VC Older Encore 0028 Secondary Air Control??

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Eman85

Minister of Fire
Oct 10, 2022
1,202
E TN
I found a previous thread and bumped it in the general forum. I was cleaning my old Encore and removed the cover on the secondary air flap. I notice the flap is closed cold. I searched and found this older thread with conflicting answers. Should the flap be closed cold and then open as the cat gets ho to allow fresh air in? It appears the spring has a probe that extends it into the chamber to sense the heat.
 
It should be open when cold and shuts as it gets hotter. It has to be timed correctly as well for it to work “correctly “. A lot of us have given up on trying to get the flapper just right and have completely disabled and blocked off the secondary air.
 
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It should be open when cold and shuts as it gets hotter. It has to be timed correctly as well for it to work “correctly “. A lot of us have given up on trying to get the flapper just right and have completely disabled and blocked off the secondary air.
What is the actual intent or purpose of the secondary air? I should have left my cover off and the stove is in use right now so it's a little too hot to work on but I'd like to see if it's doing anything.
 
My quest continues to find out what the purpose of this air shutter is.
 
To keep the draft up in the flue even with the primary set to low. This is to keep a draft stall from happening, a safety feature. That secondary flap allows the flue to draw air not through the combuster but from outside of it and up the flue. This will dilute the airflow within the stove some I believe but theoretically keeps the draft going in the flue so no smoke bails out into the house. I think this is a cause at least in part to the complaints of unresponsiveness of the primary air control. If there is a VC dealer on this forum maybe they could give a yes or no to this but so far crickets. Whether or not other stove brands have this feature , I don’t know but suspect some do.
 
To keep the draft up in the flue even with the primary set to low. This is to keep a draft stall from happening, a safety feature. That secondary flap allows the flue to draw air not through the combuster but from outside of it and up the flue. This will dilute the airflow within the stove some I believe but theoretically keeps the draft going in the flue so no smoke bails out into the house. I think this is a cause at least in part to the complaints of unresponsiveness of the primary air control. If there is a VC dealer on this forum maybe they could give a yes or no to this but so far crickets. Whether or not other stove brands have this feature , I don’t know but suspect some do.
Well... it's open 1/4" cold and closes as soon as the iron of the stove warms up. Stays closed as long as there is fire in the stove. VC emailed me it was too complicated to explain and to call the dealer. I called 3 dealers none knew the exact science of it. The only thing this could possibly do is somehow open if the cat temperature was waay above 1600. I posted pics on another post of what it does when hot. The best I can figure is it might allow cool air to cool the cat before the stove melts.
 
Well the mystery and struggle of the secondary air control continues. When I installed the new probe/coil it was at 4 o'clock and held the shutter open just as it was described it should do. After lighting the stove it immediately closed the shutter even before closing the bypass damper. Now after burning for a few days and letting the stove go cold the shutter doesn't open, the coil is holding it shut. I know it can be replaced but something just ain't right about this.
 
I'm going to pull it off and have a closer look, I can move the shutter door so I know it's not binding. On my other post I had a pic that showed where the tab went around to 7 o'clock. I wonder if it is adjustable. I sent an inquiry to VC, we'll see what they say. I purchased through Amazon so return/exchange is no problem. kind of a joke this costs as much as it does and so far worked once.
There is another Encore owner that is having similar problems with his replacement coil. His rotated so far it reopened the shutter.

OK, got off of my lazy butt and took a closer look. When I removed the screw and moved the coil out just the slightest bit the spring rewound to 4 o'clock. I pulled the probe and looked at the probe and the rod. It appears the way they twist the bimetallic spring to drill the hole for the rod it's bent so it rubs the tip of the connecting rod. The rod has a double bend so it stays engaged in the hole and the tip would rub and bind on the coil. I filed the rod end a little and tapered the side facing the spring so maybe it won't catch.
I reinstalled it and lit the stove and observed the spring slowly close the shutter. As the thermocouple probe got to 500* without the cat engaged the shutter was almost closed. I closed the bypass damper and watched the temp on the probe and at 700* the shutter was completely closed. At 1000* the tab with the rod was at 6 o'clock.
 
