View Full Version : Anyone build their own fireplace doors?
01-31-2008, 11:42 PM
I have to get some airtight fireplace doors for a masonry fireplace in the new house. This is a Rumsford fireplace, so of course the opening size is nonstandard and will require custom work. I've started pricing these things and I'm astounded, I mean _really_ astounded at the cost.
OK, I have a shop, I can weld, these don't require tenths accuracy, steel is cheap and sending frames out for plating isn't a big deal, so this should be a reasonable project.
Anyone have any experience to share? Parts sources, things to look out for?
I did run across a really cool ceramic for the doors called neoceram. It has pretty much zero coef of expansion - the blurbs show it being heated yellow hot from below while pouring water on it from above. Way cool.
Of course, if the window has 0 coe, the steel frame is still going to expand when it gets hot so there has to be some float.
For energy efficiency, these have to be pretty airtight. I have an external air supply in the base of the hearth and the house is superinsulated.
I'm going to have to start schlepping through fireplace accessory stores to look at construction methods.
what do you think?
02-01-2008, 12:16 AM
I have been thinking about puting a glass insert in my fireplace door.
When I heard what they want for the glass I had sticker shock.
But I've been thinking about trying the clear glass Pyrex cooking pans
that you can buy from Walmart for about $ 8 bucks. Hard part is mating
glass to metal so it does not crack.
02-01-2008, 12:28 AM
I put in a year working in a blacksmith/welding shop in the late seventys.
In that time I built two door/frame assy. They both were bifold as I recall. 'Quarter in. HR as flat as possible. Put together with rivets to ward off warp. Both would hold a fire over night. Customers were happy.
02-01-2008, 12:44 AM
Unlike modern fireplaces a Rumsford fireplace was designed to heat the house and to a lesser extent to cook with. The are designed so you can build the fire out on the hearth as aposed to in the fireplace. If you have a true Rumsford the fire box will only be 12" or so deep in the center with 45 degree wings on both sides. A Rumsford will also have smoke shelf where the damper is located that will cover the throat. The throat will be the length of the fireplace and only 3"-4" wide. They really do not lend themselfs to fire place doors.
The last one I designed cost $110,000 to build. It looked nice but the mason screwed it up by not following my plans. The mason made the throat 12" wide and left out the smoke shelf. He had never built a Rumsford before and thought he knew what he was doing but the fireplace smokes so bad the owner does not use it. It is a shame because all the sizes were worked out long ago so with the proper refference and following all the long existing tables there is no chance for failure. Gary P. Hansen
02-01-2008, 12:58 AM
I've no expertise on door design, but I notice that the sealed wood stove I have uses what's probably a fiberglass braided rope to seal the door and to bed the window. There are little screwed hold downs around the edge of the glass to keep it in place. I think you could imagine the rope as a face seal O-ring with room around the glass frame to accomodate steel expansion. The "straps" of the strap clamp hold downs are just sheet metal, so they might maintain some spring force. Or maybe not.
02-01-2008, 01:43 AM
The air barrier can rest in a socket that has silicone seal under in a shear situation. Excellent elongation. The socket would be cooled by exposed area between sockets.
As long as seal does not exceed its temp limit sheilded from fire you are good to go.
I say air barrier because you need to identify a lens for the infra-red to pass through. At this writing I don't have confidence in boro-silicate being all that transparent to IR.
Those @#$$#@ "beauty" doors get my dander up.
Poor heat transmission, just looks, and a ROYAL pain to maintain the fire AND the fire place.
AFAIK, A soap stone Franklin Stove beats Rumsford all hollow. Adapt an inline heat exchanger to the stack and you can recover a bunch of that heat too.
I'm off my box now. Ag
PS These days you can buy a chimney top damper, controled by a stainless cable down to a doodad just beside the fireplace opening. Works like a butterfly valve, and dang near seals air tite when closed. Ag
I've started pricing these things and I'm astounded, I mean _really_ astounded at the cost.
The cost is not just the usual ones - they also have to be certified by the NFI.. Which brings up another point - if you have homemade doors, and windup burning down your house, expect your insurance not to cover it. You also may want to know that most of the heat comes from direct radiation, so doors may not be the best idea.
