If your VC Merrimack uses too much wood

[WoodyIsGoody]

My point is that they are making some unreasonable requirements, to comply, stove manufacturers do what they must. For now, that means giving the customer less control over the appliance.

Man, judging by the asinine things I've seen people do when heating with wood over the last several decades, it's probably a good thing to make wood burning appliances more foolproof!

Now if they could just figure out a way to prevent users from putting uncured splits into the firebox!

 

[EatenByLimestone]

*cough* pellet*cough*

 

[webby3650]

The manufacturers are not "reverting back" to standing flame pilots - they never quit making them! Yes, they cost a little less - just as a carbureted engine costs slightly less than EFI engine.

But if you think I'm "living under a rock" when I say IPI is more reliable than the old standing flame pilot, then you must think HVAC industry pro's who work with gas appliances day in/day out must be naïve as well:

http://hvac-talk.com/vbb/showthread.php?187567-intermittent-vs-standing-pilot

HVAC industry pro "Hearthman" shares his experience in post #2. Yes, overall IPI ignition is more reliable. Standing flame pilot lights have had more than their share of lemons and are the number one cause of service calls on gas appliances with pilots. I don't know of anyone with extensive gas appliance experience who believes otherwise.

Extensive gas appliance knowledge is different than extensive fireplace knowledge. IPI in fireplaces have issues that are not shared with other appliances. Don't know why they can't seem to get these "bugs" worked out. And yes, several manufacturers did quit using standing pilot units, and now offer standing pilot again. Sure standing pilot units are a bigger service call generator, there's about 20 to 1 out there in operation..we have a few IPI units out there that don't really have any issues, but we have some from various manufacturers that are plagued with problems. Constant revisions! Again, the HVAC industry does not see even a small fraction of the units that we who install and service fireplaces every single day.

 

[Easy Livin’ 3000]

Thanks for all your replies.

@jetsam - you hit it on the head: in my opinion the Merrimack is in your first category - an EPA emissions solution slammed on as an afterthought. Disappointingly so from VC, ruining an otherwise fine and beautiful insert.

@moresnow - exactly the same problem as you describe, my "fix" for the Merrimack is the same as yours by closing up the secondary air.

@ED 3000 - glass stays clean, sometimes a bit of white ash coating in the morning but that burns off with when the new batch of wood gets going. In the cold spell recently with temps around 15-F daytime, we turned off the geothermal heat pumps (they don't work well in that cold) and relied purely on the Merrimack in the living room and a Winterwarm in the basement to heat a drafty 3400 sq ft old stone house for 5 days straight. The glass was a bit glossed over after a week but cleaner than the Winterwarm which gets sooty in a day no matter what.

@EatenByLimestone - can't say at this time, we have it cleaned out every 2 years and have not done so since the fix of 2015 (due now). I don't expect a difference because it runs just as hot as before. I can't measure flue temp easily, not accessible.

@webby3650 and in general on this thread:

The primary air opening size is 2 square inches, damping it down closes this almost entirely, perhaps 1/2 sq inch open. The two secondary air openings on the other hand are about 3 square inches each with no ability to choke it down. (I'm going from memory about sizes when I had the thing apart, but the ratio is what matters, secondary about 3 times primary. And no control.)

Before the fix, it made NO difference when you close off the primary all the way. If it made a difference it was so small that you could not tell watching it for minutes before and after. Two cubic feet of fuel would be gone in 4 hours. I believed and proved that was on account of the secondary intakes that remained fully open.

After blanking off the secondary intakes, now when we close the primary it does exactly what you expect - within seconds the flames settle with a steady swirl like any other good firebox. Open it up and within seconds the fire responds.

So we are burning 1/4 the firewood simply because it is not wasting it up the chimney in uncontrollable flames. In my opinion, overall emissions is lower as I tried to explain at the onset.

Just measured the steady but small fires now which has been going since this morning, the Merrimack at 550-F, the Winterwarm at 600. They will idle along like this all day long with two small feeds each, then a large load at bedtime. Huge difference since castration.

