thermocouples... same o same o

[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.

[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.

[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.

[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

[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.

[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

[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?

[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 $$ and get a cheaper meter and then just swap plugs. Swapping plugs only takes an extra 5 seconds. I bought the hand held digital meter that takes 2 K-type inputs for about $75. If I were to do again, I would buy the combo IR gun that also reads K-type TC's and have the capability to do both in one and spend less $$.

[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....

[jcg31]

Re: thermocouples... one more time

Sorry to put you guys through this again, but I have flipped on the thermocouple issue and am now contemplating it once again. I have searched all the posts and get the fact that I should be looking at K type thermocouple, but I don't see much out there on a preferred display. I would be looking for a wall mount (that I would enclose using CJim's approach) with four inputs, data tracking would be cool so a port out would be great but not essential. Anyone have any preferences?

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?

Thanks for any help,

Jim

[ricocamus]

Re: thermocouples... same o same o

Rico,

Depends entirely on what type and how much cooking or baking your want to do. For a pizza bake of an hour or so, surface temps are all you need. If, however, you want multiple bakes, or you have added additional mass for heat retention over time, then deep brick or mass temps are very important. My oven is high mass, and I do multiple bread bakes over six to ten hours, so mass temps are just as important as surface temps. Next, when the mass has dropped to acceptable levels, I'll put in the roast or the chicken or the....

Jim

Hmmm, getting more complicated but more interesting as well. Now I think I have one more item to add to the buy list.

Is it just me or do these projects really have a way of growing on their own. Sort of like pizza dough in the rise stage . . .

[CanuckJim]

Re: thermocouples... same o same o

Rico,

Depends entirely on what type and how much cooking or baking your want to do. For a pizza bake of an hour or so, surface temps are all you need. If, however, you want multiple bakes, or you have added additional mass for heat retention over time, then deep brick or mass temps are very important. My oven is high mass, and I do multiple bread bakes over six to ten hours, so mass temps are just as important as surface temps. Next, when the mass has dropped to acceptable levels, I'll put in the roast or the chicken or the....

Jim

[ricocamus]

Re: thermocouples... same o same o

A brick wall that's hot most of the way through will stay hot and radiate heat for a long time. One that's hot on the surface will cool down quickly.

OK, think I am beginning to understand.

The objective, then, is to get high temp (900) on the surface and in the brick. If you do that, then you can bake pizza all night long! Because the hot bricks will keep the surface temperatures hot.

[dmun]

Re: thermocouples... same o same o

A brick wall that's hot most of the way through will stay hot and radiate heat for a long time. One that's hot on the surface will cool down quickly.

[ricocamus]

Re: thermocouples... same o same o

Yeah, who is that guy? Masked man, likely. Anyhow, my thermos are rated at 1000 F, but I've had them reading as high as 1050 with no ill effects. Usually, the floor reading is in the 900 range before I let the oven moderate. As I see it, the real difference is that thermocouples will give you reliable temps at various spots in the brick and any additional mass. The guns will supply surface temps, but they won't say if the brick and mass have been saturated.

Jim

Thanks for the enlightenment on what the thermometers will do.

Now, for another 'serf' question - why do we need to know if the brick has been saturated? Isn't the surface temperature what counts for cooking?