I think it is set around 60. When installed, the plumber went back and forth between the unit and the hot water tap furthest away until he was happy with the temperature, so it could even be higher. It does feel geat when using it though.

12 Year Warranty

Hi Jim l am a Fully Licenced Plumber and recently installed a Therman 26 at my own house and from day one have the same problem you are having. I have tried everything possible to rectify this myself and are waiting on Reece to contact me after Christmas, I am very disappointed in this unit and at the moment will not install any more until l can get it sorted. I will let you know how l go. Cheers Paul.

Probably the shower heads water saving device that's causing the problem

Did you know that instantaneous hot water systems (HWS's) require a certain amount of water to pass through per second to stay active? For example if you turn your hot water tap on really lightly you will notice it doesn't stay hot. So low water pressure is the issue causing your problem. That said, low water pressure can come from 1 of 3 things:
1) you have low water pressure to your property (the least likely in suburban Australia)
2) you have a water saving shower head that doesn't allow enough water through even on full pressure (most likely, just remove the flow restrictors in it, sometimes 2 inside)
or
3) You have installed the HWS without a controller, and therefore have to use a tap to mix hot and cold water to get the correct temperature. Thus using less pressure from the HWS and substituting some or maybe even half of the pressure with mains water. In this case you will need to have a controller installed so you can run the hot water on max with no cold water mix.

Good luck!