We have a standalone spa with this 200,000 BTU gas heater. To me, this is superior to the typical electric heated self-contained systems because it heats cold tap water to 104 degrees in about 30 minutes in our 250 gallon spa. In CA, gas is cheap compared to electricity for heating. With an insulating cover, we get in and run the heater for only 6 minutes to get from 94 to 100 degrees. That way, it's not scalding hot when you get in, but cranks up fast.

The Hayward H-Series H250FDN is extremely reliable and energy efficient. It marries high performance with environmentally responsible low NOx emissions and can provide energy savings of up to 18% compared to other similar pool heaters.

Purchased in Sept. 2016, had to replace the heat exchanger once, but we were not sure if it was too much water flow, or chemical imbalance. But, this unit heats my 33,000 gallon (DE filter system) very quickly, and reliably. The regional rep (Greg) was very easy to deal with and made the experience more understandable as far as issues and made replacing the heat exchanger a fair and straightforward one. Just a word of caution - overly high water flow into the heater can and likely will cause the coils to deteriorate, and this can happen in less than a year. So, be sure your pool pump is sending a reasonable flow through the system (you can call Hayward for details) as well as balancing your chems. The replacement heat exchange assembly costs about $1,100 (plus $200-400 for labor), so replacing can approach the cost of an entirely new heater.

Finally replaced our hold Hayward heater after 15 years (it actually exploded, otherwise, we'd probably still be using it). This is a great replacement, seems to heat a little faster than the old one. A little smaller. The only thing I wish that Hayward had done was not to change the layout of the connections. Had to replumb and redo gas line.

Bought this to replace an old broken rusted out Hayward H400IDL that was about 15 years old. My old heater seemed to breakdown every 3 months or so. I’m hoping this one will be more reliable. The installation wasn’t to bad I did it myself but the biggest negative was when I called Hayward and they told me the H400FDN was an exact replacement that wouldn’t need plumbing adjustments to fit but that wasn’t the case both the water and gas connections had to be reworked to line up. Nothing to difficult but it required a trip to Lowe’s to get everything working. Overall it seems like a good heater although it doesn’t look like the picture shown on amazon? the control panel is completely different then what is shown. Also don’t forget to register online for your warranty and apply for a rebate with your local gas company I got an extra $300 off with a rebate from SoCalGas.