Just opened today and the water temp after fill is 49. Lit the heater and it caught on the first try. I notice some water dripping from the base of the heater. Is this normal when the water is so cold?
What you are experiencing is the fact that burned natural Gas has an enormous amount of water vapor as a byproduct of the combustion. When this water vapor comes into contact with the cold surface of the heat exchanger, it condenses out and forms water droplets. This is akin to the dew point you hear so much about on the weather channel. In a pool heater running natural gas, the condensation point is around 150 deg f. Once the exhaust gas lowers to that temp it will condensate. One of the problems that can occur is the water will collect the fine soot particles from the combustion process and start to clog up the heat exchanger. In the north we have this problem with home heating boilers if they are not set up properly.
You can also bypass some of the water past the heater and thus the heater has a better chance of heating up what water does go thru the heater. When you start the heater up and you hear the sizzling of the water dripping, open the manual bypass, if you have one built into the pool plumbing of the heater, and the condensation stops. So if you have this issue and no manual bypass built intot he pool plumbing of the heater, add it and see how it then acts.