Too Hot ... or ... Not Hot Enough

[larsmith]

This is a question of diminishing returns ...

I've got about 1300 lbs of firebrick in my heater, plus a 6" slab ... and the 1st foot of heater is bermed round about with sand. If you were to check my video, you'd see the feed tube ... the sand / clay is birmed ( burmed ? ) up to that level there and a bit higher on the rest of the heater.

I'm wondering at what point I've passed the brick's ability to absorb the heat ...

or

More importantly, at what point am I just pouring heat up the chimney ?

I expect that cold brick absorbs heat faster than warm / hot brick and suspect that there comes a point where I'm producing heat faster than the brick / cob can absorb it. Is this true ?

What I'm trying to determine is ... how long should I be firing my heater before closing it down ?

Or how can I determine when I should be closing it down & living off the heat it puts out ?

As you can see here, I'm struggling to ask one question and am wording it different ways ... sorry for any redundancy !!

For you people who have rockets and who're enduring temps well below freezing, do you run your heaters all day long ?

I'm hoping that people with experience with the more traditional refractory / masonry heaters might be able to help out here.

[peterberg]

Jan 1, 2009 6:03:34 GMT -8 larsmith said:

Or how can I determine when I should be closing it down & living off the heat it puts out ?

Stone-like material is able to absorb a surprisingly large amount of heat.
I understand you do use a thermometer to measure the chimney temp. The moment when the end temp is rising sharply, it is time to close the stove down. Say, normal temp is between 200 and 300 F, but the thermometer give readings of 500 F. Let the fire die out and start again, when necessary, 3 or 4 hours later.

[larsmith]

TY for your reply.

Is there a thermometer I could purchase ( which won't break the bank ) which perhaps has an alarm on it ?

Or a thermometer for which I could place a sensor on the chimney and mount the digital read-out on a wall somewhere ? Perhaps a "remote" thermometer ?

[Teach]

Larsmith, Lyman products produce a thermometer that is used for lead casting in the home made making of bullets for firearms. It's temperature measures up to 1000 degrees F. It would not be good for internal stove temps but for exhaust gasses should be fine in that range. It looks like a glorified meat thermometer with a large dial face that is easy to read. Failing that; Canadian Scientific has all kinds of heat measuring equipment. You could look them up too.

www.lymanproducts.com/lyman/bullet-casting/casting-thermometer.php