Double Wall Flue Thermometer

[soupy1957]

The Flue Thermometer came in today. It has a washer and a magnet on it.

I presume that both the washer and magnet end up between the thermometer face and the outside flue pipe, but there was something on the packaging about which one you put first, and I THINK I recall it saying that you put the magnet first, and then the washer, before installing the probe into the flue pipe…..........that sound right? Why use the washer at ALL?

They want a 3/16” hole in the inner wall, and a .250 (quarter inch) hole in the OUTER wall.

I'm gonna measure a minimum of 18" off the top of the stove for the installation, and use a prick punch to set a spot for the drill (anyone who has ever tried drilling a hole into a radius'd piece of material, knows that the drill will "walk" otherwise).

Made sense to go thru both walls with the 3/16" drill first, and use the outside hole as a pilot hole for the .250.

-soupy1957

 

[Battenkiller]

there was something on the packaging about which one you put first, and I THINK I recall it saying that you put the magnet first, and then the washer, before installing the probe into the flue pipe…..........that sound right?

Pays to save the packaging. :cheese:

Making a good punch mark on double-wall pipe may not be easy since there is no way to back up the outer wall with something solid. You should have no problem with drill bit wander on 6" pipe if you step-drill, starting with a sharp 1/16" bit in a high speed drill.

 

[firefighterjake]

The Flue Thermometer came in today. It has a washer and a magnet on it.

I presume that both the washer and magnet end up between the thermometer face and the outside flue pipe, but there was something on the packaging about which one you put first, and I THINK I recall it saying that you put the magnet first, and then the washer, before installing the probe into the flue pipe…..........that sound right? Why use the washer at ALL?

They want a 3/16” hole in the inner wall, and a .250 (quarter inch) hole in the OUTER wall.

I'm gonna measure a minimum of 18" off the top of the stove for the installation, and use a prick punch to set a spot for the drill (anyone who has ever tried drilling a hole into a radius'd piece of material, knows that the drill will "walk" otherwise).

Made sense to go thru both walls with the 3/16" drill first, and use the outside hole as a pilot hole for the .250.

-soupy1957

I think you've got the right order . . . I think I just followed the directions and looked at the picture on the back of the package . . . or maybe I just figured that was the way to mount it. I'm not really sure why there is the washer . . . it was included so I kept it.

 

[Todd]

When I use to have mine I had the magnet first right up against the pipe followed by the washer. Pretty sure that's how it goes but you could always call Condar and double check. I'm thinking the washer is there to block some of the radiant heat to get a more accurate internal temp? Good idea on the punch, I found out the hard way and my hole ended up a little off center.

 

[DAKSY]

Center punch it first - can't hurt. The biggest trick to drill thru pipe is holding the tool perpendicular to the workpiece.
That will minimize any "walking."
Instead of 2 drills, you could use something like this:
http://www.craftsman.com/shc/s/p_10...ord=step+drill&prdNo=4&blockNo=4&blockType=L4
Pricy, yes, but I'm an " I gotta get me one of these!" kinda guys...

Does the magnet have a radius on one side of it?

 

[Battenkiller]

Instead of 2 drills, you could use something like this:
http://www.craftsman.com/shc/s/p_10...ord=step+drill&prdNo=4&blockNo=4&blockType=L4

Those things are great. They actually ream the hole, so you get a cleaner hole. Plus, they're tapered so you can get a real tight fit by just going deep enough at each step for the purpose required. I think I've seen them a lot cheaper from machinery supply houses. Thanks for the reminder, I gotta get me one of those next order.

 

[charly]

Harbor Freight, you can get three of those step drills for under 20 bucks. I've drilled 3/16th steel angle with them and they worked good. For double wall pipe , you'd have to use a straight drill bit for the final size hole. Step drill would leave you with a bigger outter hole.

 

[ANeat]

I just drilled the 3/16 first, then opened up the outside hole.

Mine (Condar) came with a small eyelet if thats what youre refering to as the washer, I put that into the 1/4 drilled hole, then the magnet, then the thermometer.

I think it doesent matter to much which order, the main thing is to get the probe in the hole right???

 

[Battenkiller]

I think it doesent matter to much which order, the main thing is to get the probe in the hole right???

That's been my primary concern since my teens.

 

[charly]

Found Bacarach 0012-7014 Tempoint probes for $69.35, on sale. Usually 80-90 dollars . Bought one for my new woodstove install. Had one on my Paxo 60 gasifiaction boiler at my house I just sold. Nice looking units, can be recalibrated in boiling water to check accuracy, if needed. They come with a nice clip, that hangs in a 1/4 inch pipe hole you drill. You then insert the gauge into the bracket that's already mounted into the pipe hole. Stays put and doesn't move. WWW.Tequipment.Net is where I got the probe. No picture on the site. Just put in Bacharach 0012-7014 Tempoint Thermometer, it will bring up a site with a picture. Nice big easy to read dial face. Just in case anyone's interested. These normally come in a oil furnace testing kit.