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Sounds like its working properly now.
Won't be able to tell until I can let the stove go cold. Should be warm this week and I'll see. I did notice that the replacement rod doesn't have the double 90* bend when I looked one up and saw the pics of it.
Called VC today and actually got a human after hanging on for 15 mins. She was going to transfer me and hung up on me. Tried again and they are going to see if they can find someone to answer my question of how the secondary is supposed to operate and what it's purpose is. We'll see.
 
Will be very interesting to see what they have to say for sure. Some of that info they may see as proprietary for some crazy reason.
 
VC never got back to me, I know hard to believe isn't it!
Stove ice cold this morning and rod got stuck on shutter spring. All I did was touch it and it released to the 4 o'clock position. I'll have to pull it off again andd do a little more modifying.
 
I called HHT (VC) to see why they didn't call me, got a different person today. She searched all she could and had no one else to ask and couldn't find the exact explanation of the secondary air control on the stove. All she could find that had any info was the stove's manual which mentions secondary air and that it is thermostatically controlled but no explanation of how it does this or any temperature specs on proper function.
 
I believe that someone at HHT knows how the secondary air intake works on they're VC stoves. I think the secondary air serves the same purpose on all they're stoves. It's just mechanically set up differently on different models. For some reason they don't want to give you this information or believe you have no need to know it.
 
What is the actual intent or purpose of the secondary air? I should have left my cover off and the stove is in use right now so it's a little too hot to work on but I'd like to see if it's doing anything.
Sorry for the late reply. I don’t make it on the forum much these days. The secondary air feeds the cat. The air is directed up behind the lower fire back up to the hood where the cat access is. The flapper is suppose to regulate the amount of air it receives via a probe in the refractory box. Do you have any sort of cat thermometer?
 
Well the mystery and struggle of the secondary air control continues. When I installed the new probe/coil it was at 4 o'clock and held the shutter open just as it was described it should do. After lighting the stove it immediately closed the shutter even before closing the bypass damper. Now after burning for a few days and letting the stove go cold the shutter doesn't open, the coil is holding it shut. I know it can be replaced but something just ain't right about this.
Disable it and block it off. I have been down this rabbit hole.
 
Sorry for the late reply. I don’t make it on the forum much these days. The secondary air feeds the cat. The air is directed up behind the lower fire back up to the hood where the cat access is. The flapper is suppose to regulate the amount of air it receives via a probe in the refractory box. Do you have any sort of cat thermometer?
Yes I have a K style thermocouple installed with a meter to monitor cat temps.
I have installed a new probe/coil and I have the cover off of the secondary flap. I know where it goes and where the sir flows. I want to know what the purpose of it is and the temps and what position it should be at with those temps.
 
So basic operation of the stove is ( which I’m sure you know, I’m not insinuating you don’t)
Load stove light fire
Flue hits 600* close damper
As cat temps rise, incrementally close primary

Once primary is fully closed this is where the secondary is suppose to take over feeding the cat air as needed. As cat temps rise the coil is suppose to expand thus closing the flapper. As cat temps cool the coil retracts and opens the flapper to induce more air. Problem is it does not work well enough to keep the cat from going nuclear. Sometimes the coil will keep expanding and the flapper will go past completely closed and start opening again on the top resulting in to much air which sends the cat into orbit. To fix this I put a round magnet on the bottom of the stove that would catch the flapper. Other times the flapper does not close fast enough in order to keep the cat below 1600*. It’s just not a trust worthy design. I found myself babysitting the stove to much and always fidgeting with the coil timing and using foil to slow down the air and you name it. I finally gave up, disconnected the rod and positioned the flapper fully closed. The stove is much more controllable. Now all the air comes from the primary which is controlled by me.
 
