I get good results with a plain old slow cooker. The low setting is between 190F and 200F or so. Not ideal but works well enough for me. There is a warm setting

I get good results with a plain old slow cooker. The low setting is between 190F and 200F or so. Not ideal but works well enough for me. There is a warm setting but that's lower than 170F. Ideally they should really have a simmer setting at exactly 175F-185F like you said.