i like to break a good sweat..does anyone know where there is a decent sauna?

You are obviously not in Chiang Mai just now, are you?

yeah I'm here now.. i live here…i like the kind with the real rocks that water can be poured on to create extra steam

Theres a good one at the medicine hospital, but you don't need extra steam really its a challenge as it is.

30baht it was last year.

Opposite the old cultural centre .

There are saunas available at the gym/pool at the Chiang mai orchid hotel.(4th floor) 150b for entry( pay at reception) and that gives all day access to gym/pool/saunas . There are seperate saunas for male and female. No idea what the male one is like, but the female one has always been in good order and cleanse regularly.

I'm with @masuk on this--in my house, a 10-15 year old single storey concrete block construction box--I live in a sauna at the moment. I even had to put the A/C on yesterday when I went out for my daughter's young dog--he was panting like a train, and having had an operation cannot go outside.