Airtight door conversion

[miohman]

Has any one successfully converted their doors to an air tight set up? I'm looking to set up a blower AUF and AOF but still haven't really figured out how to convert my doors.

Micah

[CharlieVT]

I've done a couple.
converted an oil fired arch to wood fired with home brew air tight door. I have posted pics on this site but I'd have to search a little to find them.

I also converted a friends wood fired by removing the two cast iron doors and using the hinges that were case into the arch front to support an airtight door and latch. No modification to the arch front was made, so the arch could be reverted to original if desired. I don't have pics of this conversion, but could take some sometime.

The basic door design was the same for both conversions, but the hinge and latch setups are quite different. I'll look around for some pics that might help give you some ideas.

addendum: here's a thread with pics of my oil fired arch conversion: http://mapletrader.com/community/sho...497#post260497

The cast iron arch front I converted is across state lines, it'll take me a few days before I have a chance to take pictures of that. The door for that conversion was fabricated the same way, but the channel for the braided rope door gasket was shallow so the rope gasket would press against the surface of the arch front around the perimeter of the firebox opening. One larger airtight door replaced the two original cast iron doors. The door's hinges were fabricated to use the original hinge tabs cast into the arch front on one side of the fire box opening. The hinge tabs on the other side of the opening were used to mount a latch mechanism. You get to decide if you want a right swinging or left swinging door before you begin fabrication.

If your arch front is carbon steel, drilling and welding to it would be less daunting than for a cast iron door. I didn't want to get into trying to weld or drill the cast iron arch front; that's why I fabricated a door that didn't require any modification to the arch itself.

HTH

[Chicopee Sap Shack]

Charlie how did you make the window glass in the door?


Sent from my iPhone using Tapatalk

[CharlieVT]

...how did you make the window glass in the door?...

That was really easy. But kinda 'spensive. The glass isn't cheap.

Just google for "heat resistant sight glass" and shop around for a size and price.
I cut a hole in the door a little smaller than the glass I purchased.
I welded up a little frame using angle steel, bedded the glass with some arch insulation, and mounted it to the door with sheet metal screws.
Cut a tunnel in the door insulation... and that's it.

There is a document for converting an arch to high efficency that I used for guidance when I did my AOF conversion. The article suggested blower and air jet sizes, in addition to things like a draft gauge, sight glass, automatic draft damper.
Here it is: http://www.uvm.edu/~pmrc/Combustion.pdf
I did the draft gauge and sight glass, never got to the draft damper. I wouldn't bother with the sight glass or draft gauge if I were to do it again.
You can "tweak" a home brew AUF/AOF by watching the stack temperature (a good digital stack thermometer with a thermocouple inside the stack IS a good idea), watching the smoke (or lack of smoke) coming out of the stack, and the boil in the pans.

I don't doubt that you can further increase efficency with a sight glass, draft gauge, atmospheric damper, etc. but frankly I don't think "the juice is worth the squeeze".

[madmapler]

I just started another thread on the conversion I've been working on so you can see it. My door looks similar to Charlies with a few differences. I really like his hinge design and would definitely gone that way had I thought of it.

[Flat Lander Sugaring]

1st get rid of the plural Doors and go to door, will be much easier. I used hinges and latching system of a small trailer. I can open door and lift off if I had to for some reason. I put a window in my door works ok, glass is expensive but I work for a company that has a glass shop. I used rope for a wood stove glass to seal mine, just happen to have some ;laying around.

[CharlieVT]

In an earlier post I said I'd take pics of a door I fabricated when I got a chance.
The evaporator belongs to a friend. It is a Grimm about 2.5' x 8'.
There is a squirrel cage blower for forced draft (air under fire).

I didn't want to try to drill or weld the front, and I wanted to be able to revert to the original cast iron doors in case of a problem.

Sorry for the pics, the sugarhouse was dark, and the arch front rusty, so contrast of the pics isn't great. The door has seen about 3 or 4 years of use since fabrication. The only repair was to replace some of the insulaton; we had to "train" some of the volunteers who help with firing to not "push" the firewood in with the door like they used to with the cast iron doors.

(Actually, for proper firing, the wood should be forward in the fire box and not up close to the door anyway.)

The left side door hinges are tabs welded to the door frame with holes drilled to the same diameter as the hinges cast into the arch front. A steel rod serves as a single hinge pin for both hinges:


The latch base is a piece of flat bar with tabs welded on the back of it. The tabs are drilled to the same diameter as the holes in the cast hinges on the arch front. These tabs need to be flush with the arch front or the whole latch assembly will rotate during closure preventing tight closure. The latch base is then attached with a steel rod similiar to the way the door hinges are:


A piece of angle iron is welded to the door front where the latch contacts. There is a "stand off" piece welded under this angle iron so when the door handle is pushed down it pulls the door tighter against the arch front:


The door frame is made of angle iron. A second frame of smaller angle iron is inset to create the channel for the braided rope door gasket (purchased from a woodstove supplier). The main panel of the door is just a piece of sheet metal tack welded into the frame. Long stainless bolts are tack welded to the door and project into the firebox to support the blanket insulation. Stainless washers and nuts retain the insulation on the bolts. The blanket insulation is trimmed so that it projects a couple inches into the firebox beyond the opening in the arch front. Sorry, really bad picture: see attached thumbnail number 2 below for a pic of the door interior.

I hope my description isn't too confusing. I'm happy to try an answer questions. And I hope my method gives others some idea on how to proceed with their own fabrication.

[CharlieVT]

I had an inquiry regarding details of my arch front conversion from dual cast iron doors to an air tight.
Sorry, my pictures are so bad, maybe these sketches will help give an idea what I did to add an air tight door to a cast iron arch front without drilling or welding:

IMG_1365.jpgIMG_1366.jpg

[PerryFamily]

Here's some pictures of mineimage.jpg
Works awesome
Only modifications to the arch front was trimming the inside of the original hinges to accommodate the door image.jpgimage.jpg

[CharlieVT]

Here's some pictures of mineAttachment 14006
Works awesome
Only modifications to the arch front was trimming the inside of the original hinges to accommodate the door Attachment 14005Attachment 14005

I like that. Thanks for posting. I like your design of the latch receiver, nice and simple.