Water temp inconsistent

I have a hamilton 780. The temp of water in our spa is inconsistent and we are experiencing very cold below freezing temps. I have tarped and setup external heat in an attempt to keep the spa from freezing.

Yesterday evening I went out to test the water temp of the spa. I found that the water level was low. I topped up the water to go over the filer barrier. The – – – symbol was on. I shut off the breaker and then put it on again. All the jets went on. I tested the water temp with a water thermometer because built in temp gauge has not been working properly for about four months. Temp was 85F. After two hours the water was lukewarm. The O N symbol was showing. I covered tub with tarps to maintain heat yesterday evening. This morning I checked under the tarp and air temp was 3 C. Checked again at lunch and water was lukewarm and the symbol was – – – After work water was hot and symbol was – – – I have now enclosed hot tub area with tarps so I can work with problem.

What do you advise?


  1. Reply

    Ivan the — symbol (WATCHDOG) can be caused by a number of things. A bad temp sensor or hi limit sensor, a bad control panel and in some cases a bad PWA. WATCHDOG can also show up if the spa is overheating. Typically when the WATCHDOG symbol shows up it in turn shuts down circulation of the spa. Because of the deep freeze outdoor temperatures we are experiencing I would recommend winterizing the spa til warmer weather arrives and then deal with the service of the spa at that time. If all else fails contact our Service Support Desk to book a diagnostic or winterize of your Sundance Spa.

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