my spa will only heat if the pumps are on high. i have replaced the filter with new ones. what else could be wrong?

year make model any other info?

Control make model
pumps 1,2,... any circ pump?

kinda useless without knowing what you have.

i do not know what type or model. it is an older type with 2 pumps. the buttons to turn the pumps on are on the top (which they do not make anymore), they are white and about the size of aa half dollar. the only thing that has any writting is the control box. it has CRL 5000 on it. the pumps can be worked on at an electric supply store. (where they work on electric motors). if you turn on the pumps the water will warm up (the highest that it has gotten was 109). but the heater will not shut off when it reaches the temp that we have it set on, if the pumps are on. it just keeps on heating. but when the pumps are off, the heater will kick on. but the water will not heat up also. in order for the heater not to run all of the time, i will go and turn the pumps on for a few hours and then turn them off. this will work until winter, i guess. sorry that it took soo long, but health troubles.