Gilbert

I recently purchased a new submersible heater, 150w for my 14 gallon. I'm not sure if it's enough or too much.

Some factors are:

-the tank is in a cold room
-it can get cold where i live

Can the heater handle the tank or will it overheat on a warm day?

pinkfloydpuffer

Well, heaters usually only turn on when they sense that they water is getting cold, so I think it'll be fine...

Butterfly

Set it to the temp you want and the heater should come on/go off as needed to keep it an even temperature.
Carol

COBettaCouple

That heater should be plenty and you may end up setting the temp. on the heater a few degrees lower than what you want the water to stay at.