The water is too hot

Firstly, make sure you've adjusted the gas and water control knobs (red for gas, blue for water) to set your temperature. For hottest water, gas should be set to HI, and water to LO. Conversely, for coldest water, gas should be set to LO and water to HI. 

If the water temperature is getting too hot, even when you increase water flow to HI and heat to LO it usually is a poor water supply issue. The water is flowing through the HOTTAP too slowly and as a result heating up very quickly. Check the following things:

1. Incoming water temperature is too high. For example, if you have a long water inlet hose, the water in the hose can heat up in the sun – as soon as you turn on the HOTTAP the incoming water temperature is high, and the temperature shoots to 50C and will turn the unit off (safety cutoff). If this happens, try ‘flushing’ the hot water through (turn off gas so the HOTTAP doesn’t ignite a flame). After 30-60 seconds of flushing, the water in the hose should be back to normal. Turn on the gas and try again.
2. There is a blockage somewhere. This will be obvious as there won’t be any difference between the water flow out of the shower hose between the low water flow setting and high water flow setting. Usually there is a big difference between low flow and high flow. If there isn’t, it could be a blockage in the shower head, HOTTAP water inlet filter (you need to unscrew the blue quick connect adaptor), or a blockage in the pump filter.
3. If you are running off a 12V pump, check the suction side filter to make sure it is clear. If not, the pump will put out a lower flow and pressure - this will cause the water to heat up quickly. Also make sure the pump battery is fully charged. A pump running off a 50% full battery will also run at a lower flow and pressure.
4. Check the specifications on your pump (if not a Joolca pump). You should have a pump which is capable of a flow rate between 6-12LPM and a pressure setting of 40-60PSI. Anything less than 6LPM and the HOTTAP may turn off as the pump can’t supply enough water at the high water flow setting. Anything more than 12LPM and you will find your pump pulsates (goes tick tick tick tick) when you turn the water flow setting to low on the HOTTAP.