but it visibly slows the burn too (watch the flames or coals near the air holes when you cover it an uncover it. They will flicker much more when uncovered and also, if you have one of those wispy primary flames that is more like a secondary (wispy, more translucent and lots of blue) you will see with the doghouse air open this flame rises to the tubes noticeably faster. It makes sense that it would cause the smoke/gases to rise faster out of the wood as it is air from below the wood being pulled up due to the vacuum. Basically it changes the airflow pattern in the box.

The reason I leave one hole completely covered and one barely open is that I still see the air from the one hole coming out all three air jets in my firebox (both of the air feeder holes feed into the same air channel path so really only one is needed) and also it is easier to adjust if I want. Sometimes if I feel the fire needs a bit more air to sustain secondaries better (maybe a slightly wet piece of wood in the mix that load) and I can easily adjust just the one magnet.

Anyhow, I'm still experimenting with air mods on my Monty but I think I've hit close to the perfect set of mods just last night. I had coals after 7 hours with a half load of wood. Just 4 branches pieces (2 about 2.5 inches in diameter - so quite small-town and the other 2 about 4 to 4.5 in diameter). Some pine and some apple wood. So really not much wood, maybe half of what I could fit in total. I loaded it onto a medium bed of coals, had air completely closed with about 2 minutes. I had about 3 minutes of the coolest secondary show where the.box would go momentarily black and then huge aurora borealis like secondaries would erupt and swirl around the box. A very small primary flame emerged (maybe a 2 inch high lazy thing) and more secondaries that became constant. It picked up slowly but was at 500+ stove top soon within maybe 10 mins and slowly crawled to almost 700 stove top over 2 hours. The primary flame actually disappeared about 10 mins in and it was totally secondaries for over 45 mins, maybe over an hour.

I went to bed at that point...tons of heat already generated and it looked like there was a fair bit left in the wood. Then still some coals 7 hours later...and that was with the fan on absolute full blast all night (this only because my speed controller on the fan died earlier that night so the fan is either off or if on, at full speed).

I think I could have had coals at 10-12 hours with a full load of oak.

I'll go over my experiments in detail in a new thread. The short of it is 85% blocked doghouse air, about 40% blocked tube air (less blockage in the back tube, this then creates more of a vacuum at the back tube location and draws the secondaries gases towards the back of the firebox) and a "ghetto damper" which is just a steel foil flap that sits between front tube and baffle and extends the baffle length a bit and reduces the space between baffle and top of firebox thus acting as a damper

Experimenting today with the magnets over both doghouse holes on the merrimack. With both covered its hard to get the fire going opened the door a bit moved magnets around all kinds of tinkering but ended up taking the one by the fan contol off and slide the other one over to close the hole after the fire got going seems to work already getting longer burn on first fire.. Where on the merrimack do you take the temps? Only time i ever get close to 700 is on the doors the ledge on the merrimack usually sits around 200

 

[therealdbeau]

Experimenting today with the magnets over both doghouse holes on the merrimack. With both covered its hard to get the fire going opened the door a bit moved magnets around all kinds of tinkering but ended up taking the one by the fan contol off and slide the other one over to close the hole after the fire got going seems to work already getting longer burn on first fire.. Where on the merrimack do you take the temps? Only time i ever get close to 700 is on the doors the ledge on the merrimack usually sits around 200

Ahh yes the great conundrum of the Merrimack, where to read temps, who can say.

I just point my IR thermo at the metal in the middle of the glass to get and idea. I kinda gave up on worrying about the temperature unless it looks like things are getting out of control.

The worst I've seen is a slight glow coming from the flue connector area if you look through the top grate and usually this is accompanied by the deflector at the top of the firebox also slightly glowing. At the point I read the front glass area around 750 or so.

 

[Dazza80]

Ahh yes the great conundrum of the Merrimack, where to read temps, who can say.

I just point my IR thermo at the metal in the middle of the glass to get and idea. I kinda gave up on worrying about the temperature unless it looks like things are getting out of control.

The worst I've seen is a slight glow coming from the flue connector area if you look through the top grate and usually this is accompanied by the deflector at the top of the firebox also slightly glowing. At the point I read the front glass area around 750 or so.

Yes the temps are all over the board. I do the same ir thermo at the center of both doors had it at 700 only once but im using wood thats not well seasoned so hopfully this year ill get better wood for the burn season and get better temps. Ive only had it 6 weeks so lots to learn

 

[therealdbeau]

Yes the temps are all over the board. I do the same ir thermo at the center of both doors had it at 700 only once but im using wood thats not well seasoned so hopfully this year ill get better wood for the burn season and get better temps. Ive only had it 6 weeks so lots to learn

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.

 

[Dazza80]

Quote from SculptureOfSound "The reason I leave one hole completely covered and one barely open is that I still see the air from the one hole coming out all three air jets in my firebox (both of the air feeder holes feed into the same air channel path so really only one is needed) and also it is easier to adjust if I want. Sometimes if I feel the fire needs a bit more air to sustain secondaries better (maybe a slightly wet piece of wood in the mix that load) and I can easily adjust just the one magnet."
So i done this today both holes open(magnets to the side) on the doghouse, air control fully left with that gimmick box disconnected solid bed of coal pulled to the front and loaded 6 descent size spilts tight in the back leveled the coals down put one pellet brick on top of the coals to get the flames going and one more split on the brick. Left the door cracked for 5 minutes or so to get it going closed the door after 30 minutes i covered one hole with the magnet then gradually closed the air control down. Got a pretty good light show with the secondary lasted a good while. Doors have been steady about 425f for 4 hours now and still have 3 full splits untouched in the back its longest burn ive gotten. The wood isnt seasoned to good so im hoping for higher temps when i get better wood i have to buy it so still searching for a good source at a descent price

 

[Dazza80]

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.

Nice fire you have going
This one is going 4 1/2 hrs

 

[Dazza80]

Glass is all dirty i was loading it NS today experimenting

 

[therealdbeau]

I usually load N/S at night before bed because I don't like the idea of logs rolling into the glass but when I'm around to watch it I go E/W.

The dirty glass is surely because of not completely dry wood. I had the same issue when I first got the stove because I didn't have nice dry wood. You mentioned pellet blocks. I found if I set the pellet blocks right along the front andrion it helps keep the glass cleaner.