I wonder how the glass stays clean without the overhead airwash from the secondaries. I'm tempted to try this myself, only the baffle is held up in my insert by the tubes!

 

[WoodyIsGoody]

Extensive gas appliance knowledge is different than extensive fireplace knowledge.

A gas fireplace IS a gas appliance. And the pro (Hearthman) who claimed IPI has better reliability than standing flame pilots WAS speaking to gas fireplaces! He doesn't use the alias "Hearthman" for no reason. So, you two have differing opinions. My experience and opinion aligns with Hearthman. Personally, I turn off my standing pilot in my gas fireplace when the heating season is over to avoid over-heating the room during summer. But I hate the way it blows out during strong winds. The pros who installed it say there is nothing they can do about that - just one of the downsides of standing flame pilots.

IPI in fireplaces have issues that are not shared with other appliances. Don't know why they can't seem to get these "bugs" worked out. And yes, several manufacturers did quit using standing pilot units, and now offer standing pilot again.

Well, that would be a faulty design, not an indication that IPI is inherently unreliable.

Sure standing pilot units are a bigger service call generator, there's about 20 to 1 out there in operation..we have a few IPI units out there that don't really have any issues, but we have some from various manufacturers that are plagued with problems.

Actually, no, I was saying that the standing flame pilot was (by far) the biggest service call generator of appliances with standing flame pilots (ignoring all IPI units). Standing flame pilots are notorious for reliability issues even though the basic technology has been around for many decades. IPI is inherently more reliable. That doesn't mean a bad engineer couldn't design an unreliable IPI unit! Plenty of bad engineers around.

 

[Shrek Ogre]

I can't tell from the layout how the secondaries might impact air turbulence and convection, but this I do know - most if not all of the secondaries feed to tubes at the top, igniting the gases as it leads into the flue. Closing off the input channel has not impacted its ability to keep the glass clean one iota. That gives credence to the premise that the secondary burn was added as an add-on for EPA compliance without much regard for consequence. They got the sticker.

 

[webby3650]

A gas fireplace IS a gas appliance. And the pro (Hearthman) who claimed IPI has better reliability than standing flame pilots WAS speaking to gas fireplaces! He doesn't use the alias "Hearthman" for no reason. So, you two have differing opinions. My experience and opinion aligns with Hearthman. Personally, I turn off my standing pilot in my gas fireplace when the heating season is over to avoid over-heating the room during summer. But I hate the way it blows out during strong winds. The pros who installed it say there is nothing they can do about that - just one of the downsides of standing flame pilots.



Well, that would be a faulty design, not an indication that IPI is inherently unreliable.



Actually, no, I was saying that the standing flame pilot was (by far) the biggest service call generator of appliances with standing flame pilots (ignoring all IPI units). Standing flame pilots are notorious for reliability issues even though the basic technology has been around for many decades. IPI is inherently more reliable. That doesn't mean a bad engineer couldn't design an unreliable IPI unit! Plenty of bad engineers around.

You can believe this if you want, that's fine. The reality is quit the opposition though.

 

[WoodyIsGoody]

The reality is quit the opposition though.

Finally we agree!

 

[WoodyIsGoody]

I can't tell from the layout how the secondaries might impact air turbulence and convection, but this I do know - most if not all of the secondaries feed to tubes at the top, igniting the gases as it leads into the flue. Closing off the input channel has not impacted its ability to keep the glass clean one iota. That gives credence to the premise that the secondary burn was added as an add-on for EPA compliance without much regard for consequence. They got the sticker.

I know on my early (1988) EPA tube stove the glass air wash air IS the primary air (all of it). I would expect most stoves likely use primary air to wash the glass since that air is headed directly to the bottom of the firebox.

 

[begreen]

I wonder how the glass stays clean without the overhead airwash from the secondaries. I'm tempted to try this myself, only the baffle is held up in my insert by the tubes!

