Do not run Aqua hot with out fluid {water or antifreeze} in the water lines. If you blow out the water lines do not run the Aqua hot I did and it cost me $8,ooo for new unit. The copper lines when dry will rupture from the heat.
I had Tire Minder for years and got tired of "no signal", always one at times more. Threw it away and bought Tire Safeguard and no more 'NO SIGNALS". It rotates showing pressure and temp on all tires. no more pushing a button to see all tires. And it...