Help! Science !!!

皮膚其實對溫度沒有多大感應，而對於熱量流入或流失有很大反應。
例如在室溫時，一本書和一件金屬同溫度，你摸金屬會比書本覺得凍得多，因為金屬把你手的熱量帶走，你覺得凍，和溫度基本沒有多大關係。熱量走得快，你會覺得溫度低。
把水調到熱天時的溫度，約30度，但只要水的溫度仍比你低，你沖涼時水不斷把熱力帶走，你會覺得很凍。
其實加上水會揮發帶走latent heat，沖涼時約39-40度才覺得不冷不熱。

I just guess i dont know right or not :

Your body tempreture should be higher than the surrounding air, so if the water's
tempreture is as the same as the surroundings, it should be lower than your body
tempreture therefore you feel cold.

Your question seems incomplete ! There should be some sentences in front describing what temperature the heater is set.

You feel the water from the heater hot or cold depends on the prevailing air temperature. In summer, the air temperature is high, so you feel the water is cool. But in winter, the air temperature is some 20 degrees Celsius lower than that in summer, you would feel the water becomes warm.