Hearthstone Manchester running Too Hot from secondary's?

[travelerstro]

Long time Lurker, first time poster. I have a hearthstone Manchester that was installed in February (2022). It is the 8362 model.

The stove runs 6" double walled excel pipe up 12' to my ceiling, joining into class A chimney pipe though a very tall attic and out the roof (straight up). I think the total length is probably around 30'.

The House itself is a 110 year old half insulated farm house so it draws very very well. I am burning 3 year old split post oak that is around 15 percent.

Really happy with the stove and the heat output but concerned over the stove top temps that happen during the secondary burn. This thing really throws the flames out the top, even when my primary air is shut down all the way (I run 95% of the time this way because of this concern). It was only around 44 degrees this morning and with a full load my IR gun is reading a few degrees below 700 and it is not uncommon for the stove to see this temp every other load even when the air is shut all the way. The secondary's are really Jetting out like a torch and I can hear it roaring when standing in front of the stove.
It only happens for the first 1.5" hours or so until the wood is done off gassing. It will then settle in at around 400 for a few hours before tailing off.

Since this stove has a jacket around the top its hard to get a good reading. Ive been shooting through the top holes and it seems hottest right above the 2 cats i think. I know cast Iron isnt rated to the same temp limits as steel and the manual is no help.

I engage the cat lever as soon as it reaches the active zone and have also tried shutting down the primary air prematurely to try and get ahead of this potential overheating problem. I almost always reach the "too hot zone" of the cat temp probe" which is also concerning.

Maybe I have too much draft and a damper should be installed but my dealer is leaning really hard against this stating that these new EPA stoves shut down pretty tight and they very rarely ever have to install one on a stove like this.

Am I worrying too much or over analyzing this thing?

Any suggestions or comments would be very much appreciated. I have run through around half a cord of wood so far. See below pics for reference

 

[begreen]

With a 30' straight-up stack it sounds like a key damper in the stove pipe may be needed to tame the strong draft. The new Hearthstones like a healthy draft but they do not shut down all the way. AFAIK the secondary air is still unregulated. In mild 40º weather you may be able to leave the key damper open, but in cold weather the draft will increase in strength. That said, the stove temps are hot, but not overly so. If it stays below 700º I wouldn't worry too much.

How many fires have you burned so far? A new cat will be a bit hyperactive for the first week or two but it should settle down.

 

[travelerstro]

With a 30' straight-up stack it sounds like a key damper in the stove pipe may be needed to tame the strong draft. The new Hearthstones like a healthy draft but they do not shut down all the way. AFAIK the secondary air is still unregulated. In mild 40º weather you may be able to leave the key damper open, but in cold weather the draft will increase in strength. That said, the stove temps are hot, but not overly so. If it stays below 700º I wouldn't worry too much.

How many fires have you burned so far? A new cat will be a bit hyperactive for the first week or two but it should settle down.

Thanks Begreen.
I probably have around 50 or so loads run through it so far. I also think that the temps right above the cat's on this stove will be the hottest wasn't sure if this was in line with what other folks are seeing. Is it normal to see secondary's blowing this hard?

If I do end up installing a damper I might have an issue configuring it into place. I think my installation guy went strait up without any telescoping pieces of pipe to the ceiling box.

 

[neverstop]

I believe the manual says 30ft is the max chimney height. Probably worth having the extra control should you need it since secondaries are unregulated.

My only other comment would be to pull all the coals forward so the entire load doesn't off gas at once. And try to ensure the front most split doesn't have an air gap underneath it to the rest of the load. I've noticed flames reaching underneath the first log and igniting the logs behind it then more of the load off gasses at once.

 

[travelerstro]

I believe the manual says 30ft is the max chimney height. Probably worth having the extra control should you need it since secondaries are unregulated.

My only other comment would be to pull all the coals forward so the entire load doesn't off gas at once. And try to ensure the front most split doesn't have an air gap underneath it to the rest of the load. I've noticed flames reaching underneath the first log and igniting the logs behind it then more of the load off gasses at once.

Much appreciated, I’ve always read on here to rake coals forward before reloading and never put 2 and 2 together. Maybe my first big split should be up front and flat.
I also noticed you run the shelburn. Do you stack on top of the dog house when loading? (Main air feed in the stove)

Thank you for your help

 

[neverstop]

Much appreciated, I’ve always read on here to rake coals forward before reloading and never put 2 and 2 together. Maybe my first big split should be up front and flat.
I also noticed you run the shelburn. Do you stack on top of the dog house when loading? (Main air feed in the stove)

Thank you for your help

I have before but haven't stacked it well enough and a split always rolls into the door as the load burns down

 

[mdocod]

We had essentially the same problem on our Mansfield and the temporary stove we were running before it arrived. The steel stove before it was shooting to 700F+ territory, the sides of the Mansfield were hitting 650F... too hot. Had to run light loads of wood and go full choke for the first hour or 2 to keep it from snowballing over 1000F EGT's.

I have 13' of stove pipe to the support box / chimney adapter, and about 8-10' more chimney above that, so maybe about 21-23' total, straight shot.

The dealer/installer here recommended single wall stove pipe for this application to extract some heat and tame the draft a bit, but I went with double wall because I was concerned with too much heat-loss in the pipe. The dealer was right. The double wall over-fired stoves even on full choke, and we're at 7400' elevation here so ~22' of chimney shouldn't be all that overkill on the draft effort.

