Buckley Rumford Fireplaces
Jeff Lockhart

Jeffrey Lockhart

Hello Jim,

Eight years since I asked my last question (see text below). I continue to enjoy my Rumford - the best feature of our home.

I know you are busy, but wanted to tell you of an experiment I tried which is so far working out. It's ok if you are unable to reply.

My Rumford was build with the air intake in the middle of the floor in order to meet code. Of course, it was not usable due to its location, and I understand that Rumfords draw air at the top anyway. But since I like to tinker, I kept experimenting with ways to try and use it in some way. A few weeks ago I cut out a piece of aluminum the same dimensions as the floor (36"/18"/13.5"/18") and raised it aprox. 4" with some bricks. I then built the fire on the raised platform, and opened the air intake below, so that fresh air came in, but without it blowing directly on the fire. I then monitored the air temperature in the house from 4 locations, to see if any part of the house became colder as a result of cold air being brought in through other vents (eg. fan exhausts, HRV ducts, etc.). I monitored for three hours; there was no drop in temperature anywhere, and the inglenook where the fireplace sits increased in temperature by 15 degrees (it was a fairly modest fire). There was also no smoke as a result of bringing the air in at the bottom.

This leads me to believe that the fresh air, brought in from below, comes into the room in front of the fire, and mixes in with the air that the Rumford takes in at the throat. If it continues to work I may have something permanent made, perhaps only a couple of inches above the floor.

Jeff Lockhart

Date: Fri, 14 Mar 2003
From: Jeff Lockhart
Subject: Re: Test
To: Jim Buckley


It's a 36 x 36 Rumford that my mason built from superior clay components. (You may not have realized that I'm the same guy that sent you measurements to get an estimate on the steel doors with a frame a few days ago.)

The fireplace is 24" deep, and the firebox is 14" deep, so there's about 10" of masonry at the back. Yes, the 415 degrees was front of the firebox, measured 2' up from the bottom. The temperature of the firebox would have varied greatly depending on whether I moved a few inches up or down. (My logs were shorter- 18 -20", so the fire was smaller than it could have been with 24-30" logs.)

I've attached a crude drawing of the fireplace- it's not to scale, but the measurements are correct. (If you decide to publish the information, let me know and I'll make a presentable drawing.) The results are yours to use if they are helpful; I'd prefer that, since I'm not an engineer, it was pointed out that it was done by an amateur homeowner.

Thanks for the correspondance- this is really interesting. When I think that I almost didn't get a Rumford, but something with closed-off doors & a blower! Our house has radiant floor heat, and I think that the combination is perfect. We keep it cooler (67-70 degrees), so that our nightly fires are pleasant. It is because of those fires that I am a little saddened at the ending of winter.

I'll await the info on the firestopping, and the estimate on the doors.




Here's the info on the laser heat-measuring device:
It's made by RayTek (800-866-5478). The model I used
is called the Rayngr ST. Prices  vary according to how
far away an accurate measurement can be taken.


--- Jim Buckley  wrote:
> Jeff,
> That's great, Jeff.  Very interesting.  I'm really
> not surprised but 
> impressed with the increase in wall temperature
> across the room of 
> almost 20 degrees.

> This is a Rumford fireplace right?  What size?  If
> you told me I 
> forgot.  And how thick is the back wall of the
> fireplace?  I assume 
> the temperature that went to 415 degrees was on the
> surface of the 
> fireback.  That's pretty hot, especially if the wall
> is 12" thick.  I 
> guess it would help me to see a diagram of the
> fireplace and wall 
> with the location of each temperature reading. 
> Maybe pictures of 
> your set up if you took any.
> I think you've done a good job, Jeff.  Are you an
> engineer or 
> scientist?  And can I share your results or publish
> them on the 
> website?
> I think the wording in the code about fire blocking
> is intended to 
> allow drywall to abut the masonry.  I'll check since
> it's not clear 
> to me either.
> Best,
> Jim Buckley
> >Jim,
> >
> >The results of my home test are attached. I
> returned
> >the laser to the owner, so I'll have to call him to
> >get a name and a manufacturer.
> >
> >Some of the notable things about the test for me
> was
> >the effect of the thicker masonary (see side of
> >chimney & side of fireplace readings.) I will say
> that
> >after reading the temperature at the back of the
> >firebox, I am glad that I had the mason leave the
> 4"
> >clearance between the masonry and the back wall.
> U.S.
> >Gypsum states that "the maximum continued
> temperature
> >at which wallboard can be exposed is 125 F."
> >
> >On the performance end, the temperature reading of
> the
> >sheetrock wall which faces the fireplace from 10.5'
> >away validates the radiant effect of the rumford
> >design.
> >
> >I suppose to test it under a worst case scenario,
> >someone would have to have reproduce an actual
> chimney
> >fire, and take measurements of that. I'll let
> someone
> >else do that.
> >
> >Regarding code, there's a passage on your web site
> >that I'm having trouble decoding:
> >
> >R1001.12 Fireplace fire blocking. ...The fire
> blocking
> >of spaces between wood joists, beams or headers
> shall
> >be to a depth of 1 inch (25mm) and shall only be
> >placed on strips of metal or metal lath laid across
> >the spaces between combustible material and the
> >chimney.
> >
> >What shall be place on the metal to a depth of one
> >inch? Are they talking mortar? Fiberglass with
> paper
> >removed? And is 1 inch a minimum or maximum?
> >
> >Anyway, hope the measurements are useful.
> >
> >Regards,
> >
> >Jeff
> >
> >PS Let me know when you have the estimate for the
> >metal door with the frame that we discussed.
> >
> >
> >
> >--- Jim Buckley  wrote:
> >>  Jeff,
> >>
> >>  I look forward to seeing your results.  You may
> be
> >>  able to add
> >>  significantly to the "science" of it all.
> >>
> >>  I've seen and used radiant thermometers but they
> had
> >>  no lasers.  They
> >>  just measured surface temperature deduced from
> the
> >>  wave length of the
> >>  radiation.  How does you gysmo work?  Can you
> >>  provide any more
> >>  information or a manufacture's name?
> >>
> >>  Best,
> >>  Jim Buckley
> >>
> >>
> >>  >Jim,
> >>  >
> >>  >I borrowed an instrument from a HVAC
> contractor,
> >>  which
> >>  >has a laser which one can point at an object &
> get
> >>  a
> >>  >temperature reading. I'm using it to locate the
> >>  tubing
> >>  >in my radiant floor slab, in order to insert a
> >>  >thermostat probe, but I also pointed it at my
> >>  >fireplace, and realized that I can use it to
> >>  determine
> >>  >the temperature at any given point.
> >>  >
> >>  >My indoor fireplace and chimney is still
> unfaced
> >>  >concrete block, so I'm going to burn  a fire
> >>  >throughout the day, and take temperature
> readings
> >>  of
> >>  >various points of the structure: sides & back
> of
> >>  >firebox & chimney, etc. After reading the
> >>  >correspondance between yourself & the various
> fire
> >>  >code officials, I'm really curious (or I should
> >>  say,
> >>  >after looking over my mason's shoulder to make
> sure
> >>  >that the fireplace had all of the proper
> clearances
> >>  to
> >>  >combustibles, and now being stuck with trying
> to
> >>  >figure out how to close them off.)
> >>  >
> >>  >Anyway, I'll send you the readings after I get
> >>  them.
> >>  >
> >>  >Jeff

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