Santon Unvented Direct PP120E - Help Please

[Bridog]

Hi everyone,

I have a Santon Premier Plus PP120E (unvented direct immersion heater) fitted with two thermostats, which provides hot water to taps and shower. The central heating runs from a separate system.

On the PP120E:

• Bottom thermostat is set it to 4 out of 5 (approx. 60C), and connected to a wall mounted timer.
• Upper thermostat is set to 3 out of 5 and connected to a wall mounted Boost button.

Through some trial & error, I have found that the Upper thermostat is always activated and heating the water, regardless of the Boost button being switched On or Off. I assume it cuts off at the set temperature (3 out of 5).

I am trying to cut down on energy costs and not have the immersion running outside of the timer function.

Questions
1. Is it safe to have the temperature gauges set to different temperatures on each thermostat?

2. If yes, and I set the Upper thermostat to 1, will it stop heating the water when I don't need it on?

3. Is there any way to use the Boost button / Upper thermostat as purely a boost function?

Hopefully that all makes sense. Any and all help is appreciated!

Thanks