Switched to single wall, now the stove regulates EGT's and surface temps perfectly with full loads of wood in the recommended air-control setting range. A bit of cooling/condensing in the pipe settles the system down to perfection, and we're getting noticeably more heat in the home this way and full proper burn cycles from full loads of wood.

Many folks here on the forum will tell you not to use single wall for a long run as a way to solve this problem and there is validity to that perspective, as adding additional heat-sinking to the exhaust increases the risk of developing creosote that could lead to a chimney fire. I am carefully monitoring this and have not seen any reason to be concerned. Just the usual light soot deposits on the chimney system, same as we were getting on the double wall, in fact, less now because we can drive 800F EGT's during the dirtiest part of the burn with no risk of runaway. Before I was usually trying not to let it go over 600F to prevent snowballing out of control. 800F into single wall at this volume is probably maintaining higher EGT's through the chimney system than 600F was before on double wall. I have another temp probe on the way to install up near the support box to monitor this.

I suspect that with 30', you may need a damper either way, but if you have the clearance for single wall it's something to carefully consider.

 

[travelerstro]

Very interesting… thanks so much for posting. I would love more heat and to get stove temps down would be a double whammy by switching to single wall.
I think according to my manual I just need to slid the stove forward 3 inches and redo my ceiling box but I’m worried about not having enough room in front of my pad for clearance. I currently am running 16” so that will move me to 13”. I do have the close clearance heat shield.
However I hardly ever load from the front unless I’m starting from a cold stove. (Side door is easier to operate when reloading)
Is the 16” requirement a heat safety type of thing like the combustible or is this more for coals rolling out during a reload?

Again thanks for sharing!

See attached pics

 

[mdocod]

For that installation I think you're best served to leave the double wall in place so that you can keep your tight spacing to the wall and maintain that hearth space in front of the stove. I would only entertain trying the single wall out if you already had the clearances for it, as it's a cheap drop-in test at that point. Having to move the support box and address the alignment of the chimney system above that would be a big messy destructive job that probably isn't worth it.

I would start with a key damper and see how that goes.

 

[travelerstro]

For that installation I think you're best served to leave the double wall in place so that you can keep your tight spacing to the wall and maintain that hearth space in front of the stove. I would only entertain trying the single wall out if you already had the clearances for it, as it's a cheap drop-in test at that point. Having to move the support box and address the alignment of the chimney system above that would be a big messy destructive job that probably isn't worth it.

I would start with a key damper and see how that goes.

Thank you. I know it would be a pain to move the cieling box and I already have a pipe damper. Just have to install it and see if it will help regulate temps better.


I wish I would’ve done single in the house to start out with but hated to lose that living room space.

 

[travelerstro]

Can someone explain to me how to properly use a pipe damper on my setup?

As mentioned the reason I want to add one is the stove runs too hot due to my almost 30 foot run of pipe. (High draft)
It seems though that a damper would actually make my stove run hotter rather than cooler because it would be trapping in more of the hot exhaust gasses being thrown from the cat?

 

[moresnow]

For that installation I think you're best served to leave the double wall in place so that you can keep your tight spacing to the wall and maintain that hearth space in front of the stove. I would only entertain trying the single wall out if you already had the clearances for it, as it's a cheap drop-in test at that point. Having to move the support box and address the alignment of the chimney system above that would be a big messy destructive job that probably isn't worth it.

I would start with a key damper and see how that goes.

This^

If the standard damper install is still insufficient some of the damper opening can be blocked for another try. From what I've been told

 

[BotWoogy]

Check the opening on your air intake and make sure it’s proper. If it’s easy to access you could put some tape over the hole and see what happens. See If it doesn’t choke the fire down. This is temporary

 

[travelerstro]

Check the opening on your air intake and make sure it’s proper. If it’s easy to access you could put some tape over the hole and see what happens. See If it doesn’t choke the fire down. This is temporary

Appreciate the suggestion. I will take a look and see.
I’ve also installed a stove pipe damper. Hoping this will help throttle back the temps once that secondary gets crazy.

I did also stack a bigger log right in front of the dog house main air feed and it’s helped quite a bit too I think.

I’ll report back once it gets cold enough to burn again. Our lows have been only in the mid 40’s to 50’s and highs are back up in the 70’s

 

[travelerstro]

good morning

Revisiting this one again. I installed a key damper on this setup last year but I still feel as though I’m running too hot.
Got around a cord of wood through this stove so far this year but can’t seem to keep the stove pipe temp below 750 for the first 2 hrs even with everything shut down. Stove runs around 700 during this time period as well until the secondaries are done.

Then it cruises fine for the next several hours and still has plenty of heat/ coals the next morning for restart.

Any ideas on how to keep this thing from getting so hot?

I’ve tried every variation of shutting down in phases and stacking wood to keep from tunneling under the load. (More of a side loader stove anyways)

Thank you

 

[travelerstro]

Sorry. Last pic of ir thermometer reads right at 700.

 

[begreen]

Most of the air control once the fire is going will be in the last 20% of the control range. Try to shut down the air sooner and more assertively as long as the cat doesn't go inactive. Then close the key damper.

Also, when the stove is cold. Check the stove door gasket to make sure it is well-adhered in place. It should stick in it's channel when give a gentle tug. Make sure the ashpan door is sealing tightly.