Just had a heater installed for our pool/spa. The spa runs off a separate pump, I think it is 3/4 hp. The guy who installed the heater put in 1” diameter returns and there is hardly any pressure so to speak, not enough that makes it feel like a massage. If I put in say 1/2” or 3/4” returns I know the pressure will increase but will there be any negatives as far as possible damage to the heater? There are a total of four returns in the spa.