Tub won't heat above 94 degrees

[Rutherford]

I have a 2004 Tiger River bengal spa. A few weeks back I noticed the temperature in the tub had cooled down. At first I thought the circ. pump was out as I could not detect much flow from the outlet in the bottom of the tub. I pulled the panel off and the pump was running. I attached a piece of tubing to the ozonator connection on the discharge side of the pump and raised the tubing above the water level. I powered the tub up and had flow coming out of the tube. I also put a piece of plastic over the outlet in the tub and noticed I had flow there since the plastic would not stay over it. I put everything back as it was and pushed the reset on the heater just for the hell of it. The tub heated back up to 102 degrees and all was good. A week passed and I went on a 3 day trip. When I came back the water felt cool so I put a thermometer in it and it read 94 degrees with the tub set at 102 degrees. It has maintained 94 degrees now for two days but will not heat further. The only work I have done on the tub was I replaced a burnt heater board two years back. I live too far in the boonies for repair service at a resonable cost. Any ideas on whats going on? Thanks for the help.

[MaryH]

If the heater is being supplied proper voltage while it is in a heat call then it may be the temperature sensor. Does your spa have a heat indicator that comes on when the heater should be on? If so, does that indicator come on when the water goes a couple degrees below 94degrees and goes off once it reaches 94 degrees? If so then I would think it would be that temperature sensor causing it.

[Rutherford]

Had the sensors replaced and still same problem. The tech told me that if this does not work the heater is bad. Sound right? Don't mind having it done as long as that is the problem. Just would hate to put out the money for the heater/labor and still have the problem.

[skipf]

Had the sensors replaced and still same problem. The tech told me that if this does not work the heater is bad. Sound right? Don't mind having it done as long as that is the problem. Just would hate to put out the money for the heater/labor and still have the problem.

I'm not recommending this, but had the same experience some time ago. We're also quite a ways out of town, where bailing twine and duct tape are essentials. Since the temp sensor (thirmistor) is essentially a variable resistor, I tried cutting 1 of the wires close to where it plugs in to the board, and inserting a variable resistor. then gradually changing it's setting till the heater went off and on at about the right temperature. worked like a champ. I've since replaced my heat sensor, and no longer need the extra variable resistor.