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Using cooktop temp to engage cat on PH?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Slow1, Nov 4, 2012.

  1. Slow1

    Slow1 Minister of Fire

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    So we all know that the stone lags the cat temp quite a bit and it seems using the single wall pipe as a guide is better so you can engage faster, but for those of us with double wall, might lifting the center stone and using the griddle below as the guide be a good idea?

    What I'm thinking is that if I'm doing a cold start then just lift the center stone and fire up until the IR thermometer pointed at center of griddle hits xxx degrees and engage cat, then lower the stone and be done with it.

    Has anyone tried this and if so, what temperature have you found works well?

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  2. Backwoods Savage

    Backwoods Savage Minister of Fire

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    But what xxx degrees would you go? I'd suggest checking with Woodstock to see if they have experimented doing this. Personally, I'd be happy to continue using the stone temperature and engage perhaps at 200 -225 with the steel cat.
  3. Buck1200

    Buck1200 Member

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    I've been engaging with the top stone reading around 150-ish and the flue temp (double wall pipe with Condor flue probe) at around 300-350 and getting light-off every time. Cat temp is always in the high 700's to 850 range depending on the size of the load by this point (I have a thermocouple on the cat output, so I can see what's happening). The cook top definitely lags compared with the prior solid stone top. This only matters during start-up, however.

    I always leave the air on full for another couple of minutes in order to let everything get hot before shutting down. The cat temp always drops 50-75degrees as soon as the bypass closes, as the casting behind the cat now has to heat up, but starts rocketing back up with in 15 seconds or so.
  4. chipsoflyin

    chipsoflyin Member

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    buck, what is the max temp your seeing on the cat probe.
  5. raybonz

    raybonz Minister of Fire

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    Just wondering what you think about the steel cat so far Dennis.. Do you like it better than the ceramic cat?

    Ray
  6. Buck1200

    Buck1200 Member

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    With firebox flames it's usually in the high 700's. Without, it will be high 900's minimum during the early stage of the burn, an as far north as 1400F depending on how large the wood charge is. The transition from 700's to 900's with and without flames is usually within 30 seconds or so.
  7. chipsoflyin

    chipsoflyin Member

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    I get nothing like that. 700 early, 900-1000 peak. Having a cat probe makes takes all the guess work out of it. You know instantly what's going on. For anyone that wants to set their own up, omega engineering sells a k type thermocouple with ceramic insulated lead wire and an air hood for 30.00. Connect that to a simple 30.00 eBay temp display, route the wire in through the upper rear hole (there is a bolt there from the factory), position the thermocouple in the middle of the air stream directly above the cat and you,are,off and running. Instantaneous response and and doesn't shut off after 5 minutes like the condor.
  8. tcassavaugh

    tcassavaugh Minister of Fire

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    +1 on the cat probe. used to have one in my Consolidated DW was easy to tell when to throw the bypass and if the cat was working.

    cass
  9. Backwoods Savage

    Backwoods Savage Minister of Fire

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    We like it a lot and it only will depend upon the lifetime of the cat whether it is best or not. They are still experimenting at Woodstock.
  10. tcassavaugh

    tcassavaugh Minister of Fire

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    i used a steel one in my CDW for awhile, it didn't seem to do well for me. went back to the ceramic cat as it seemed to work better.....for me anyway.

    cass
  11. chipsoflyin

    chipsoflyin Member

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    I'd like to see a ceramic option for the PH
  12. 3fordasho

    3fordasho Feeling the Heat

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    Chipsoflyin - care to share a few more details on the k-type thermocouple you're using? I find several selections on omega's site, all in the $30 range. Do you have the Omega part number handy?
    Much appreciated...


  13. fire_man

    fire_man Minister of Fire

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    Chips - where exactly is that bolt? I wonder if the original Progress did not have it?
  14. chipsoflyin

    chipsoflyin Member

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    This one is on eBay, I did have to modify the cheepo eBay display to accept the standard k type plug(ostw). the display came setup for a k type mini plug. OmegA has the correct plug (part number xcib -k-5-6-10) but they want 65.00. http://www.ebay.com/itm/Omega-High-...-K-with-air-hood-XCIB-K-5-2-10-/320942003648?
    pt=LH_DefaultDomain_0&hash=item4ab9a255c0

    The display can be had from eBay, just search for k type thermocouple thermometer. For a few bucks more you can get into a multimeter, another option is to look at temperature controllers, with that you could set up an alarm/data logger


    Fireman, I have one of the early stoves, and on mine it is on the upper rear just under the top lip on the door side
  15. fire_man

    fire_man Minister of Fire

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    çhipsoflyin: Thanks I see the bolt. I would have never guessed that was for a Cat probe. I may just have to look into the Thermocouple now. Great, one more gadget!
    raybonz likes this.
  16. binko

    binko Member

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    I called the Woodstock folks today about where to install the probe in the PH and they told me about a hole in the back with a 1/4'- 20 screw hole.
    I then contacted Omega and they told me that they do not have a compression fitting to match that. How have others mounted their thermocouples please?
  17. Buck1200

    Buck1200 Member

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    I just stuffed pieces of fiberglass rope in the hole after running the thermocouples out (inconel sheathed 1/16" diameter type K). I thought about drilling out a bolt to slip the tc through- perhaps I still will. It would look prettier, anyway.
  18. chipsoflyin

    chipsoflyin Member

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    a little dab of furnace cement took care of the hole. when it comes time to c/o the thermocouple the cement should flake right off.
  19. chipsoflyin

    chipsoflyin Member

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    it never ends
  20. 3fordasho

    3fordasho Feeling the Heat

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    Thanks for the details - think I'll buy two of everything, one for the progress, other for the fireview ;-)


  21. Slow1

    Slow1 Minister of Fire

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    Ok - all you folks inserting these probes in the PH - how about some pictures eh? i.e. showing placement of the probe internally etc?
    raybonz and rideau like this.
  22. chipsoflyin

    chipsoflyin Member

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    IMG_0024.JPG


    heres one directly in the middle of the cat
    raybonz likes this.
  23. Buck1200

    Buck1200 Member

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    thermocouples.jpg

    The vertical tc measures the cat outlet temp and the angled one actually dives through the cat to measure the upstream temp. I also have one over on the left edge of the cat looking at the variation in face temps (found to be insignificant).
  24. fire_man

    fire_man Minister of Fire

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    Perfect pictures, Buck1200, thanks for posting. So what sort of differential temps (upstream vs outlet) are you seeing after the cat lights off? I seem to remember WS saying it was 300F.
  25. Buck1200

    Buck1200 Member

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    That depends on what's happening in the firebox. With lot's of flame the vast majority of volitile gasses are burned there, so the cat doesn't do much and may show only a 50 degree rise, or none at all. 300 is generally a good average. Honestly, the battery died in the precat meter last winter and I haven't replaced it yet. It's the post cat tc (that meter is on AC power) and the flue temp which tells you everything you need with this stove. As long as the flue temp is 300 to 350 and the post cat temp is in the high 700's it will light just fine. The stove top can be as low as 150 with the new cook top depending on if the stove was started from cold. I would never tell a person to close the damper at a 150 stove top temp however, without knowing the cat and flue temps.

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