Optimum Pool TechnologiesHeater Repair Kit Compatible Replacements for Pentair® MasterTemp & Max-E-Therm - Thermistors & Switches

I have a Pentair HD250 natural gas heater. Bought and DIY installed by me. Except for the gas connection which was done by a professional. I had to replace the touchpad twice in the last 4 years. Although inexpensive, rather disappointing. So on to my latest problem. The heater would fire but after a few minutes would shut off and the red “service heater” light would come on. I could reset the system with the keypad but it would do the same thing over again. So I did some research and it looked to me like it could be one of the sensors in this package. Actually I thought it most likely to be the flue sensor. But since this package covered all the safety sensors and the thermistor I decided to spend the $100 and just replace them all as preventive maintenance as well. I did the flue sensor first and sure enough that alone fixed my issue. It took all of 5 minutes to replace it. I then went ahead and did the other 4 one at a time testing after each one. This took about 30-45 minutes only because I tested after each one. The heater now works like new. I am so satisfied with this package. By the way the water pressure sensor is better than the original it replaced (also same manufacturer) as it is a sealed unit where the original was a plunger style than engages an external micro switch. Also my thermistor was working fine but when I replaced it, it was showing some corrosion.

Great price fast delivery and everything worked perfectly and great installation video

Replaced the parts and heater came right on.

Heater Service light was coming on and heat was shutting down. Replaced the HLS (High Limit Switch) from this kit and no issues since. Now I have spare parts for any future issues too.

Had all the sensors for my pentair master temp 400 an, worked great the water pressure sensor looked different then the oem so i didn’t use it, everything worked great though.

Flue sensor will not last long, 1 year and it already needs replacing again. Yet fraction of price, OEM price is ridiculous I can buy 5 of these kits for the price of one OEM. East decision.

Bought a complete set of sensors for my pool heater came in a couple of days and I'm back in the pool. Great.

Everything was correct and installed easily.