Harmen Mark III Glass Replacement

ReluctantRhino · Post by **ReluctantRhino** » Sat. Dec. 24, 2016 12:58 pm

Appreciate everyone's time and help, I'm a new guy to the site.

I bought a house with a Harmen Mark III stove. The gasket around the glass in the door needed replaced. I did some research, watched some instructional videos, then attempted the fix. When I burned the first fire at low heat to let the adhesive set, I notice ash was gathering on the window. I let the fire burn out after two hours, and the next morning I noticed the glass was cracked? It wasn't cracked before the fire? What went wrong lol?

Thanks for any information I can use to gain some needed knowledge.

Cap · Post by **Cap** » Sat. Dec. 24, 2016 1:50 pm

Is this the first time you used the Harman? After the gasket replacement? Was the glass very clear & new looking?

rberq · Post by **rberq** » Sat. Dec. 24, 2016 2:23 pm

Did you replace the round fiberglass door gasket, or the very-thin gasket between the glass and the cast iron door??? If door gasket, that should have no effect on the glass. If glass gasket/clips/screws, then too much tightening or uneven tightening or uneven gasket thickness could stress the glass. Did the crack start near a screw?

I removed my stove door two summers ago, polished the glass with fine sandpaper, and put the door back on the stove with everything looking perfectly fine. A couple weeks later I noticed a big crack in the glass, didn't even need to burn my first fire for it to crack.

I had barely even touched the clips during my polishing. The crack started where one of the clips just barely overlapped the glass, so I think all the pressure of that one clip was concentrated on one very-tiny area of glass, even though the screw was not tight at all.

ReluctantRhino · Post by **ReluctantRhino** » Sat. Dec. 24, 2016 4:06 pm

Thanks for the replies:

-I have been using the stove for a year now, I absolutely love this thing. This would be a case of operator error, or my lack of knowledge that caused this.

-Yes the crack is near a screw and I wondered if over tightening was the case

I used a round gasket rope? Did I use the completely wrong gasket? The more research I do, I am seeing specific glass door gaskets? I concede on this one, I'm a knuckle head! lol

Thanks again, you guys are extremely helpful!

ReluctantRhino · Post by **ReluctantRhino** » Sat. Dec. 24, 2016 4:10 pm

Cap

I have been using this stove ad it is well over a year old. I cleaned the cleaned the glass with the proper cleaner, everything that gathered on the glass was from one single fire.

I appreciate your time!

freetown fred · Post by **freetown fred** » Sat. Dec. 24, 2016 4:11 pm

R, as long as we live & learn, that's the impt. thing. From one knucklehead to another!

titleist1 · Post by **titleist1** » Sat. Dec. 24, 2016 5:10 pm

The gasket that goes around the door glass is flat. I can't remember if it is 3/4" or 1" wide, but it folds over the edge of the glass. It doesn't go all the way around the perimeter, just on the sides and slightly around each corner at top and bottom. Most of the bottom and top are left open for air wash on the glass and secondary air.

I cracked one the first year I replaced mine too. I burned it for a while like that before replacing it.

Cap · Post by **Cap** » Sat. Dec. 24, 2016 7:46 pm

Yep, that's it. You have to use the flat style gasket and the glass remains somewhat loose. Sounds as if it was unable to move and cracked.

rberq · Post by **rberq** » Sun. Dec. 25, 2016 8:16 am

Cap wrote:... the glass remains somewhat loose ...

Yes. My stove doesn't have glass gasket, just glass in contact with iron. The screws are tightened only to the point that there is no play, but the metal clips can still be moved by hand.

deepwoods · Post by **deepwoods** » Sun. Dec. 25, 2016 2:32 pm

rberq wrote:
Cap wrote:... the glass remains somewhat loose ...
Yes. My stove doesn't have glass gasket, just glass in contact with iron. The screws are tightened only to the point that there is no play, but the metal clips can still be moved by hand.

Ditto: My DS machine door glass was cracked when it came time this fall to think about firing up. How or when it cracked I do not know as it was solid when I shut down last year. I thought I had it safely stored away from activity in my basement but it cracked anyhow. New glass ordered from DS Machine said do not overtighten retainer screws. Had wrap around gasket included. So far working fine

rberq · Post by **rberq** » Sun. Dec. 25, 2016 8:09 pm

deepwoods wrote:New glass ordered from DS Machine said do not overtighten retainer screws. Had wrap around gasket included.

I think the trouble with my original DS Machine glass was, it was cut very skimpily at the top of the arch, so it overlapped the metal only the tiniest bit, maybe 1/64 inch. So all the pressure was on that minute area. Interesting their glass now comes with gasketing. That should make it a little more forgiving on pressure points. I took my door and cracked glass to a local glass shop, pointed out they should cut the arch better, and the overall cost was around $90 as I recall.

deepwoods · Post by **deepwoods** » Sun. Dec. 25, 2016 9:21 pm

Here's another example. My upstairs Hitzer 50-93 had crazed glass after 4 months of running. It had not been over heated, ever during that time period. I called Hitzer and politely complained about the door glass, with my purchase paperwork on the stove which I offered to send them if needed. Knowing the glass is not covered by their warranty I thought I would be told just where to go, but to my amazement the lady on the phone said she would give me a break on the cost and I got it for $39.00 shipped

That was with a gasket included! Great people to deal with. New glass is great with no flaws since running start in October.
I wonder if the quality of this special glass can vary from maker to maker or even lot to lot?