But I've been thinking about trying the clear glass Pyrex cooking pans that you can buy from Walmart for about $ 8 bucks.
Uhm, just so you know, Pyrex is no longer made with Borosiciliate glass. It's now made with plain old Sodalime, and many people have noted that it tends to shatter unexpectedly when it's hot.
Unlike modern fireplaces a Rumsford fireplace
??? I was under the impression that pretty much ALL fireplaces(with the obvious exception of ones built for effect) built since 1790 or so followed Count Rumfords design spec. Heck, they'res something like 2 and a half pages of my Architectural Construction book from College devoted to the Rumford design..
Besides, Fireplaces, even "efficient" ones, are pretty horrible ways to heat a house with wood - a cast iron stove, let alone a Masonry(IE "Finnish" or "Russian") stove beats them in terms of efficiency. But then, neither look as nice.:)
02-01-2008, 09:34 AM
"Modern" fireplaces are designed to send most of the heat up the flue. The Rumsford can only be used if it is cold outside because they put so much of their heat into the house. Gary P. Hansen
02-01-2008, 11:47 AM
Thanks for the ideas
The absolute worst subs I've had to deal with were masons. They would not follow plans, look at what they had written down or, at times, even at what they were doing. I've had 4 or 5 on different projects and they all screwed something up. I haven't had a fire in the fireplace yet, so I still have my fingers crossed that it draws correctly. It's a little deeper than the classic Rumsford, maybe 18-20 inches. Call it a modified Rumsford. What I want to call the masons is unprintable.
This is more architectural than for heating - it's the second backup (primary geothermal/solar, backup radiant/propane, desperation - fireplace) The house is a passive solar design and I use the fireplace as part of the thermal mass. Nobody in their right mind builds a masonry fireplace these days, it's too complicated, too expensive and it's very hard to find a mason with a clue as to what they're doing.
I could keep going on, this has been a major PITA project. <end rant>
Neoceram is a ceramic, not glass, that transmits 90% of IR in the 3.5 - 10.5 micron range. Nippon Electric makes that, Corning makes a somewhat similar product called Pyroceram. I don't mind paying $$ for materials, just for labor when it's within the range of my capabilities
I was going to go with HR, maybe 3/8. Each door is somewhere around 18w x 36h. No real design yet, I'm just thinking out loud. I'm going to have to get a tape meaure out next time I'm at the site.
Agrip, I don't quite get a picture of what you're describing. Is the socket in the frame or the back of the door? Or was that for the window gasket?
Fiberglass gasketing looks doable. Still need to take a look at some commercial doors to get an idea of construction details, that's probably not going to happen for a week or so.
02-01-2008, 08:33 PM
I built some fireplace doors many years ago and just used some 16ga steel on angle-iron frame. The doors were just strips of wide 1/8" strap welded to lengths of 3/16" angle iron on the backside to make a frame (kind of a makeshift T cross-section) which was very stiff and framed the glass in from the back. I used fiberglass strap to seal around the glass and separate it from the frame.
For the glass I just used two from a stack of similarly sized 1/4" tempered glass that I found for cheap somewhere. I thought having a stack would be handy because I figured it would break from time to time and I had replacements handy, but I used it for four years and never had one break or any other problems - other than having to clean the firebox side of the glass every few days if I wanted to see the fire. The soot cleans off easily.
The doors were mounted to a box I made that extended the front of the opening out into the room another 8" or so, which helped to transfer more heat into the house. Basically it worked nearly as well as any decent wood stove I ever used as far as heat transfer. The box was jut made of some thick sheet metal (about 1/16" thick - or is that thin plate). Anyways, it was all very durable and I made it so if you closed it all up it would choke a fire out.
The impetus behind my "extension doors" was that the flue didn't draw well at all trying to have an open fireplace and smoked up the house badly every time, but this door cover was the ticket. It worked very well.
I know this isn't Mr. Safety & Science's optimum setup, but it worked very well for me. I talked with a friend about using Pyrex lids for the glass if the tempered glass was problematic, but that didn't become necessary.
If you have the money there are certainly safer ways to go, but in that case you might as well just turn the thermostat up ;) I was really broke back in those days but I was really familiar with burning firewood and was prepared with other safety measures in case something went wrong. It was a good solution for me.