Welcome to our forum.
I have no idea about foamed in spas. I do know that foam would have been a bitch to work around with the configuration. I will assume that foamed in ones have a different configuration to make repairs doable.
I bet that it would be pretty difficult to meet CEC energy efficiency requirements with an air blower
I'm not talking about the blower itself but the fact that it is cooling the water and making the heater work harder, which uses lots of energy.