Djed:
Thanks for modifying the code.I just plugged it in, and you're right.
it cycles intermittently (while it reads the other sensors, but the relay does come on now.THANK YOU.
I will try and figure out how to keep it on while one is low and the others are not.
I could have re-written it, but figured that's your job, and it will be a good learning exercise. 
It's pretty easy, so I'm sure it will come to you. 