Looking for: Thermometer

I'm looking for an analog/dial type thermometer with a probe 4-6" long or so, and pipe threads on the backside of the dial so I can screw it in a tank of water and do some experimentation with several projects I have in mind.....one is passive solar water heating for a small greenhouse.....one a wood fired water heater ( I have a COOL stainless steel tank that was made for gas fired WH, )...another is active solar water heating of that same greenhouse if the passive doesn't do the trick.

NOT interested in anything electronic or battery operated....just a simple dial type face, range of 50-200 degrees F, or thereabouts. Pipe thread size not too critical, can bush it up or down as needed.....1/2" or 3/4" would be ideal.

I KNOW I've seen them, I KNOW they are made.... but a search of Google and WW Grainger neither return what I want......so you know of one, please post.

Thanks !


andy