thermocouples... same o same o

[asudavew]

Re: thermocouples... one more time

Also (great timing) my dome is up, so in placing a thermocouple in the floor am I better coming in through the soldier course and floor brick (and how far in do I need to come to be meaningful), or up through the concrete and vermicucrete?
Jim

Great question! I just figured I would go from under the hearth, through the concrete and verm layers...
But it sure would be a lot easier just to go through the side and into the floor bricks.
And I don't know why it wouldnt work, unless you wanted to know the floor temp right in the middle of the floor.
I think I will go through the side....

[wlively]

Re: thermocouples... same o same o

My floor TC is inserted through the side of the floor. I built the dome on top of the floor, so where the edge of the floor was exposed I drilled a 9" hole, pointed at the center of the floor, and put my thermocouple in there. It does not measure the center of the floor, but I do get decent readings which jive with the temp gradient across my dome. I think it is a good compromise in placement, not "the perfect spot" but is easier to install and route wiring.

As for meter. If you want to read multiple TC's at the same time you either have to get a rotary selector switch or a multi-input meter, neither of which is very cheap. You don't really need to see all the temps at the same time. The temp change is moderated by the thermal mass, so it is not very fast. Much easier to save the $$ and get a cheaper meter and then just swap plugs. Swapping plugs only takes an extra 5 seconds. I bought the hand held digital meter that takes 2 K-type inputs for about $75. If I were to do again, I would buy the combo IR gun that also reads K-type TC's and have the capability to do both in one and spend less $$.

[jcg31]

Re: thermocouples... same o same o

As for meter. If you want to read multiple TC's at the same time you either have to get a rotary selector switch or a multi-input meter, neither of which is very cheap. You don't really need to see all the temps at the same time. The temp change is moderated by the thermal mass, so it is not very fast. Much easier to save the $$ and get a cheaper meter and then just swap plugs. Swapping plugs only takes an extra 5 seconds. I bought the hand held digital meter that takes 2 K-type inputs for about $75. If I were to do again, I would buy the combo IR gun that also reads K-type TC's and have the capability to do both in one and spend less $$.

Can you send me some product links? I found this one "technika.com/Sper/s800024.htm". What think ye of this solution?

[asudavew]

Re: thermocouples... same o same o

Hey Wade.

How many thermos do you have, and where did you place them?

I was thinking of putting one in the floor, in the top of the dome, and one all the way through for air temps?

Do I need one for air temps?

Jim,

Here is a link Wade sent me for a nice little unit.
Might want to check it out.

Low Cost Infrared Thermometer with Adjustable Emissivity


I found an older unit that looks brand new on Ebay for under thirty bucks. It is the J-type, but goes up to 1200f. It has one probe that came with it, and I ordered 2 more.
You may want to give Ebay a try.

Dave

[wlively]

Re: thermocouples... same o same o

Can you send me some product links? I found this one "technika.com/Sper/s800024.htm". What think ye of this solution?

Here is what I bought, looks like it went up $10. You can see a picture of it in action on my oven post.
Mini Thermometer ? Moderately Priced - Ideal for Education, Training and Demonstration Programs

The link you posted looks like a fine meter, but unless you have the $$ to burn, or are going to use the oven commercially the extra $$ are not really worth it, IMHO.

As I continue to learn my oven's characteristics, I don't really use the TC's very much anymore. I can now cook pizza by color and feel pretty easily.

[wlively]

Re: thermocouples... same o same o

Dave

I have three. One in the floor, one in the side of the dome about 1/2 way up, and one dead center in the top. All are center of mass, tip of thermocouple in middle of brick.

If you are going to use in the brick, then definitely the floor is one. The other I would put about 3/4 dome, that gives you good guess as to the top of the dome temp as well as lower dome temp. But, nothing really wrong with top of the dome either. If I knew then what I know now, I would have made it easy to open up the enclosure and move TC's around. The times I have charted 15 min temp intervals the spread of temps from the top to the floor has remained constant, so I don't really need all three temps as by reading one I can tell what the others are. Word of context, this may only be true in relatively short pizza firings, as I have not done any really extended multi-day burns.