 

[soupy1957]

Don't have the magnet in front of me at the moment, so I can't say whether or not it has a taper on one end or not. I'll check later......I'm assuming the taper should be either facing the flue or facing the thermometer, but I don't know which.

The washer in this set up is too big for a 1/4 hole (Washer is probably Ø.650, by MY eye).

Makes sense that the washer should be next to the thermometer, to reduce the heat transfer to the thermometer itself, but I'm wondering if the washer would then inhibit the "holding" factor of the thermometer against the magnet, against the hole?

-Soupy1957

 

[charly]

The washer might be there to help keep the magnetism in the magnet, since it is exposed to the heat.

 

[CJRages]

I'm having a hard time visualizing all this. Does anyone have a picture of one of these thermometers being installed? That would help a lot. Thanks!

 

[charly]

You drill a 1/4 inch hole,.250 thousandths, in your pipe, and put the probe into the hole. Simple. Like checking meat with a thermometer. Old school simple.

 

[soupy1957]

I'm afraid I can't agree with xclimber's instructions completely. Yes, it does require a 1/4 inch hole in the outside pipe, but on the interior pipe wall the product requires a 3/16" hole as well.

I'm being sorta gun shy about the installation, and am almost talking myself out of it at the moment. I don't want to introduce a hole to my system that, if the thermometer sags over time (I actually read about some "sagging" experiences in here), now I have a hole that is a compromise to the system (sorta like the oil well that needed capping) and then I'll have a situation where the gases from the pipe can leak in between the two walls of my flue pipe, warming the outer pipe, and creating a heat issue. Suddenly, due to heat increases, I'm not only running the risk of being too close to exterior surfaces with an outer wall that is now as hot as my inner wall, but I'm also creating air flow either in or out of the system, in a place where you DON'T want that to happen.

Either I'd be introducing air "in" altering my draft conditions, or "out" bringing smoke in between my two layers of pipe, and potentially into the house. Increasing the risk of CM poisoning.

These are the arguments of a worried wife..........I'm spewing them out, here, so that ya'll can see what I'm up against.

-Soupy1957

 

[charly]

Soupy,
Why don't you just start with a small drill bit, work up to a 3/16th bit for both holes and then finally , just go easy with a 1/4 in. bit for the very outside hole? I like the Bacharach Thermometer Probe, as it comes with a little gauge support clip. You hang the clip , into the hole you just drilled, and then the gauge probe slides thru the clip into your pipe. The clip keeps it from sagging, and also keeps the gauge from spinning around . Nice solid set up. But 69 dollars verses 26 dollars. It also has a larger dial face, about two and a half inches.

 

[oldspark]

The gases will not leak back into the pipe as the draft takes care of that, follow the directions that came with it and you will be fine.

 

[ANeat]

The gases will not leak back into the pipe as the draft takes care of that, follow the directions that came with it and you will be fine.

+1, the pipe should have negative pressure when in use (sucking)

If youre worried about what effect the hole has on the draft, well first the hole is "plugged" with the thermometer.

Second, even if you removed the thermometer and left the hole open its only a .1875 hole compared to a 6" hole in the flue pipe.

Thats .110 sq inch compared to 28+ sq inches or to put it another way the area of the thermometer hole is only .031% of the area of a 6" flue

 

[soupy1957]

.187 on the inside....... But .250 on the outer wall. I get your point though. What was all the hubub about in here (in other threads) about a "sagging" of the thermometer? What caused that for them? How do I avoid that?

-soupy1957

 

[ANeat]

I havent seen anything on sagging thermometers, I even searched and nothing came up except this thread

 

[vvvv]

Has anyone figured out if theres a useable correlation between the outer surface of the double wall to the fluegas temperatures?

 

[begreen]

I havent seen anything on sagging thermometers, I even searched and nothing came up except this thread

Sagging candles - yes. Sagging jowls, yep. Sagging thermometers? Only on Salvador Dali's stoves.

 

[Wood Heat Stoves]

I havent seen anything on sagging thermometers, I even searched and nothing came up except this thread

Sagging candles - yes. Sagging jowls, yep. Sagging thermometers? Only on Salvador Dali's stoves.

the simple magnet types have been known to demagnetize and fall off hot pipe to melt carpet--fix:use the supplied screw

 

[begreen]

Good point, thanks Dave. That is for the single wall stove pipes, correct? My understanding is that this doesn't apply to soupy's case with a probe thermometer on double-wall pipe.

 

[Battenkiller]

These are the arguments of a worried wife..........I'm spewing them out, here, so that ya'll can see what I'm up against.

Ya, we've all been there. Have her read Old Spark's comment above and get her a nice glass of sherry to relax with. ;-)