The temperatures on the "slow cooking" or "stew" or "soup" settings and the "warm" setting are:
Slow/ or Soup: Brings contents to a boil (212 F) then down to a "simmer" (smaller bubbles): 190 F
Warm: 160 F
There are different ways of cooking broth, and different recommendations and methods for doing so. Officially, VitaClay's broth recipe is only about 4 hours.
Personally, I'll tell you what I do.
I make bone broth on a weekly basis so I can keep it in the fridge and use it in everything. I use both the multi-cooker (VM7900 series) and the stock pot (VM7800) to do this (one or the other, depending on the size batch I am making).
I fill the cooker with bones, scraps and water to the brim.
I set the cooker to the longest possible cooking time for that cooker on the slow/soup setting (for the stock pot it's 9.5 hours, for the multi-cooker it's 4.9 hrs)
I let it cook all day or all night. When the cooking cycle is finished, it reverts to the "warm" setting, 160 F.
If I'm sleeping or not home it will sit on warm for a few hours.
I come back and start the cooking process again, same as above.
I repeat this cycle until 24 hours has elapsed.
If i'm using chicken bones, at this point I can crush the bones in one hand, so I know the bones are spent. I strain the liquid and feed the bones to my dog.
This alternating method works well for me and I've been doing it for years. Depending on the type of bones I use, I get a lot of gelatin (soup bones or chicken carcasses give me tons of gelatin that jellies up in the fridge).
Since the stock pot doesn't seal, I usually have to add water after the first cooking cycle. As I mentioned before, having less water just means more concentrated broth that you can reconstitute with water later. The main thing is not to let the pot go dry completely, so you may need to add water once or twice.
I do hope this helps you and that you will be happy with our cooker. Personally, I've been using VitaClay for about 10 years. I think it's the safest thing on the market and it literally makes every meal (even broth) taste better.