I plan on doing some baking, smoking, ect, so I will need to buy one more that I plan to mount in my door and project it inside the dome to give air temp. Probably not really neccessary, since the temp of the surface of the brick is pretty much going to be the radiated temp inside the oven, but I want to be able to read the inside temp without opening the door.

Hey Wade.

How many thermos do you have, and where did you place them?

I was thinking of putting one in the floor, in the top of the dome, and one all the way through for air temps?

Do I need one for air temps?

Dave

[Acoma]

Re: thermocouples... same o same o

Wade the wizard should be your name. "As I continue to learn my oven's characteristics, I don't really use the TC's very much anymore. I can now cook pizza by color and feel pretty easily". The sign of one that increases the knowlege by costant use.

[jeff]

Re: thermocouples... same o same o

G'day and thanks again for this site.
Questions: as a Newbie, I need all the help I can get.
No. 1, thermocouples.
Can any Aussies put me on to a local supplier? If not, any Yank cousin game to help out? I can't use this e-bay stuff, and I live in the scrub. Makes it awkward, but I'm not about to go urban.
True, this pompeii oven project is one that I've totally embraced, and would like to make a fair job of the whole shebang.
Also interested in local supplies of waterglass; as well as the effects of metho (de-natured ethanol, for those non-alcoholics among us),as a hardening agent for waterglass/vermiculite mass.
James and Members,
Thank you.
Jeff.

[wlively]

Re: thermocouples... same o same o

Acoma

You are to kind, although I wish you were right. I have some lead in the garage I wish I could turn into gold.

Everything James and other "long timers" have said about gradually learning how to read your oven is true. I bought the TC's because the "geek" in me "had to know" exactly how the brick mass and temperature interact.

[jcg31]

Re: thermocouples... same o same o

One last question, apart from the one that will breach the brick for oven ambient temp, where I imagine I have little choice but to backfill with mortar, should the others (drilled and placed into the brick) be forever mortared in place? or in the interest of possible repair should I just drill a hole, insert probe without filling with mortar?
Thanks,
Jim

[Acoma]

Re: thermocouples... same o same o

Jim, mortered in place I would think. They are mortered on dome areas by cladding, correct? if they get covered by structure, no getting to them then either.

[wlively]

Re: thermocouples... same o same o

Jim

You want very good contact between the TC and the brick to get a good temp reading. Best choice would be to drill a hole the same size as the TC, so that it is a tight fit. Other option would be to drill oversize, fill with mortar and push the TC in and mortar should ooze out. If you go with smooth stainless sheathed TC's the mortar will not stick too well and you should be able to remove it.

One last question, apart from the one that will breach the brick for oven ambient temp, where I imagine I have little choice but to backfill with mortar, should the others (drilled and placed into the brick) be forever mortared in place? or in the interest of possible repair should I just drill a hole, insert probe without filling with mortar?
Thanks,
Jim

[jcg31]

Re: thermocouples... same o same o

OK, reviving this thread one more time, which I used earlier to establish my thorough lack of understanding of the topic. To continue that theme, I received my thermocouple(s) yesterday. I guess I was expecting some sort of sheathing or probe-like end to the wire to insert into mortar/brick. What I received is pictured below (thin wire with tiny metal loop at end). Is this what I need, or do I need to give the folk at omega a bit more direction regarding my requirements?

Thanks for any help.

Jim

[wlively]

Re: thermocouples... same o same o

Jim

While not what you want, it would be possible to use those as is, if the wire covering was rated for high enough temp. But, by the looks of the color code, I would say that probably is not the case. Your best bet is to try and send them back and get something much easier to work with, especially for the unexperienced. You can buy ceramic sheaths to put them in, and make probes and then splice it back together or install connectors, but that would definitely not be for the beginner.

Form a post a while back here are the Omega part numbers I posted.
"I bought these;
Omega part number:
KMQSS-125U-6. 1/8 Stainless sheath 6" K-type with miniature connectors
TECK10-9 10ft extensions."

If they won't take them back, then let me know what you have (part number, how many, ect) and I can try and find the cheapest solution. Don't worry, if needed I can build them for you, provided you trust the post office.

[jcg31]

Re: thermocouples... same o same o

Thanks Wade!
Let me see what they will do and I will get back with you.
Jim