The secondaries don't provide airwash for the glass. That usually is supplied via the primary air or independently on some stoves.

 

[webby3650]

Finally we agree!

So you evidently work in the hearth industry, primarily with gas fireplaces. Wood also? Do you have any experience with this Vermont Castings Merrimack? We dropped VC a few years back completely, so I've never had my hands on a Merrimack. It sounds like one that is in need of babysitting or modification to be usable.

 

[WoodyIsGoody]

So you evidently work in the hearth industry, primarily with gas fireplaces. Wood also? Do you have any experience with this Vermont Castings Merrimack? We dropped VC a few years back completely, so I've never had my hands on a Merrimack. It sounds like one that is in need of babysitting or modification to be usable.

Sounds like bad engineering.

My wife bought a plastic bucket with a rectangular shape. If you filled it halfway with about 5 quarts of water and picked it up by the steel wire handle all the water would run to one side and most of it would dump out. Defective design.

Doesn't mean that plastic buckets with steel wire handles are to blame. It's just a flawed implementation.

 

[begreen]

There are some decent reports for this insert. Some seem quite happy with it. I note that it has a start up air control. Wondering if this is being used properly or if it's stuck open?

 

[Shrek Ogre]

We initially thought that it might be the start-up air control. Our vendor inspected the mechanism, it was fine but they replaced it nonetheless. It was not it though. It's the afterburner add-on for (presumably) EPA purposes that was the negative factor. With the air intakes plugged, we very much love our Merrimack.

 

[Easy Livin’ 3000]

The secondaries don't provide airwash for the glass. That usually is supplied via the primary air or independently on some stoves.

My stove has 4 stainless pipes that hold the baffle up. They have progressively more holes the further forward you go, and they tilt downward more as well, the last (closest to the glass), point right at the glass. I guess I thought that was the airwash. What am I missing?

 

[begreen]

That last tube is to inject air right before the smoke path turns around the baffle. Most secondary burn systems are set up like this. I don't have a Flame or Osburn in front of me. Check for a channel right inside the door opening. Is there a deflector there? If so, that's the air wash.

 

[Easy Livin’ 3000]

That last tube is to inject air right before the smoke path turns around the baffle. Most secondary burn systems are set up like this. I don't have a Flame or Osburn in front of me. Check for a channel right inside the door opening. Is there a deflector there? If so, that's the air wash.

Yes, indeed there is a deflector right above the door. I never realized how simple this was. Makes me want to figure out how to retrofit something for our old VC Resolutes. Dirty glass is my only complaint on that stove.

 

[begreen]

Yes, indeed there is a deflector right above the door. I never realized how simple this was. Makes me want to figure out how to retrofit something for our old VC Resolutes. Dirty glass is my only complaint on that stove.

The original Resolute was a fine stove. I really enjoyed it, but I would be leary at this kind of mod for that stove.Introducing air via a supply, distribution manifold and deflecting vane would be very difficult. The air intake is in the rear bottom of the stove. It's why I ordered ours without the glass.

 

[Easy Livin’ 3000]

The original Resolute was a fine stove. I really enjoyed it, but I would be leary at this kind of mod for that stove.Introducing air via a supply, distribution manifold and deflecting vane would be very difficult. The air intake is in the rear bottom of the stove. It's why I ordered ours without the glass.

I am amazed by your level of knowledge about this stuff. Another pipe dream bites the dust! All for the best, really the last thing I needed was another project...

 

[begreen]

Loved the Resolute. It was a great stove and really good looking.

 

[Vic Santoro]

Thanks for all your replies.

@jetsam - you hit it on the head: in my opinion the Merrimack is in your first category - an EPA emissions solution slammed on as an afterthought. Disappointingly so from VC, ruining an otherwise fine and beautiful insert.

@moresnow - exactly the same problem as you describe, my "fix" for the Merrimack is the same as yours by closing up the secondary air.

