You mentioned the brand name "Auqua Hot", is that a tankless hot water system? If it is then it could be an issue with pressure balance in the shower. When we were shopping we looked at a couple different MH's that had tankless hot water systems. We were cautioned about getting used to adjusting the water in the shower and finding a sweat spot when using.
Full Time in 2017 Newmar Ventana 4369
pulling a 24' enclosed (Mini Cooper/Harley/Kayak)
(traded 2014 Thor Challenger)
US Army 70-73 Retired LEO