Balboa Spa Packs generate helpful error messages, but sometimes they may give us the wrong idea or cause panic when the solution is rather simple.
The other day, our Balboa powered hot tub flashed a “heater dry requires service” message. Instantly I envisoned at least another hundred dollar bill flying through the wind but then came to my senses and isolated the problem.
The heater is dry because it has an air pocket in it, which coincides with the fact that the spa was just freshly refilled after a long and cold winter. When the two sensors within the heater tube are more than 6 degrees F apart, they cause this message to appear and shut down the heater so there is no danger of fire or explosion (which can happen if a heater is left to heat air in the heater tube instead of water). The latest spa packs come complete with these safety mechanisms to avoid any problems.
Even older spas had a FLO message when the pressure switch which was usually mounted on the heater, did not detect adequate water flow. This also turned the heater off automatically during a fault condition.
So solving the problem would have meant opening the discharge union on the pumps (as well as the heater), to blead out any air until water starts coming out, then quickly tightening the union again. These heater unions should just be hand tightened and not heavily tightened with channel locks to avoid cracking the plumbing parts, but many hot tub manufactures indeed use channel locks for a tighter fit on new spas to avoid plumbing unions coming loose during transport to the customer.
In my case, I could not get the union off by hand because they were on very tight, so I had two options: buy a set of channel locks (jumbo pliers) or try to force water through the system. I opted for the lazy way and turned the pump on high speed, took the filter out to eliminate any resistance there, put a garden hose in the filter area so once it started surging, it would not suck air back into the system. I also turned the pump on low and high speed to alternate the water flow and it finally primed itself and purged the remaining air without me needing to open up the plumbing unions.
In the end, the Balboa error message said the hot tub requires service, but what it really meant was just a heavier handed startup proceedure to get the trapped air out of the heater and restore normal water pressure within the heater so the spa could then heat again.
Good luck purging air out of your system to get the spa working again without the need for a service call.