@ED 3000 - glass stays clean, sometimes a bit of white ash coating in the morning but that burns off with when the new batch of wood gets going. In the cold spell recently with temps around 15-F daytime, we turned off the geothermal heat pumps (they don't work well in that cold) and relied purely on the Merrimack in the living room and a Winterwarm in the basement to heat a drafty 3400 sq ft old stone house for 5 days straight. The glass was a bit glossed over after a week but cleaner than the Winterwarm which gets sooty in a day no matter what.

@EatenByLimestone - can't say at this time, we have it cleaned out every 2 years and have not done so since the fix of 2015 (due now). I don't expect a difference because it runs just as hot as before. I can't measure flue temp easily, not accessible.

@webby3650 and in general on this thread:

The primary air opening size is 2 square inches, damping it down closes this almost entirely, perhaps 1/2 sq inch open. The two secondary air openings on the other hand are about 3 square inches each with no ability to choke it down. (I'm going from memory about sizes when I had the thing apart, but the ratio is what matters, secondary about 3 times primary. And no control.)

Before the fix, it made NO difference when you close off the primary all the way. If it made a difference it was so small that you could not tell watching it for minutes before and after. Two cubic feet of fuel would be gone in 4 hours. I believed and proved that was on account of the secondary intakes that remained fully open.

After blanking off the secondary intakes, now when we close the primary it does exactly what you expect - within seconds the flames settle with a steady swirl like any other good firebox. Open it up and within seconds the fire responds.

So we are burning 1/4 the firewood simply because it is not wasting it up the chimney in uncontrollable flames. In my opinion, overall emissions is lower as I tried to explain at the onset.

Just measured the steady but small fires now which has been going since this morning, the Merrimack at 550-F, the Winterwarm at 600. They will idle along like this all day long with two small feeds each, then a large load at bedtime. Huge difference since castration.

Thanks for all your replies.

@jetsam - you hit it on the head: in my opinion the Merrimack is in your first category - an EPA emissions solution slammed on as an afterthought. Disappointingly so from VC, ruining an otherwise fine and beautiful insert.

@moresnow - exactly the same problem as you describe, my "fix" for the Merrimack is the same as yours by closing up the secondary air.

@ED 3000 - glass stays clean, sometimes a bit of white ash coating in the morning but that burns off with when the new batch of wood gets going. In the cold spell recently with temps around 15-F daytime, we turned off the geothermal heat pumps (they don't work well in that cold) and relied purely on the Merrimack in the living room and a Winterwarm in the basement to heat a drafty 3400 sq ft old stone house for 5 days straight. The glass was a bit glossed over after a week but cleaner than the Winterwarm which gets sooty in a day no matter what.

@EatenByLimestone - can't say at this time, we have it cleaned out every 2 years and have not done so since the fix of 2015 (due now). I don't expect a difference because it runs just as hot as before. I can't measure flue temp easily, not accessible.

@webby3650 and in general on this thread:

The primary air opening size is 2 square inches, damping it down closes this almost entirely, perhaps 1/2 sq inch open. The two secondary air openings on the other hand are about 3 square inches each with no ability to choke it down. (I'm going from memory about sizes when I had the thing apart, but the ratio is what matters, secondary about 3 times primary. And no control.)

Before the fix, it made NO difference when you close off the primary all the way. If it made a difference it was so small that you could not tell watching it for minutes before and after. Two cubic feet of fuel would be gone in 4 hours. I believed and proved that was on account of the secondary intakes that remained fully open.

After blanking off the secondary intakes, now when we close the primary it does exactly what you expect - within seconds the flames settle with a steady swirl like any other good firebox. Open it up and within seconds the fire responds.

So we are burning 1/4 the firewood simply because it is not wasting it up the chimney in uncontrollable flames. In my opinion, overall emissions is lower as I tried to explain at the onset.

Just measured the steady but small fires now which has been going since this morning, the Merrimack at 550-F, the Winterwarm at 600. They will idle along like this all day long with two small feeds each, then a large load at bedtime. Huge difference since castration.

