Harman over fire ports and burn pot gasket design?

[Don2222]

In the Harman Advance, Both over fire Ports at the base of the flame guide were blocked with pellets and there was a lot of hard black carbon in the Burn Pot. So I got a new Harman burn pot gasket.
Are the tops of the over fire ports supposed to line up with the OEM Harman burn pot gasket knockout holes??
Why does'nt the gasket have the channels in it?
Main question.
Why are the gasket knock out holes so awkward in location and size?
How much air flows behind the burn pot?
Am I missing something?
See pics

 

[alternativeheat]

So the air moves behind the gasket in that channel cut into the flange. I've seen this done in automotive gaskets as well under things like carburetors and throttle bodies.. I guess your concern is with the fact that the gasket isn't cut like the flange is ?

 

[Don2222]

So the air moves behind the gasket in that channel cut into the flange. I've seen this done in automotive gaskets as well under things like carburetors and throttle bodies.. I guess your concern is with the fact that the gasket isn't cut like the flange is ?

Yes you are correct.
I tried cutting a gasket with 2 even slots at the top, however the pellets liked to get stuck in there and clogged the ports and stopped the air flow. So maybe that is the reason the gasket is not cut with the 2 holes close to the top. However I have no clue why the 2 holes are cut where they are (see pic above) and different shapes too???
The bottom part of each hole does go over part of the channel behind the burn pot.
Knowing Harman there maybe a good reason but they are not Sharing it???

 

[alternativeheat]

The whole engineering of the passages looks to be providing secondary air to the flame. I'm no engineer by any stretch of the imagination but that would appear to be the purpose to me. it's common on some older coal stoves I know. I doubt the gasket you showed would block that from happening, the passages being pretty deep looking. I wonder if this design was an attempt at controlling emissions output.

As to how pellets got behind there, no clue on that !

 

[Don2222]

The pellets did not get behind there, they just blocked the exit at the top of the burn pot.
The purpose of this secondary air is to push the flame forward to keep it from lapping the brick backing and making it black.
After further investigation, I found this feeder welderment repair kit that contains 3 configurations of the burn pot gasket.
Configuration #
1. -no extra holes for some older stoves and current stoves that do not need over fire air like the P61
2.-two extra holes for the Harman Advance that need a lot of over fire air.
3.-one extra hole for stoves models requiring some over fire air such as the smaller P43
I starting to believe these holes add air pockets to improve the flow of over fire air?
See
http://www.stove-parts-unlimited.com/Harman-Feeder-Repair-Kit-p/1-00-677150.htm

What would you say?

 

[alternativeheat]

Ya know what ? You're conversing with someone who would probably spread out a bead of high heat RTV and slam the sucker together. 46 years as heavy truck and equipment tech and RTV came to be our best friend. If it was good enough for manufacturers to do factory assemblies of things like differentials and tranny covers and side covers and it lasted the life of the truck, it was good enough for us.

Engineering of the housings I can't say much about, I have to assume it's all a work in progress by Harman engineers though. As to those gaskets, if they have holes in the right places they will work. And even if there are extra holes but are sealed or entrapped by the flanges, why would that matter as long as there is no air leak ?

 

[Don2222]

As to those gaskets, if they have holes in the right places they will work. And even if there are extra holes but are sealed or entrapped by the flanges, why would that matter as long as there is no air leak ?

Those extra holes must be there for a reason, maybe to improve Over Fire air flow?
It seems to be a secret but we should know which gasket to get when working on these stoves. Knowing the reason would help. That is all.

 

[alternativeheat]

Yeah I here ya.

 

[Lake Girl]

Those extra holes must be there for a reason, maybe to improve Over Fire air flow?
It seems to be a secret but we should know which gasket to get when working on these stoves. Knowing the reason would help. That is all.

Have you tried contacting Harman for an explanation?

