How do you measure stack temp on double wall?

I had single wall pipe for years and had a magnetic thermometer on the pipe. When I bought the new stove, I had everything upgraded to double wall and abandoned the thermometer.
How do measure stack temp. on double wall?

 

Probe thermometer.

 

Does the probe go all the way through to the interior or just through the first wall? Source please.
Any real advantage to measuring the temp?
With my old setup, I had to be burning pretty heavy to get to the green part of the thermometer.

 

Like papadave says, probe thermometer. No guesswork, you know the actual flue temps. They do help for settling in/air shut down, as in my experience, the fire is hotter than it looks and you won't have a fire get away on you, as you shut the air down by temp, not by look.

For example, I just reloaded for a long-ish burn, -25 C and some wind. Side of stove says 250 F probe is at 400 , and air is 3/4 throttled back already. The fire doesn't look very impressive, it looks like a top down. But it will pull and pull until I throttle back the air again. Without the probe, and just give 'er until it looks right, I'll see crazy temps and blow half my heat up the chimney. Sure, it'll be a great looking fire, but I'm trying to use the heat.

Just like bacon in a pan, by the time it looks perfect you've went too far.

 

Many places that sell the mag type thermometers have the probe type too...that said, I bought one of these at Lehmans Hardware just because it was the closest place that had them at the time.
FlueGard Stovepipe Probe Thermometer with Temperature Zones | WoodlandDirect.com: Wood Stove Accessories, Condar

 

This. It works great.

 

Thanks Dave. I am going up home Friday to pick Mom up for Christmas. I will have to stop in at Lehmans and check them out. I also have to stop at 3-D Meats, in Dalton, and get some more beef bacon. Yum.

 

No skimping! Seriously though I want to put this probe in myself but where? How far away from the stove itself up the pipe?

 

You generally want it 18” plus up from the stove top. Installation requires drilling a hole and sticking it in. It is easier with sharp bits and if you make a small pilot hole and then drill to probe size. A super easy and quick project that can be done while the stove is running or not.

Also, FWIW, I would suggest a probe over the magnet mount for single wall as well. For a couple bucks extra and 5 minutes including fetching tools and putting them away, you get a more direct read on the actual clue temps.

 

Check this thread out

High Temperature Alarm?

 

Either a probe thermometer, or even better IMO, a thermocouple stuck just past 1/2 into the inside pipe. The thermocouple will read accurately and instantly and is far more useful than a thermometer, which takes minutes to respond and then usually fibs at least a little.

Brian

 

I'm using a wireless remote BBQ thermometer on my wood furnace downstairs...it is a 2 probe model, I monitor the flue temp and the supply duct temp from my recliner this way. You can set up high and low alarms too...which I love having since I bring the monitor in the bedroom with me when sleeping...something crazy happens, I get an alarm. I have it running 24/7 all winter...batterys last over a year. This is the one I have...
maverick et 732 | eBay