Where Do You block off the Secondary Intakes

 

[dkrupa]

yes, where and how did you close off the secondary air (I'm burning way too much wood)

 

[Shrek Ogre]

Here is how you take the secondary air tubes out of action. It takes an hour or two. You can possibly do this without moving your Merrimack and without disconnecting the flue, but it will be easier if you can move it forward for clearance or disconnect the flue and slide it out half-way for easier access.

Clarification: there are two versions of the Merrimack user manual. The current manual has been modified so that the components I wish to point out are no longer named or numbered. The older manual has them identified. It will be easier if you could use the older manual though it is easy enough even without.

New parts manual: Google "VC Merrimac parts manual" then navigate to it at Vermont Castings, or use this link: https://downloads.hearthnhome.com/serviceParts/MERRICB.pdf.

Older parts manual: I found a version at

Replacement Parts - Vermont Castings Merrimack Installation And Operating Manual [Page 17]

Vermont Castings Merrimack Manual Online: Replacement Parts. 73 MHSC reserves the right to make changes in design, materials, specifications, prices and discontinue colors and products at any time, without notice. Merrimack Large Insert Ref. Description part Number...

www.manualslib.com

Watch what you click in those pages, lots of advertising. You can find that manual with the same Google search if you don't trust my link.

Process overview: Remove the surround, loosen the top shroud, loosen the outside shroud, flex it back to reach the air intake for the secondary air tube, plug the air intake opening. Do the other side. Done.

Process detail: You will be touching three parts only plus the surround. Refer to the component diagram in the owner manual.

Step 1. Remove the front surround to gain access to insert.

Step 2. Slide your Merrimack forward as needed for clearance.

Step 3. Loosen Top Shroud by taking out the middle screw and the screws on the sides. No need to take out the screws at the back, they are hard to reach anyhow. Flex the shroud up to clear for next step.

Step 4. Let's do left side first. This is where the diagrams differ so I'll document (a) and (b), you pick which applies to your version of the parts diagram.

(4.a) older diagram with named parts: find the Outer Shroud [part #42]. Remove the screws on the side, then flex it out of the way so you can see the bottom of "Left Side Shield 2nd Air" [part #41].

(4.b) newer diagram without named parts: find the Outer Shroud. The part is not numbered but you can't miss the big outermost shroud that covers sides and back to which the top shroud attaches. Remove the screws on the side, then flex it out of the way so you can reach the piece that it covers. This part is also not numbered but easy to see: find part #4 in diagram, to the left of that is an insulator, to the left of that insulator is a piece of sheet metal with the forward part of it shaped to form a channel. That's what you are after. In the old parts diagram it was called "Left Side Shield 2nd Air".

(4.c) either diagram: You have uncovered the bottom of the channel where air is sucked into the secondary air tubes at the top of the firebox. It is about 3/4" x 2" going by memory. Please note that this Side Shield is not as low as the Outer Shroud else you wouldn't even have had to loosen either of the shrouds.

Step 5. Plug the bottom of that channel. I used a thick rope type stove gasket which fit snugly enough not to fall out. Aluminum foil and stove cement will also work. The point of the exercise is to prevent air coming in there, so plug the entrance properly with something that won't shrink or fall out. Only plug the entrance, no need to fill the whole channel.

Step 6. Repeat for the other side.

Step 7. Re-attach the shrouds etc.

You will notice that the air tubes at the top no longer function. You have now restored full control over your fire. It will damp down as you would expect. With just a few pounds of logs before bedtime, you will have glowing hot embers in the morning. Enjoy your Merrimack.

 

[Shrek Ogre]

 

[begreen]

OK, so this is a Federal offense and serious overkill for most people. If you want an old smoke dragon then just install one instead of telling people how to revert their stoves 30 yrs backward. Totally cutting off secondary air in a stove is not a good suggestion.