I could really use some help with choosing new equipment. I'll be replacing the filter, pump, and heater. About the only thing I've been able to decide is that I'm going back with a sand filter. Haven't decided which one, but feel pretty comfortable being able to make this decision. Pump and heater research, however, is giving me a serious headache.
Some info on the pool:
Fiberglass pool 18600 gallons, spa 470 gallons.
New 2" plumbing going in as part of the remodel.
I'm currently looking at heater options as they seem to be the lesser of the two evils. I will be primarily, most likely exclusively, heating the spa. Have never heated the pool, nor had any inclination to do so, and as a result I'm considering going with one of the smaller heaters designed for the lower water volume.
I'm finding that a 400 BTU heater should raise 500 gallons 30 deg in 23 min.
250 BTU raises 30 deg in 38 min
100 BTU raises 30 deg in 90 min
Is this a simple math calculation? That is to say, if you run the 100 BTU heater 4x longer, are you using the same amount of gas the 400 BTU heater would use in the 23 min? If so, it comes down to wait time vs upfront cost. If not, that could affect my decision.
I have many more questions, but I'll start with this one as this seems to be the first step in narrowing down the decision.
Thanks in advance!