Is this modification a bad idea?

[geofox784]

I would like to add a thermocouple flue thermometer to my zero clearance fireplace, an Osburn Stratford II, probably with the Auber SYL-2813AC meter since it has a second input I can use to monitor the firebox temp. However, I can't add it to the chimney pipe since it won't be accessible once the fireplace is fully installed. I'd like to keep it accessible so it can be removed for chimney cleaning and replaced if it ever breaks.

Easily accessible from the front of the fireplace is the internal flue pipe. It has an 8" OD while the flue is only 6", so there must be either a 1" air gap or 1" of insulation between the outer wall and the inner flue pipe.

Any issues with drilling a small hole here to install the thermometer? It is only about a foot above the baffle instead of the usual foot or two up the flue pipe.

 

[guylavoie]

That sounds like a bad idea. At minimum, it will likely negate the UL and any other approvals of your fireplace.

 

[geofox784]

That sounds like a bad idea. At minimum, it will likely negate the UL and any other approvals of your fireplace.

Wouldn’t penetrating the chimney pipe also void the UL, yet people do that all the time?

 

[bholler]

Wouldn’t penetrating the chimney pipe also void the UL, yet people do that all the time?

People don't penetrate the chimney pipe often at all. But if I had to choose I would drill the pipe.

 

[begreen]

+1 for the chimney pipe. There is no need for noting the firebox temp. That would require drilling a hole in the stove unless this refers to the top of thes stove's surface temperature. Even then, it's not really necessary. FWIW, I run the stove by flue temp and rarely look at the stove top temp unless I am cooking on it.

 

[geofox784]

+1 for the chimney pipe. There is no need for noting the firebox temp. That would require drilling a hole in the stove unless this refers to the top of thes stove's surface temperature. Even then, it's not really necessary. FWIW, I run the stove by flue temp and rarely look at the stove top temp unless I am cooking on it.

Sorry not firebox temp, stove top temp.

Unfortunately I won’t have access to the chimney pipe so I won’t ever be able to remove the probe for cleaning, if it breaks, etc. Hence my interest in installing it before it fully exits the fireplace and is still accessible from the front.

 

[EbS-P]

Sorry not firebox temp, stove top temp.

Unfortunately I won’t have access to the chimney pipe so I won’t ever be able to remove the probe for cleaning, if it breaks, etc. Hence my interest in installing it before it fully exits the fireplace and is still accessible from the front.

Odds are someone breakers it off. I’d just insert it just an inch. That good enough to get a reading and not enough to get hung up on a rotary cleaner. It would need a brackets to hold it in place at that different insertion depth

 

[begreen]

Do you have an IR thermometer? If so, take readings off of the spot on the internal flue pipe during various stages of a full load burn and wrtie them down. See if they provide sufficient guidance.

Or, would it be possible to put an inspection hatch or access door on the chase for access to the probe when cleaning?

 

[geofox784]

Do you have an IR thermometer? If so, take readings off of the spot on the internal flue pipe during various stages of a full load burn and wrtie them down. See if they provide sufficient guidance.

Or, would it be possible to put an inspection hatch or access door on the chase for access to the probe when cleaning?

I've got better that that

The top of the fire box, which I assume would be equivalent to the "stove top" temp, is much hotter than the insulated chimney pipe above it, so there would be no benefit to the thermometer on the outside of it.

It wouldn't be terribly difficult to build an invisible small access hole in the stacked stone I plan on using for the front. However, if it is unacceptable to drill a small probe hole in the chimney within the fireplace is it acceptable to drill a hole in the class A chimney pipe? Most of the examples I see are in double wall stove pipe instead of class A chimney pipe.

 

[begreen]

It's your fireplace and your option. The FLIR reading Sp3 looks useful. but better just a tad higher near the flue stack (in the yellow area). It looks a surface thermocouple placed right up against the internal flue pipe would provide a usable reading. This may be all that's needed.

The slit above Sp4 also looks like it might have potential for nesting a surface probe.