What you posted about secondary air operation sounds good in theory but far from what this stove does. The secondary air flap closes as soon as the stove itself gets hot, don't even have to engage cat if you burn the first load down to build coals and get the cat and flue hot. Because of this there is no way it would ever cool down enough to let air in for the cat while the stove is burning. I don't have a flue internal temp gauge as I just installed new DW pipe and really don't want to drill into it yet. I do have a magnetic thermometer on the flue adapter just before the DW pipe. If I close primary fully that is when the flashover and smoke puffing happens.
As far as a magnet goes that's a good idea but magnets will fail from heat, have to use high temp neodymium magnets.
 
What you posted about secondary air operation sounds good in theory but far from what this stove does. The secondary air flap closes as soon as the stove itself gets hot, don't even have to engage cat if you burn the first load down to build coals and get the cat and flue hot. Because of this there is no way it would ever cool down enough to let air in for the cat while the stove is burning. I don't have a flue internal temp gauge as I just installed new DW pipe and really don't want to drill into it yet. I do have a magnetic thermometer on the flue adapter just before the DW pipe. If I close primary fully that is when the flashover and smoke puffing happens.
As far as a magnet goes that's a good idea but magnets will fail from heat, have to use high temp neodymium magnets.
So you are running a 1/2 or full load with the damper open to build coals? this seems wasteful to me. Once my flue registers 600* I close my damper. Regardless of how many coals are in the stove. I would also drill a hole in your pipe so you can monitor your flue temps better. The picture I’ve included shows my magnets. They have been there for probably 5 years.
These are obviously my opinions and by no means am I trying to tell you what to do. Simply trying to help. The old crew of VC misfits have been dwindling away over the years, however there are (was) a bunch of us who have discussed proper operation of these older encore and defiants. Much of us share the same methods with the same mods. Doesn’t mean it’s for everyone.

VC Older Encore 0028 Secondary Air Control??
 
@RandyBoBandy So over the years the general consensus is to just keep the secondary air shutter closed? If keeping it closed all of the time works best that's easy enough to accomplish just by putting a washer under the screw and tightening it down. i don't see what
If lighting from cold I'll get a couple of splits burning good before closing the bypass. I've burned this stove without using the cat and I can get plenty of heat and long burns if I close it down, not clean burns but at least 8 hours or more. This year when doing maintenance, changing gaskets and installing new pipe I decided to replace the cat and go back to cat burning. Decided to replace the secondary coil as part of maintenance as someone suggested when I asked about it's function. Now I'm concerned about the secondary causing problems I didn't have before.
 
@RandyBoBandy So over the years the general consensus is to just keep the secondary air shutter closed? If keeping it closed all of the time works best that's easy enough to accomplish just by putting a washer under the screw and tightening it down. i don't see what
If lighting from cold I'll get a couple of splits burning good before closing the bypass. I've burned this stove without using the cat and I can get plenty of heat and long burns if I close it down, not clean burns but at least 8 hours or more. This year when doing maintenance, changing gaskets and installing new pipe I decided to replace the cat and go back to cat burning. Decided to replace the secondary coil as part of maintenance as someone suggested when I asked about it's function. Now I'm concerned about the secondary causing problems I didn't have before.
I feel your pain. I’ve been through all the same stress you are going through. I’ve sat behind the stove with a flashlight watching the flapper. I’ve tried retiming the probe. I’ve replaced the probe. I’ve wrapped the cover in foil. You name it, I’ve tried it. In the end I just took out the washer and tighten down the screw so the flapper won’t move, disconnected the rod, and for safe measure put the two magnets just under the flapper. When I installed a new refractory box and upper fireback last year I didn’t even bother putting the secondary probe back in. I’m still running my cat though. It works just fine. There’s just a slight variation in technique of running the stove. At this point it’s worth a shot right? What else do you have to loose other than countless hours fidgeting with the damn thing🤣
 
I might do as you say and just disable and keep the shutter closed. I am getting tired of the anxiety of watching it and concern that the coil will open the shutter when the cat is at 1600 and it overfire. I still have my old probe that I can install to plug the hole.
Tell me what different technique you've used in running the stove? Does the secondary being open when cold really make any difference in any operation of the stove?
It sounds like there were a lot of people that had problems with the secondary on these stoves. I searched and didn't really find much about the secondary on an Encore.
 
Primary air operation might be slightly different and that’s about it really.