Monitoring RMH internal temperature

Hi all;
Not everyone who builds an RMH is interested in the internal temperatures.
Most are in awe of how incredible the efficiency is, and how long their home stays warm with no fire at all.

However, some of us are geeks... we want to know how hot it is inside the RMH.
Why might we want to know this?  As simple as why most vehicles have gauges.
Knowing the "normal" temperature or pressure at which something operates will alert you to impending troubles.
The water temperature in your car's motor suddenly rises, the low oil light comes on... better pull over and check it out before ruining your motor.
If the internal temperatures in your RMH change, something is wrong; you may want to investigate further.
By monitoring these temps, we will know if there is an issue, and can plan for a rocket surgery at a time of our choosing, rather than after something fails mid-winter during mid-burn.
Most RMH operators have a handheld laser temperature gun, which is very useful for monitoring external temperatures.
It will alert them that something is amiss with their RMH.
But with external readings, the issue may not be apparent until it becomes severe enough to require immediate attention.
With the strategic placement of high-temperature probes in the riser, at the top of the bell, and the internal gas temperature inside the exhaust chimney, a range of normal operating temperatures can be observed.

Do these failures happen often?   No, almost never, not with a well-built core and bell.
But, Thomas, you're an experienced builder!
We see post after post from you rebuilding your RMHs multiple times, some with dramatic failures!
Yes, you sure do!  I am an experimental rocket scientist, as well as a hillbilly builder!
I try things, and I know that I will be taking them apart at a later date, sometimes much sooner than expected.
Once you have some experience, this is no big deal at all.
However, with my Shorty core build, I enlisted the calm aid of Canadian rocket scientist Gerry Parent to help and assure things were square and level. (No hillbilly building allowed in Liz's house!)

Of course, some experimental rocket scientists will try to improve their RMH.
However, Peter is the Master experimenter among us all, as the saying goes, "he has been there, and done that."
Using superior testing equipment, any improvements have already been proven and incorporated into his final design.

What is the cost of purchasing and installing these high-temperature probes?
Generally, less than $100
The meter with several mid-temperature probes averages around $50
A ceramic high-temperature type N probe is used inside the riser and costs apx. $30

thomas rubino wrote:Hi all;
Not everyone who builds an RMH is interested in the internal temperatures.
Most are in awe of how incredible the efficiency is, and how long their home stays warm with no fire at all.

However, some of us are geeks... we want to know how hot it is inside the RMH.


What is the cost of purchasing and installing these high-temperature probes?
Generally, less than $100
The meter with several mid-temperature probes averages around $50
A ceramic high-temperature type N probe is used inside the riser and costs apx. $30

Excellent thoughts and I would like to add just a couple more.

1) by knowing  how much heat a load of wood produced, a person can quickly evaluate, if a full load of very light wood such as cotton wood/willow, that is almost free, vs a same size load of oak-hickory that perhaps took double the time to get and store but still free.   Without knowing, one really is guessing. which of course gets more accurate with experince.   But still fun to know.

2) if you have kids old enough to load the stove once or twice a day,  having them notate - time of day, temps and so on, gives them life long lessons, on keeping track of things without the aid of a computer. ( or lets them create a list to put into the computer-Just good old fashion number crunching that seems so foreign to many today)

3) forecasting heat needs- The weather man can get fairly accurate on what tomorrows temp is going to be outside, with probes you can develop temps to match those coming.  It can become fun, working your way to very even temps in your house,  ( yes lots of mass helps- but knowing what the mass temp is, internally, is even more helpful)

4) it is just plain fun!

    Tom, and anyone else, I think this would be a great place to note places that sell and what works best, or even things that seemed to work well but did not last long.    Big kiln operators, rely on  gages that last for years. ( that's a hint)

Cheers all!

Most thermocouple probes for high heat are of the K type and work fine in the interior of your RMH.
A meter for reading K-type probes is readily available at Amazon.
https://www.amazon.com/Proster-Thermocouple-Thermometer-Dual-Channel-Thermocouples/dp/B071V7T6TZ/ref=sr_1_4?sr=8-4
These meters all claim to be compatible with various types of probes, including the N-type.
It has been brought to my attention that this is not entirely true.
A meter for a K-type probe will not give accurate readings for an N-type probe.

Unfortunately, I have discovered that the K-type ceramic high-temperature probes have a problem performing in an oxygen-starved environment.
The K-type probe inside Shorty's riser started failing to read within just a few weeks.
Glenn Littman in Colorado has had the same problem with his K-type probe inside the riser.
Glenn contacted Carston at Minnesota Measurement https://www.meter-depot.com/
He gave us the following information.

In an oxygen-starred environment, a K-type probe will develop "green rot" and stop sending accurate signals to the meter.
An N-type probe has a similar cost to the K-type but can last for many years in a low-oxygen environment.
He informed us that the K-type meter has a different calibration curve and will not read accurately with an N-type probe.
The different alloys used in construction will result in different voltage outputs for the same temperature.
Minnesota instrument's will be carrying an N-Type meter soon.  
A quick search on Amazon failed to locate any meters calibrated for strictly N-type probes.

Despite the claims, the low-priced K-type thermocouples are only useful for reading internal bell temperature and exhaust chimney gas temperature.
Experimental Rocket Scientists who want this information should invest in all N-type temperature probes and a matching N-type meter to obtain the proper readings.