I have bought a used Spa which has a Balboa GS 501 Z in it. I have two queries. The first is that there is a valve or tap on the side of the GS 501 that I don't know what it does. It just turns and doesn't tighten nor loosen and it makes no difference to the water flow from what I see. Can anybody advise me what it may be used for? You can see it pictured below:

The next thing is that the spa doesn't seem to be heating.

On the Panel, I have it set to 32oC, The heat Light is on and my power consumption increases exponentially but it never moves off of 30oC. (which I personally think the spa is much colder than that say 22oC) also I can touch the heater behind the cover and it is cool to touch.

You can see in the screenshots what I have it set to, what it says it is and also a picture of the PCB behind the cover of the GS501.

I can touch the Silver tube and it is cool. Also the fuses aren't blown from what I can see.

Thanks in advance for the help.