 

[smwilliamson]

In the Harman Advance, Both over fire Ports at the base of the flame guide were blocked with pellets and there was a lot of hard black carbon in the Burn Pot. So I got a new Harman burn pot gasket.
Are the tops of the over fire ports supposed to line up with the OEM Harman burn pot gasket knockout holes??
Why does'nt the gasket have the channels in it?
Main question.
Why are the gasket knock out holes so awkward in location and size?
How much air flows behind the burn pot?
Am I missing something?
See pics

I think he knock out holes are for: 1. the one on the right is anything with pressurized ignition and 2. the one on the left PC-45 agitator mechanism. I think the gasket needs a nip taken out at the top of each passage.

 

[smwilliamson]

actually now that I think about it, none of the gaskets have that cutaway because the air is channeled over the gasket, look at the burn pot, there is a double layer of steel and it's notched out so the air is diverted over the gasket.

 

[Don2222]

I think he knock out holes are for: 1. the one on the right is anything with pressurized ignition and 2. the one on the left PC-45 agitator mechanism. I think the gasket needs a nip taken out at the top of each passage.

The agitator connects right into the auger so that hole could not be for that.
Both hole are high, I thought the ignition hole is lower down?

 

[Don2222]

Here is a Harman Part # 3-44-724114 for one gasket configuration and the models it fits.
Not sure if this helps or makes it more confusing?
Do all these models have the over fire ports?

Why does the 52i need 2 gaskets? In case it plays golf and gets a hole in one? LOL

 

[Don2222]

Have you tried contacting Harman for an explanation?

Thanks Lake Girl
I just opened a Harman support ticket with Tammy @ HHT headquarters in MN and sent pics and detailed info. Now just waiting to hear back.

 

[alternativeheat]

Let us know what you hear Don.

 

[smwilliamson]

The agitator connects right into the auger so that hole could not be for that.
Both hole are high, I thought the ignition hole is lower down?

In the pressurized ignition pots, PB105, Hydroflex60 and the PF100 where the pressurized ignition is used the igniting element comes in high on the right side at an angle. I know that what the right knock out is for. Not sure about the left. But if you knock them out on a regular pot it will screw up the air flow I'm sure

 

[Don2222]

In the pressurized ignition pots, PB105, Hydroflex60 and the PF100 where the pressurized ignition is used the igniting element comes in high on the right side at an angle. I know that what the right knock out is for. Not sure about the left. But if you knock them out on a regular pot it will screw up the air flow I'm sure

Ok
Then it is possible to flip the gasket over so the left hole is on the right. Then maybe there are 2 different types of holes of the pressurized ignition on different models? Are they all in the same place?
Removing the knock outs on a regular burn pot shouldn't make a difference since the pot is still sealed from the auger chute and the fire box.

 

[Don2222]

While I am waiting for HHTs answer I did more research and this is what I found

Pic 1 shows a PC45 Gasket for early models Pre-Serial # 008055950 - This makes sense looking at Pic 2 (This gasket is Harman part # 3-44-724115)
Pic 2 shows Page 22 of the Harman PC45 Manual with the new gasket in pic 3 with the 2 holes punched out!
The gasket in Pic 1 looks like a better fit.
The reason they may show the new gasket in the PC45 manual:
I have see Harman try to standardize on common universal parts like the auto lite 3 knob circuit board with new dip switch settings that even works in the Invinsible RS but it does not say.
Pic 3 shows a new burn pot upgrade for PB105 and PF100 -- Harman part # 1-00-73560
Pic 4 shows new burn pot gasket (Comes in a set with tail pipe gasket or exhaust flange gasket -- Harman part # 1-00-07381)

Therefore:
It looks like the PC45 manual suggests the new gasket in Pic 3 will fit all Harman models and the 2 knock out holes are for the upgraded burn pot on the PF100 and PB105 and the PC45?

It is confusing
Do you guys agree? Any Comments?

 

[Don2222]

Hello

Got the official word back from Harman.
This is a universal burn pot gasket and the punch out holes are for some models.
However
Their exact instructions are to ALWAYS remove the punch outs when installing this gasket no matter what model it is being installed into.
The reason being is that it is possible during installation for the punch outs to become loose and be disloged and get into a position where they should not be!

 

[smwilliamson]

Interesting....

 

[Lake Girl]

Good to know Don. Thanks for checking with Harman for their take on it.