smaring

I picked up a used Hot Springs Prodigy spa recently. It has an old Watkins No Fault tri-bend "trumpet style" water heater in it that doesn't work. I'm trying to understand the operation and specifications of this heater because I'm thinking of replacing it with an adjacent in-line propane water heater with similar flow rate specs. It would make the operation of it significantly cheaper for me. I can probably figure out the flow rate by checking the specs on the water heater pump. The suggested replacement would seem to be either http://hotspringsupply.com/index.php/titanium-pdr-no-fault-heater.html or this http://hotspringsupply.com/index.php/4kw-pdr-no-fault-heater-no-pressure-switch.html